Transition metal ion incorporation has been emerged as an effective stratagem to enhance the perf... more Transition metal ion incorporation has been emerged as an effective stratagem to enhance the performance of metal oxide photoanodes. In the present work, we design and fabricate the plain ZnO and (2, 5, 10 and 15%) Fe incorporated ZnO photoanode by aerosol assisted chemical vapor deposition (AACVD) method. The 15% Fe incorporated ZnO photoanode displayed excellent photocurrent density of 4.6 mA/cm 2 at 0.7 VAg/AgCl with photo conversion efficiency of 2.4%, which is 159 times higher than pure ZnO photoanode (0.028 mA/cm 2). The obtained results are remarkably superior to the previous results. Furthermore, the Fe incorporated photoelectrodes have also shown good stability. The excellent photoelectrochemical performance of Fe incorporated ZnO showed red shift in band edge with relative decrease in the band gap energy compared to pure ZnO. The demonstration of this simple method for the deposition of Fe incorporated ZnO to fabricate highly efficient photoanode for the PEC water splitting can easily be applied to other similar systems.
The synergic effect of Ni and Ag in Ni–Ag–ZnO solid solutions has tuned the optoelectronic proper... more The synergic effect of Ni and Ag in Ni–Ag–ZnO solid solutions has tuned the optoelectronic properties of ZnO for photoreduction reactions.
Herein, we report the synthesis of Zn 2 SnO 4 (ZTO) nanoparticles via sol-gel method at room temp... more Herein, we report the synthesis of Zn 2 SnO 4 (ZTO) nanoparticles via sol-gel method at room temperature. The as-synthesized ZTO nanoparticles were characterized by using fourier transform infra-red spectroscopy (FT-IR), powdered X-ray diffraction (pXRD), UV-visible spectroscopy, and field emission scanning electron microscopy (FE-SEM). Photocatalytic activity of as-prepared zinc stannate (ZTO) was tested by fabricating ZTO thin films on glass substrates. The photocatalytic degradation of methyl orange (MO) and methylene blue (MB) was estimated by using ZTO nanoparticle thin films under UV light irradiation for 1 h. Photo catalytic degradation of MO and MB by the ZTO nanocrystals showed that the ZTO acted as a potential photocatalyst under unfiltered natural sunlight of irradiation 300 W/m 2. The MO dye was degraded about 73% and MB was degraded about 62% in the presence of ZTO nanoparticles respectively in 60 min.
Resolution of resources and environmental crises requires an efficient separation technologies, c... more Resolution of resources and environmental crises requires an efficient separation technologies, consequently, scientists and engineers are working vigorously for ideal separation materials. Laminar graphene oxide (GO) is a two-dimensional (2D) material offers considerable interest in this field due to its single atomic layer thickness, good stability, chemical inertness, and variety of functional groups. Recently, GO have emerged as a novel membrane material for molecular and ionic separation of gases, solvent, water, and desalination applications. This tutorial review aims to discuss the various approaches used to control the stacking of GO-based membrane with emphasis of advantages and drawbacks associated with each approach. Further, attention will also be given to describe the recent progress in GO based membranes for ionic and molecular separations. Meanwhile, challenges and opportunities will also be discussed in detail. We hope this review expected to provide a compact source of information that will be of great interest to chemists, material scientists, physicists, and engineers working or planning to work in GO based membranes for separation applications.
Herein, we report the synthesis of RGO-β-Bi 2 O 3 nanocomposite for visible light driven efficien... more Herein, we report the synthesis of RGO-β-Bi 2 O 3 nanocomposite for visible light driven efficient photocatalytic removal of wastewater pollutant. Improved oxidation of pristine graphite (PG) to graphene oxide (GO) was obtained by involving additional oxiding agent Na 2 S 2 O 8 in Hummer's method. The as-synthesized reduced graphene oxide (RGO) was decorated with β-bismuth oxide to develop RGO-β-Bi 2 O 3 nanocomposite via in-situ wet processing method. The as-prepared na-nocomposites were characterized by range of techniques. The photocatalytic activity of as-prepared RGO-β-Bi 2 O 3 nanocomposite was investigated for the degradation of commercially available dye Direct Yellow-27 (DY-27), which is extensively used in the textile industries. The as-syntesized RGO-β-Bi 2 O 3 nanocomposite's photocatalysis shows first order kinetic. Furthermore, effect of dye concentration, pH, catalyst loading and temperature were studied to optimize the photocatalytic performance. The enhanced photocatalytic efficiency of nanocomposite could be attributed to the greater surface area and reduction in recombination of excited electron and holes.
