Surbhi Choudhary

PHOTOELECTROCHEMICAL WATER SPLITTING USING BILAYERED ZnO/SrTiO3 PHOTOELECTRODES

Nanostructured zinc oxide overlayered by nanoporous strontium titanate was synthesized using sol-gel method and tested in a photoelectrochemical (PEC) cell for splitting of water. It was found that compared to the pristine ZnO and SrTiO3, the resistivity of bilayered thin film was reduced and a negative shift in open circuit potential and flatband potential of bilayered ZnO/SrTiO3 was observed, thus improving the photocurrent density and photoconversion efficiency. Significantly, bilayered ZnO/SrTiO3 thin film offered the best photocurrent density i.e. 0.46 mA/cm2 at 0 V/SCE. XRD, SEM and UV-Vis spectroscopic studies were carried out to explore the structural, surface morphological and optical properties of various thin films.

Photoelectrochemical performance of CuO electrodes by surface modification with ZnO in water splitting process

Nanostructured CuO thin film photoelectrodes of altering thickness modified by overlayering of ZnO thin films were used in photoelectrochemical (PEC) water splitting. The influence of surface modification, by layering of wide band gap semiconductor over small band gap semiconductor with appropriate thickness, on PEC performance and the stability has been investigated. It was found that modified CuO thin films showed significant enhancement in photocurrent density and photoconversion efficiency and better stability than that of pristine CuO photoelectrodes. Maximum photocurrent 2 density 1.52 mA/cm2 at -0.8 V/SCE under visible light illumination for CuO/ZnO thin films was observed offering 1.23% photoconversion efficiency. An energy band diagram of CuO/ZnO junction has also been discussed to explore the charge transfer process across the interface.

Caking and characterizing graphene oxide thin films via electrodeposition technique for possible application in photoelectrochemical spliting of water

In the present study Readymade Graphene oxide (GO) has been coated using electrochemical deposition technique [1] on to the conducting glass (ITO) substrate. Raman spectra generated D and G Peaks obtained at 1346 and 1575 cm−1 confirmed the presence of GO [2]. The UV-Visible absorption measurements provided absorption peak at 262 nm and the Tauc plots yielded band-gap energy of sample around 3.9 eV. The PEC measurements involved determination of current-voltage (I-V) characteristics, both under darkness as well as under illumination. The photocurrent of 1.21 mA/cm−2 at 0.5 V applied voltage (vs. saturated calomel electrode), was recorded under the illumination of 150 Wcm−2 (Xenon arc lamp; Oriel, USA). The photocurrent values were utilized further to calculate applied bias photon-to-current efficiency (% ABPE), which was estimated to 0.98 % at 0.5 V bias.

Synthesis and Characterization of Fe2O3-ZnO Nanocomposites for Efficient Photoelectrochemical Splitting of Water

It is indispensable to construct clean energy systems in order to solve the current energy crisis issues. In the present work nanocomposite Fe2O3-ZnO powders have been prepared. XRD analysis revealed dominant evolution of wurtzite ZnO and α-Fe2O3 at Zn/Fe molar ratios being, respectively, ≥ 19.0 and ≤ 0.05. However, at intermediate concentrations, simultaneous growth of two oxides along with cubic ZnFe2O4 has been observed. Optical characterization led to prominent absorption threshold, which is shifted towards higher wavelength with increasing Fe amount. Results indicate that Fe2O3-ZnO nanocomposite at optimized Zn/Fe molar ratio yields significantly increased photoresponse compared to pure ZnO or Fe2O3.