Conformal coating of superhydrophilic nickel iron phytic acid complex to boost BiVO4 photoanode solar water oxidation

Abstract

The BiVO₄ photoanode holds a significant competitive edge for industrialization due to its high theoretical photocurrent density and solar-to-hydrogen conversion efficiency but is challenged by poor reaction kinetics and stability. Here, a conformal and superhydrophilic layer of phytic acid coordinated with nickel and iron (PA-NiFe) was in situ deposited on the surface of the BiVO₄ photoanode via a facile interfacial coordination assembly strategy. The BiVO₄@PA-NiFe photoanode achieved a high photocurrent density of 4.58 mA cm⁻² and a surface charge separation efficiency of 84.5%, which are 3.23 and 1.91 times higher than those of the pristine BiVO₄ photoanode, respectively. Moreover, the BiVO₄@PA-NiFe photoanode exhibited excellent durability during a 6-hour stability assessment. The enhanced surface charge separation and the improved potential-limiting step during the oxygen evolution reaction contribute to improved photoelectrochemical performances. This work underscores a competitive strategy for developing metal–organic complexes to advance the development of efficient photoanodes.