In this work, we present an effective and facile approach for deposition of zinc oxide, and nicke... more In this work, we present an effective and facile approach for deposition of zinc oxide, and nickel incorporated zinc oxide thin films to fabricate photoanode of photoelectrochemical cell. Incorporation of Ni 2+ in the host ZnO matrix results in the dramatic shape evolution of the resulting films from simple bullet like structures to complex punch like microstructures with increased estimated electrochemically active surface area. In addition to the role of Ni 2+ in structure determination, it significantly enhanced the photoelectrochemical performance by improving the charge transport properties and conductivity of the parent host matrix. This work demonstrates a move towards tailoring functional properties of the films via controlled incorporation of different ionic species. This simple incorporation scheme can further be applied to attain a variety of compositionally tunable unique structures for desired applications by judiciously adjusting precursor choices and manipulating relative concentrations of the incorporated precursors during growth.
The development of low-cost, durable and efficient photocatalyst for overall photoelectrochemical... more The development of low-cost, durable and efficient photocatalyst for overall photoelectrochemical water splitting is in demand to overcome the renewable energy crises. Herein, we demonstrate the efficient photoelec-trochemical water splitting by cobalt (Co) incorporated zinc oxide (Zn 1-x Co x O) thin films deposited via aerosol assisted chemical vapour deposition (AACVD) technique. The as-deposited Co incorporated ZnO thin films were characterised by powdered X-ray diffraction (pXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high resolution transmission electron mi-croscopy (HRTEM) and ultra violet-visible spectroscopy (UV-Vis). These films with different concentration of cobalt were investigated for water splitting applications and the best results were achieved for the films with 15% Co incorporation.
Nanomaterials synthesis using single source precursors is a fascinating development in material s... more Nanomaterials synthesis using single source precursors is a fascinating development in material science. The shape and size dependent properties offer countless opportunities for interesting discoveries, but also poses challenges to the scientific community to control the shape and size of these materials. Selenocarboxylate complexes are difficult to synthesize, due to the instability of selenocarboxylic acids. In this study, we have developed an efficient one-pot synthesis of the selenobenzoate ligand and its three new metal complexes, tris(selenobenzoato)antimony(III), tris(selenobenzoato)bismuth(III) and bis(selenobenzoato)dibutyltin(IV). The complexes were used as single source precursors to synthesize Sb 2 Se 3 nanorods, Bi 2 Se 3 and SnSe nanosheets by colloidal thermolysis using the hot injection method. The as-synthesized nanomaterials were characterized by p-XRD, TEM, SAED and HRTEM techniques. The complexes were synthesized by a facile method with high yields and are stable at room temperature for period of several months, We believe that the selenobenzoate complexes with other metals can also be synthesized by using our method and those complexes can be useful precursors for metal selenide thin films or nanoparticles.
