Surface modification of LaFeO3 by Co-Pi electrochemical deposition as an efficient photoanode under visible light

Abstract

LaFeO₃ is a promising visible light photocatalyst due to its favorable band gap and excellent stability in aqueous solution. The cathodic photocurrent for p-type characteristics reversing to anodic photocurrent on a LaFeO₃ photoanode is observed under visible light (>420 nm) and the anodic photoelectrochemical water oxidation performance is improved by electro-deposition of amorphous cobalt-phosphate (Co-Pi). It shows that the presence of Co-Pi down-shifts the onset potential by ∼560 mV for anodic photocurrent, and the improvement can be attributed to enhanced water oxidation due to the Co^II/Co^III-OH discharge in Co-Pi decorated layers by cyclic voltammetry test. The transition anodic photocurrent is improved by about six times after Co-Pi coating under visible light at 0.50 V vs. Ag/AgCl and the electrochemical impedance spectroscopy certifies the enhanced charge transfer, which contributes to the meliorative anodic photocurrent. The suppression of the photogenerated electron–hole recombination after Co-Pi coating on LaFeO₃ photoanode is directly demonstrated by the reduced photoluminescence spectrum. Combined with the accelerated carrier consumption on the surface and enhanced carrier separation on the photoanode, the incident photon-to-current conversion efficiencies of LaFeO₃ can be promoted from 1.37% to 2.14% at 400 nm owing to the presence of the Co-Pi layer.