Surface modification of LaFeO3 by Co-Pi electrochemical deposition as an efficient photoanode under visible light†
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 CoII/CoIII-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.