Un-doped zinc sulphide (ZnS) and noble metal-doped ZnS quantum dots were synthesized by chemical ... more Un-doped zinc sulphide (ZnS) and noble metal-doped ZnS quantum dots were synthesized by chemical method. The synthesized nanomaterial was characterized by UV-Visible, Fourier Transformed Infra-red Spectrometer (FTIR), Fluorescence, High Resolution Transmission Electron Microscope (HRTEM) and X-ray Diffraction (XRD). Scanning electron microscope complemented with energy dispersive X-ray was used to study particle size and chemical composition of un-doped and metal-doped ZnS QDs. A significant red shift in absorption band was observed in metal doped ZnS sample having concentration of impurity 0.05 M with respect to the un-doped ZnS with increasing the size of nanocrystals. Such red shift of the absorption bands are attributed due to quantum confinement effect. As un-doped and noble metal-doped ZnS QDs are direct band gap materials. The band gap energy of ZnS, Ag-doped, and Au-doped ZnS quantum dots is found to 2.5 eV, 2.4 eV and 2.2 eV, respectively. PL spectrum of the un-doped zinc sul-phide nanocrytals witnessed two bands, first at 418 nm and second at 468 nm. However, PL spectrum of Ag-doped ZnS nanocrystals shows no green light emission band while a broad emission ranging up to 700 nm in Au-doped ZnS sample. XRD spectra of synthesized QDs exhibited that the material was in cubic phase. X-ray Photoelectron Spectroscopy (XPS) was used for comparative study of surfaces of zinc sulphide and noble metal zinc sulphide nanocrystals. The effects of inserting ZnS and noble metal doped ZnS nanocrystals in the active layer on the performance of organic solar cells were studied. The active layer mainly comprises of electron acceptor [6,6] phenyl-C61-butyric acid methyl ester (PCBM) and organic electron donor poly (3-hexylthiophene (P3HT) with quantum dots dissolved in dichlorobenzene. The cell conversion efficiency improved by embedding the doped QDs in the active layer blend. The cells fabricated with ZnS QDs exhibited cell conversion efficiency of 1.46%. By doping with silver and gold, the cell conversion efficiency was increased about 1.85% and 2.01%, respectively. The morphology of blend of nanocrystals with P3HT:PCBM were studied using atomic force microscopy.
Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenabilit... more Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenability and improved optical properties compared to their single metal halide perovskites. It is thus valuable to investigate compositional changes in lead halide perovskites to explore energy changes. Herein, we report the synthesis of a lead to lead free hybrid perovskite solid solution (CH 3 NH 3 Pb 1Àx Cu x Br 3) as nanoparticles and films. The increasing concentration of Cu 2+ ions in the site of the Pb 2+ ion in the perovskite shifted the diffraction peaks to a larger angle. Uniform spherically shaped nanoparticles were synthesized by a wet chemical method, the higher Cu 2+ concentration leads to agglomeration, producing sheet like morphologies. However, the deposition of thin films of CH 3 NH 3 Pb 1Àx Cu x Br 3 perovskite solid solution shows that well defined morphologies begin to appear with increasing concentrations of Cu 2+ in the perovskite structure. The as-prepared bulk lead free CH 3 NH 3 CuBr 3 perovskite shows a band gap of 1.65 eV. A blue shift in photoluminescence (PL) was observed with copper enriched hybrid perovskites.
In this study a facile and potentially scalable synthesis of AgBiS2 (schapbachite) is presented b... more In this study a facile and potentially scalable synthesis of AgBiS2 (schapbachite) is presented by a melt of metal xanthates, it is both a significant mineral and a technological material. The ternary material was synthesized by a novel and low-cost solventless route using simple ethyl xanthate complexes of silver and bismuth. p-XRD analysis indicates that the synthesized ternary material is highly crystalline belonging to the cubic phase (Schapbachite). The electrochemical properties of the material were tested, the potential of the synthesized material for charge storage application shows a high specific capacitance of 460 F/g at 2 mV/s. A capacitance retention of 83 % with 100 % coulombic efficiency was observed after 3000 cycles. The charge storage potential, by fabricating actual symmetrical device, shows a specific capacitance of 14 F/g at 2mV/s. An energy density of 26 Wh/Kg and power density of 3.6 KW/Kg was observed. Besides, the potential for oxygen evolution reaction was also studied. An overpotential of 414 mV and Tafel slope of 134 mV/dec was obtained for water oxidation. The fabrication of electrolyzer cell, using synthesized material as cathode, indicates that a current of 10 mA/cm2 can be achieved at a potential of 1.63 V.
This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I pe... more This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I perovskite thin films using aerosol assisted chemical vapour deposition (AACVD) at 100 °C. Room temperature optical measurements performed on as-deposited thin films shown two absorption peaks. Upon 325 nm excitation, CsZnCl2I perovskite thin film showed broad band white light emission having two peaks, which cover the entire visible range of the spectrum. This is the first example of white light emission from 3D all-inorganic lead free mixed halide CsZnCl2I perovskites.
