Boosting the stability and photoelectrochemical activity of a BiVO4 photoanode through a bifunctional polymer coating

Abstract

Low stability of photoanodes in electrolytes, especially in alkaline electrolytes, greatly limits their practical applications. Therefore, it is highly meaningful to develop a strategy to stabilize photoanodes under strongly alkaline conditions. Herein, a metal-free poly(p-phenylene pyromellitimide) film is coated onto a BiVO₄ photoanode as a bifunctional catalyst layer and protective layer by in situ thermal polymerization. Structural characterization shows that the polymer film can effectively protect the BiVO₄ semiconductor. Photoelectrochemical studies verify that the polymer film can improve the efficiency of the surface-reaching hole reaction and promote the separation of surface carriers. Thus, the polymer-coated photoanode shows a superior photoelectrochemical activity, which is 2.5 times higher than that of the pristine photoanode. Meanwhile, the polymer-coated photoanode also exhibits excellent stability in neutral and alkaline electrolytes. The photocurrent remains above 70% even after a six-hour reaction in a strongly alkaline electrolyte. This work provides a simple solution to stabilize semiconductor photoanodes under alkaline conditions for efficient photoelectrochemical applications.