Light Induced Water Oxidation on Cobalt-Phosphate (Co-Pi) Catalyst Modified Semi-Transparent, Porous SiO2-BiVO4 Electrodes

A facile and simple procedure for the synthesis of semi-transparent and porous SiO ₂-BiVO ₄ 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 SiO ₂-BiVO ₄ 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 SiO ₂-BiVO ₄ 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 SiO ₂-BiVO ₄.