PAPER Javeed Akhtar, Jean-Michel Nunzi et al. Fabrication of planar heterojunction CsPbBr 2 I per... more PAPER Javeed Akhtar, Jean-Michel Nunzi et al. Fabrication of planar heterojunction CsPbBr 2 I perovskite solar cells using ZnO as an electron transport layer and improved solar energy conversion efficiency Inorganic lead halide perovskite solar cells with mixed halides have achieved reasonable power conversion efficiency with the advantage of enhanced stability. In this work, we report the fabrication of an allinorganic cesium lead bromoiodide based planar perovskite solar cell with a ZnO electron transport layer.
Metal halide perovskites have emerged as a potential candidate for photovoltaic and light emittin... more Metal halide perovskites have emerged as a potential candidate for photovoltaic and light emitting applications. Tuning the optical properties by tailoring the perovskite nanostructures could enhance the efficiency of these devices. Herein, we report the synthesis of hybrid to inorganic quasi-2D perov-skites, by using different ratios of PhNH 3 Br and CsI, to prepare (Cs) x (PhNH 3) 2-2x PbBr 4-x I x nanomaterials. The as-prepared nano-structures were characterized by powder X-ray diffraction (p-XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible spectroscopy (UV/Vis). Transmission electron mi-croscopy (TEM) showed that the shape of the as-prepared nanostructures can be tuned from rectangle/rods to sheet like structures. It was observed that the ratio of the organic cation (anilinium ion) plays a crucial role in the development of the perovskite crystallites size and shape. This is the first such study on the conversion of hybrid 2D perovskite to inorganic quasi-2D perovskite by using inorganic cation (Cs +) and could be a potential material for optoelectronic applications.
We report a facile approach to prepare nanostructures of all-inorganic perovskite CsPbBr 2 I by t... more We report a facile approach to prepare nanostructures of all-inorganic perovskite CsPbBr 2 I by the wet chemical and aerosol assisted chemical vapour deposition (AACVD) methods using oleylamine (OLA) as a shape modifier. This study explores the role of OLA during the formation of nanosquares via both methods.
A new organo-tin complex has been synthesized and used as a single source precursor for the synth... more A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the depo-sition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectro-chemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential.
A new organo-tin complex has been synthesized and used as a single source precursor for the synth... more A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth was found to be significantly altered by the changes in deposition temperature. Oleylamine capped nanosheets and as deposited thin films by AACVD, were characterized by powder X-Ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), by switching the applied potential.
Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent ... more Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX 3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.
To achieve a material with pure phase and crystalli-nity, the use of antisolvents is found to be ... more To achieve a material with pure phase and crystalli-nity, the use of antisolvents is found to be crucial. Herein, we report the synthesis of phase-pure CsPbBr 2 I microcrystals with defined morphologies by using trioctylphosphine (TOP) as an antisolvent and capping agent. The as-prepared inorganic
Transition metal ion incorporation has been emerged as an effective stratagem to enhance the perf... more Transition metal ion incorporation has been emerged as an effective stratagem to enhance the performance of metal oxide photoanodes. In the present work, we design and fabricate the plain ZnO and (2, 5, 10 and 15%) Fe incorporated ZnO photoanode by aerosol assisted chemical vapor deposition (AACVD) method. The 15% Fe incorporated ZnO photoanode displayed excellent photocurrent density of 4.6 mA/cm 2 at 0.7 VAg/AgCl with photo conversion efficiency of 2.4%, which is 159 times higher than pure ZnO photoanode (0.028 mA/cm 2). The obtained results are remarkably superior to the previous results. Furthermore, the Fe incorporated photoelectrodes have also shown good stability. The excellent photoelectrochemical performance of Fe incorporated ZnO showed red shift in band edge with relative decrease in the band gap energy compared to pure ZnO. The demonstration of this simple method for the deposition of Fe incorporated ZnO to fabricate highly efficient photoanode for the PEC water splitting can easily be applied to other similar systems.
