Light induced water oxidation on cobalt-phosphate (Co–Pi) catalyst modified semi-transparent, porous SiO2–BiVO4 electrodes

Abstract

A facile and simple procedure for the synthesis of semi-transparent and porous SiO₂–BiVO₄ electrodes is reported. The method involves a surfactant assisted metal–organic decomposition at 500 °C. An earth abundant oxygen evolution catalyst (OEC), cobalt phosphate (Co–Pi), has been used to modify the SiO₂–BiVO₄ electrode by electrodeposition (ED) and photoassisted electrodeposition (PED) methods. Modified electrodes by these two methods have been examined for light induced water oxidation and compared to the unmodified SiO₂–BiVO₄ electrodes by various photoelectrochemical techniques. The PED method was a more effective method of OEC preparation than the ED method as evidenced by an increased photocurrent magnitude during photocurrent-potential (I–V) characterizations. Electrode surfaces catalyzed by PED exhibited a very large cathodic shift (∼420 mV) in the onset potential for water oxidation. The chopped-light I–V measurements performed at different intervals over 24-hour extended testing under illumination and applied bias conditions show a fair photostability for PED Co–Pi modified SiO₂–BiVO₄.