Morphological influence of electrode/electrolyte interface towards augmenting the efficiency of photoelectrochemical water splitting – A case study on ZnO

Abstract The present study is aimed towards calculating the magnitude of inherent surface morphological parameters of a rough metal oxide semiconductor. These surface parameters viz. fractal dimension, lower and upper cut off length scale play an important role in controlling and predicting the electrochemical response which can be determined using Power spectral density analysis utilizing Field emission-scanning electron microscopy and Atomic force microscopy images. Nanostructured ZnO thin films of varying layers are prepared by spin coating technique. Among which the sample with five layers is found to possess maximum morphological roughness with fractal dimension, lower and upper cut off length scale values 2.50, 15.49, 102.33 and 2.45, 12.58, 112  nm for untreated samples which changed to 2.39, 19.05, 135.49 and 2.28, 19.90, 150  nm after undergoing electrochemical treatment for Atomic force microscopy and Field emission-scanning electron microscopy images respectively. Furthermore, sample under consideration exhibits highest photocurrent density of 4.54 mA/cm 2 at 1.2 V vs Reversible Hydrogen Electrode in comparison to other prepared samples with varied layers deposition. The study correlates morphological parameters with the electrochemical and photoelectrochemical results and thus explains the role of morphology on the semiconductor/electrolyte interface.