Photoelectrochemical water oxidation in α-Fe2O3 thin films enhanced by a controllable wet-chemical Ti-doping strategy and Co–Pi co-catalyst modification

Abstract

The poor electrical conductivity, short hole diffusion length, and slow water oxidation reaction kinetics have severely limited the photoelectrochemical performance of the hematite (α-Fe2O3) photoanodes. In this paper, we report a facile wet-chemical approach to prepare the Ti-doping controllable hematite photoanode with subsequent Co–Pi electrocatalysts modification for solar water splitting. By optimizing the Ti-doping in Fe2O3, the Ti–Fe2O3 photoanodes can retain the primary morphology with the pristine Fe2O3 nanostructures, while simultaneously reducing the photogenerated charge carrier recombination rate in the films. Besides, by further decorating with Co–Pi co-catalysts on Ti–Fe2O3 surface, the formed Ti–Fe2O3/Co–Pi photoanode demonstrated an accelerated electrode/electrolyte kinetics during photoelectrochemical water oxidation reaction. As expected, the Ti–Fe2O3/Co–Pi photoanode produced an improved photocurrent density of 0.76 mA/cm2 at 1.23 V vs RHE, which is much higher than the photocurrent density of individual Fe2O3 (0.25 mA/cm2) and Ti–Fe2O3 photoanode (0.51 mA/cm2). This work provides a good insight for designing the composite photoanode to simultaneously enhance the charge transport and surface water oxidation kinetics for efficient solar fuel production.