The synergic effect of Ni and Ag in Ni–Ag–ZnO solid solutions has tuned the optoelectronic proper... more The synergic effect of Ni and Ag in Ni–Ag–ZnO solid solutions has tuned the optoelectronic properties of ZnO for photoreduction reactions.
Herein, we report the synthesis of Zn 2 SnO 4 (ZTO) nanoparticles via sol-gel method at room temp... more Herein, we report the synthesis of Zn 2 SnO 4 (ZTO) nanoparticles via sol-gel method at room temperature. The as-synthesized ZTO nanoparticles were characterized by using fourier transform infra-red spectroscopy (FT-IR), powdered X-ray diffraction (pXRD), UV-visible spectroscopy, and field emission scanning electron microscopy (FE-SEM). Photocatalytic activity of as-prepared zinc stannate (ZTO) was tested by fabricating ZTO thin films on glass substrates. The photocatalytic degradation of methyl orange (MO) and methylene blue (MB) was estimated by using ZTO nanoparticle thin films under UV light irradiation for 1 h. Photo catalytic degradation of MO and MB by the ZTO nanocrystals showed that the ZTO acted as a potential photocatalyst under unfiltered natural sunlight of irradiation 300 W/m 2. The MO dye was degraded about 73% and MB was degraded about 62% in the presence of ZTO nanoparticles respectively in 60 min.
Resolution of resources and environmental crises requires an efficient separation technologies, c... more Resolution of resources and environmental crises requires an efficient separation technologies, consequently, scientists and engineers are working vigorously for ideal separation materials. Laminar graphene oxide (GO) is a two-dimensional (2D) material offers considerable interest in this field due to its single atomic layer thickness, good stability, chemical inertness, and variety of functional groups. Recently, GO have emerged as a novel membrane material for molecular and ionic separation of gases, solvent, water, and desalination applications. This tutorial review aims to discuss the various approaches used to control the stacking of GO-based membrane with emphasis of advantages and drawbacks associated with each approach. Further, attention will also be given to describe the recent progress in GO based membranes for ionic and molecular separations. Meanwhile, challenges and opportunities will also be discussed in detail. We hope this review expected to provide a compact source of information that will be of great interest to chemists, material scientists, physicists, and engineers working or planning to work in GO based membranes for separation applications.
Herein, we report the synthesis of RGO-β-Bi 2 O 3 nanocomposite for visible light driven efficien... more Herein, we report the synthesis of RGO-β-Bi 2 O 3 nanocomposite for visible light driven efficient photocatalytic removal of wastewater pollutant. Improved oxidation of pristine graphite (PG) to graphene oxide (GO) was obtained by involving additional oxiding agent Na 2 S 2 O 8 in Hummer's method. The as-synthesized reduced graphene oxide (RGO) was decorated with β-bismuth oxide to develop RGO-β-Bi 2 O 3 nanocomposite via in-situ wet processing method. The as-prepared na-nocomposites were characterized by range of techniques. The photocatalytic activity of as-prepared RGO-β-Bi 2 O 3 nanocomposite was investigated for the degradation of commercially available dye Direct Yellow-27 (DY-27), which is extensively used in the textile industries. The as-syntesized RGO-β-Bi 2 O 3 nanocomposite's photocatalysis shows first order kinetic. Furthermore, effect of dye concentration, pH, catalyst loading and temperature were studied to optimize the photocatalytic performance. The enhanced photocatalytic efficiency of nanocomposite could be attributed to the greater surface area and reduction in recombination of excited electron and holes.
In this work, we present an effective and facile approach for deposition of zinc oxide, and nicke... more In this work, we present an effective and facile approach for deposition of zinc oxide, and nickel incorporated zinc oxide thin films to fabricate photoanode of photoelectrochemical cell. Incorporation of Ni 2+ in the host ZnO matrix results in the dramatic shape evolution of the resulting films from simple bullet like structures to complex punch like microstructures with increased estimated electrochemically active surface area. In addition to the role of Ni 2+ in structure determination, it significantly enhanced the photoelectrochemical performance by improving the charge transport properties and conductivity of the parent host matrix. This work demonstrates a move towards tailoring functional properties of the films via controlled incorporation of different ionic species. This simple incorporation scheme can further be applied to attain a variety of compositionally tunable unique structures for desired applications by judiciously adjusting precursor choices and manipulating relative concentrations of the incorporated precursors during growth.
