Enhancing efficiency of Fe2O3 for robust and proficient solar water splitting using a highly dispersed bioinspired catalyst

Abstract

Fe2O3 is known to offer an encouraging approach to sustainable solar energy harvesting. However, fast charge recombination caused by short diffusion length and inefficient charge separation after photon absorption restrict its wide application. In our present work, attempts have been made to enhance the efficiency of Fe2O3 thin films by combatting the aforesaid problems by initially doping the samples with titanium, followed by fabrication of an efficient and robust cobalt acetate (Co-Ac) water oxidation catalyst. FE-SEM, EDAX, AFM, and Raman analysis for modified photoelectrodeposited catalyst samples, along with comparative electrochemical and photoelectrochemical studies (Nyquist studies, Tafel plots, Voc decay rate), were conducted in two different pH media (phosphate buffer, pH 8 and pH 12.5) to highlight the enhanced efficiency of the thus prepared modified photoanodes. Modified photoanode (Co-Ac/Ti–Fe2O3) systems yielded higher photocurrent density than pristine samples (Ti–Fe2O3). Photocurrent densities under one sun illumination were found to be up to 225% higher in pH 12.5 and about 190.5% higher in pH 8 buffering medium than pristine doped samples at 0.85V/SCE. Maximum photocatalytic activity is observed for 40 cycles of deposition of the catalyst, which is due to the extended lifetime of charge carriers of the photoelectrode, which has been experimentally verified by carrier lifetime estimation (with respect to Voc decay) in addition to minimum charge transfer resistance. Enhanced efficiency has been reported in terms of applied bias photon to current efficiency (ABPE), incident photon to current efficiency (IPCE), and Faradaic efficiency, along with turnover frequency, to support the high photocatalytic competence of the modified photoanode system for efficient water splitting and hydrogen generation.