To What Extent Surface Morphology Can Influence the Photoelectrochemical Performance of Au:WO3 Electrodes?

Abstract

Considering hydrogen as a future fuel, development of clean energy sources based on solar power is the main human challenge in recent years. Here, for the first time, Au:WO3 photoanodes are synthesized with different Au concentrations and then applied for photoelectrochemical (PEC) water splitting. A comprehensive statistical study on the prepared photoanode surface is conducted to understand the correlation between surface morphology and PEC activity, using atomic force microscopy (AFM). The results clearly justified the maximum surface area observed for the film containing 1 mol % Au. Additionally, X-ray diffraction (XRD) analysis determined that Au nanocrystals have been formed in cubic structure with the size of 2952 nm. X-ray photoelectron spectroscopy (XPS) revealed that the presence of Au in a combined metal/oxide state strongly affects on the Au:WO3 photoanode performance. Photoresponse investigation of the synthesized films showed that the highest photocurrent was obtained for the sample containing 1 mol% gold with the maximum incident photon to current efficiency (IPCE) of about 20% at 360 nm wavelength. In addition, measuring the amount of hydrogen produced in the water splitting reaction supports the result that the sample containing 1 mol% Au exhibits the highest hydrogen production rate (similar to 3 mu mol/h) as compared to other samples.