The development of low-cost, durable and efficient photocatalyst for overall photoelectrochemical... more The development of low-cost, durable and efficient photocatalyst for overall photoelectrochemical water splitting is in demand to overcome the renewable energy crises. Herein, we demonstrate the efficient photoelec-trochemical water splitting by cobalt (Co) incorporated zinc oxide (Zn 1-x Co x O) thin films deposited via aerosol assisted chemical vapour deposition (AACVD) technique. The as-deposited Co incorporated ZnO thin films were characterised by powdered X-ray diffraction (pXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high resolution transmission electron mi-croscopy (HRTEM) and ultra violet-visible spectroscopy (UV-Vis). These films with different concentration of cobalt were investigated for water splitting applications and the best results were achieved for the films with 15% Co incorporation.
Nanomaterials synthesis using single source precursors is a fascinating development in material s... more Nanomaterials synthesis using single source precursors is a fascinating development in material science. The shape and size dependent properties offer countless opportunities for interesting discoveries, but also poses challenges to the scientific community to control the shape and size of these materials. Selenocarboxylate complexes are difficult to synthesize, due to the instability of selenocarboxylic acids. In this study, we have developed an efficient one-pot synthesis of the selenobenzoate ligand and its three new metal complexes, tris(selenobenzoato)antimony(III), tris(selenobenzoato)bismuth(III) and bis(selenobenzoato)dibutyltin(IV). The complexes were used as single source precursors to synthesize Sb 2 Se 3 nanorods, Bi 2 Se 3 and SnSe nanosheets by colloidal thermolysis using the hot injection method. The as-synthesized nanomaterials were characterized by p-XRD, TEM, SAED and HRTEM techniques. The complexes were synthesized by a facile method with high yields and are stable at room temperature for period of several months, We believe that the selenobenzoate complexes with other metals can also be synthesized by using our method and those complexes can be useful precursors for metal selenide thin films or nanoparticles.
Un-doped zinc sulphide (ZnS) and noble metal-doped ZnS quantum dots were synthesized by chemical ... more Un-doped zinc sulphide (ZnS) and noble metal-doped ZnS quantum dots were synthesized by chemical method. The synthesized nanomaterial was characterized by UV-Visible, Fourier Transformed Infra-red Spectrometer (FTIR), Fluorescence, High Resolution Transmission Electron Microscope (HRTEM) and X-ray Diffraction (XRD). Scanning electron microscope complemented with energy dispersive X-ray was used to study particle size and chemical composition of un-doped and metal-doped ZnS QDs. A significant red shift in absorption band was observed in metal doped ZnS sample having concentration of impurity 0.05 M with respect to the un-doped ZnS with increasing the size of nanocrystals. Such red shift of the absorption bands are attributed due to quantum confinement effect. As un-doped and noble metal-doped ZnS QDs are direct band gap materials. The band gap energy of ZnS, Ag-doped, and Au-doped ZnS quantum dots is found to 2.5 eV, 2.4 eV and 2.2 eV, respectively. PL spectrum of the un-doped zinc sul-phide nanocrytals witnessed two bands, first at 418 nm and second at 468 nm. However, PL spectrum of Ag-doped ZnS nanocrystals shows no green light emission band while a broad emission ranging up to 700 nm in Au-doped ZnS sample. XRD spectra of synthesized QDs exhibited that the material was in cubic phase. X-ray Photoelectron Spectroscopy (XPS) was used for comparative study of surfaces of zinc sulphide and noble metal zinc sulphide nanocrystals. The effects of inserting ZnS and noble metal doped ZnS nanocrystals in the active layer on the performance of organic solar cells were studied. The active layer mainly comprises of electron acceptor [6,6] phenyl-C61-butyric acid methyl ester (PCBM) and organic electron donor poly (3-hexylthiophene (P3HT) with quantum dots dissolved in dichlorobenzene. The cell conversion efficiency improved by embedding the doped QDs in the active layer blend. The cells fabricated with ZnS QDs exhibited cell conversion efficiency of 1.46%. By doping with silver and gold, the cell conversion efficiency was increased about 1.85% and 2.01%, respectively. The morphology of blend of nanocrystals with P3HT:PCBM were studied using atomic force microscopy.
Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenabilit... more Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenability and improved optical properties compared to their single metal halide perovskites. It is thus valuable to investigate compositional changes in lead halide perovskites to explore energy changes. Herein, we report the synthesis of a lead to lead free hybrid perovskite solid solution (CH 3 NH 3 Pb 1Àx Cu x Br 3) as nanoparticles and films. The increasing concentration of Cu 2+ ions in the site of the Pb 2+ ion in the perovskite shifted the diffraction peaks to a larger angle. Uniform spherically shaped nanoparticles were synthesized by a wet chemical method, the higher Cu 2+ concentration leads to agglomeration, producing sheet like morphologies. However, the deposition of thin films of CH 3 NH 3 Pb 1Àx Cu x Br 3 perovskite solid solution shows that well defined morphologies begin to appear with increasing concentrations of Cu 2+ in the perovskite structure. The as-prepared bulk lead free CH 3 NH 3 CuBr 3 perovskite shows a band gap of 1.65 eV. A blue shift in photoluminescence (PL) was observed with copper enriched hybrid perovskites.
In this study a facile and potentially scalable synthesis of AgBiS2 (schapbachite) is presented b... more In this study a facile and potentially scalable synthesis of AgBiS2 (schapbachite) is presented by a melt of metal xanthates, it is both a significant mineral and a technological material. The ternary material was synthesized by a novel and low-cost solventless route using simple ethyl xanthate complexes of silver and bismuth. p-XRD analysis indicates that the synthesized ternary material is highly crystalline belonging to the cubic phase (Schapbachite). The electrochemical properties of the material were tested, the potential of the synthesized material for charge storage application shows a high specific capacitance of 460 F/g at 2 mV/s. A capacitance retention of 83 % with 100 % coulombic efficiency was observed after 3000 cycles. The charge storage potential, by fabricating actual symmetrical device, shows a specific capacitance of 14 F/g at 2mV/s. An energy density of 26 Wh/Kg and power density of 3.6 KW/Kg was observed. Besides, the potential for oxygen evolution reaction was also studied. An overpotential of 414 mV and Tafel slope of 134 mV/dec was obtained for water oxidation. The fabrication of electrolyzer cell, using synthesized material as cathode, indicates that a current of 10 mA/cm2 can be achieved at a potential of 1.63 V.
This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I pe... more This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I perovskite thin films using aerosol assisted chemical vapour deposition (AACVD) at 100 °C. Room temperature optical measurements performed on as-deposited thin films shown two absorption peaks. Upon 325 nm excitation, CsZnCl2I perovskite thin film showed broad band white light emission having two peaks, which cover the entire visible range of the spectrum. This is the first example of white light emission from 3D all-inorganic lead free mixed halide CsZnCl2I perovskites.
PAPER Javeed Akhtar, Jean-Michel Nunzi et al. Fabrication of planar heterojunction CsPbBr 2 I per... more PAPER Javeed Akhtar, Jean-Michel Nunzi et al. Fabrication of planar heterojunction CsPbBr 2 I perovskite solar cells using ZnO as an electron transport layer and improved solar energy conversion efficiency Inorganic lead halide perovskite solar cells with mixed halides have achieved reasonable power conversion efficiency with the advantage of enhanced stability. In this work, we report the fabrication of an allinorganic cesium lead bromoiodide based planar perovskite solar cell with a ZnO electron transport layer.
