Pulse laser annealing activates titanium-doped hematite photoanodes for photoelectrochemical water oxidation

Abstract

Efficient activation of donor-type dopants is important for promoting the photoelectrochemical (PEC) performance of semiconductor photoanodes. High temperature annealing, the most often-adopted method, can active the dopants, but is accompanied by serious deterioration of the conductive substrate. Hence, it still remains a challenge to develop a new method to activate the dopants in semiconductor photoanodes deposited on a substrate that is not resistant to high temperature. Herein, we report a pulse laser annealing (PLA) strategy to activate titanium dopant in hematite photoanodes at room temperature to improve the PEC performance for water splitting. A short treatment with 450 nm nanosecond yttrium aluminum garnet (YAG) laser (20 pulses, 30 mJ cm−2 per pulse) causes crystallinity improvement and surface roughening of hematite photoanodes without destroying the fluorine doped SnO2 (FTO) conductive glass substrate, and results in a 1.85-fold increased photocurrent density (0.484 mA cm−2, 1.23 V vs. RHE) of Ti-doped hematite photoanodes (5% doping level, Ti:Fe2O3-PLA). The charge transfer efficiency at the surface of Ti:Fe2O3-PLA was approximately two-fold higher than Ti:Fe2O3, and a 10.1-fold increased donor density (1.29 × 1019 cm−3) was achieved, demonstrating the potential of PLA treatment for activating doped semiconductor photoanodes at room temperature.