Solar Water Splitting By Transition Metal Oxide – Silicon Photoanodes Prepared under Cathodic Electrochemical Conditions

Abstract

Photo-assisted water splitting represents a pivotal strategy for realization of the hydrogen economy of the future. In this approach, the preparation of stable and efficient photoanodes is challenging due to the susceptibility of sensitive semiconductors to photocorrosion. Here, we demonstrate a metalorganic electrochemical approach by which amorphous transition metal oxides are formed on silicon under cathodic electrochemical conditions. This approach makes anti-corrosive interlayers potentially superfluous and realizes an oxide-silicon heterostructure with enhanced activity for the light-induced oxygen evolution reaction in alkaline electrolytes. Exemplifying analysis of electronic and optical properties is provided for a nickel oxide / silicon heterojunction. Interface engineering is demonstrated by formation of nanoscopic Au-Si heterocontacts acting as rectifying nanoemitters for light-induced holes toward the electrocatalytic nickel oxide layer.