Metal halide perovskites have emerged as a potential candidate for photovoltaic and light emittin... more Metal halide perovskites have emerged as a potential candidate for photovoltaic and light emitting applications. Tuning the optical properties by tailoring the perovskite nanostructures could enhance the efficiency of these devices. Herein, we report the synthesis of hybrid to inorganic quasi-2D perov-skites, by using different ratios of PhNH 3 Br and CsI, to prepare (Cs) x (PhNH 3) 2-2x PbBr 4-x I x nanomaterials. The as-prepared nano-structures were characterized by powder X-ray diffraction (p-XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible spectroscopy (UV/Vis). Transmission electron mi-croscopy (TEM) showed that the shape of the as-prepared nanostructures can be tuned from rectangle/rods to sheet like structures. It was observed that the ratio of the organic cation (anilinium ion) plays a crucial role in the development of the perovskite crystallites size and shape. This is the first such study on the conversion of hybrid 2D perovskite to inorganic quasi-2D perovskite by using inorganic cation (Cs +) and could be a potential material for optoelectronic applications.
We report a facile approach to prepare nanostructures of all-inorganic perovskite CsPbBr 2 I by t... more We report a facile approach to prepare nanostructures of all-inorganic perovskite CsPbBr 2 I by the wet chemical and aerosol assisted chemical vapour deposition (AACVD) methods using oleylamine (OLA) as a shape modifier. This study explores the role of OLA during the formation of nanosquares via both methods.
A new organo-tin complex has been synthesized and used as a single source precursor for the synth... more A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the depo-sition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectro-chemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential.
A new organo-tin complex has been synthesized and used as a single source precursor for the synth... more A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth was found to be significantly altered by the changes in deposition temperature. Oleylamine capped nanosheets and as deposited thin films by AACVD, were characterized by powder X-Ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), by switching the applied potential.
Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent ... more Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX 3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.
To achieve a material with pure phase and crystalli-nity, the use of antisolvents is found to be ... more To achieve a material with pure phase and crystalli-nity, the use of antisolvents is found to be crucial. Herein, we report the synthesis of phase-pure CsPbBr 2 I microcrystals with defined morphologies by using trioctylphosphine (TOP) as an antisolvent and capping agent. The as-prepared inorganic
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Papers by Muhammad Aamir
is both a significant mineral and a technological material. The ternary material was synthesized by a novel and low-cost
solventless route using simple ethyl xanthate complexes of silver and bismuth. p-XRD analysis indicates that the synthesized
ternary material is highly crystalline belonging to the cubic phase (Schapbachite). The electrochemical properties of the
material were tested, the potential of the synthesized material for charge storage application shows a high specific
capacitance of 460 F/g at 2 mV/s. A capacitance retention of 83 % with 100 % coulombic efficiency was observed after 3000
cycles. The charge storage potential, by fabricating actual symmetrical device, shows a specific capacitance of 14 F/g at
2mV/s. An energy density of 26 Wh/Kg and power density of 3.6 KW/Kg was observed. Besides, the potential for oxygen
evolution reaction was also studied. An overpotential of 414 mV and Tafel slope of 134 mV/dec was obtained for water
oxidation. The fabrication of electrolyzer cell, using synthesized material as cathode, indicates that a current of 10 mA/cm2
can be achieved at a potential of 1.63 V.
is both a significant mineral and a technological material. The ternary material was synthesized by a novel and low-cost
solventless route using simple ethyl xanthate complexes of silver and bismuth. p-XRD analysis indicates that the synthesized
ternary material is highly crystalline belonging to the cubic phase (Schapbachite). The electrochemical properties of the
material were tested, the potential of the synthesized material for charge storage application shows a high specific
capacitance of 460 F/g at 2 mV/s. A capacitance retention of 83 % with 100 % coulombic efficiency was observed after 3000
cycles. The charge storage potential, by fabricating actual symmetrical device, shows a specific capacitance of 14 F/g at
2mV/s. An energy density of 26 Wh/Kg and power density of 3.6 KW/Kg was observed. Besides, the potential for oxygen
evolution reaction was also studied. An overpotential of 414 mV and Tafel slope of 134 mV/dec was obtained for water
oxidation. The fabrication of electrolyzer cell, using synthesized material as cathode, indicates that a current of 10 mA/cm2
can be achieved at a potential of 1.63 V.