Photoelectrochemical Oxygen Evolution Reaction Activity of Amorphous Co-La Double Hydroxide-BiVO4 Fabricated by Pulse Plating Electrodeposition

Strategically integrating semiconducting films with an efficient water oxidation catalyst to reduce charge recombination and improve the photocurrent is the bottleneck in photoelectrochemical (PEC) water splitting. Amorphous catalysts, especially the mixed metal oxides/hydroxides, show better stability and activity because of their unique morphology. Facile, reproducible synthesis of these catalysts by a simple method has been problematic. In this Letter, we show for the first time the application of pulse plating to synthesize amorphous Co-La mixed double hydroxide (MDH) on BiVO4/FTO (FTO, flourine-doped tin oxide). The method provides better adhesion and uniform deposits with controlled composition and grain size and facilitates fast charge transport, while lowering the charge recombination at the interface of the electrolyte and the semiconductor. With respect to BiVO4, reduction in onset potential by 0.53 V as well as 2.7 and 33.4 times increment in photocurrent density (J) at 1.23 V and the lower potential 0.6 V, respectively, obtained by BiVO4/MDH is noteworthy. The results obtained here suggest the possibility of using BiVO4/MDH in PEC cells and photoelectrochemical diodes.