Plasma-Induced Vacancy Defects in Oxygen Evolution Cocatalysts on Ta3N5 Photoanodes Promoting Solar Water Splitting

摘要

Surface recombination is a critical issue for tantalum nitride (Ta3N5)-based photoanodes in solar water splitting application. The efficient cocatalysts (Ni-, Fe-, and Co-based) have been developed to promote the electron-hole separation and transportation but still have limited success in some cases. Herein, we studied the Ar plasma-induced etching strategy on the pristine Ta3N5 nanotubes and Co(OH)(x)-decorated Ta3N5 nanotubes. The Ar plasma can not only destroy the recombination center (TaO) in the interface between the Ta3N5 and electrolyte, resulting in a fast charge transfer, but also most importantly generate more oxygen vacancies with a high ratio of Co2+/Co3+ and produce a higher surface area in the Co(OH)(x) cocatalyst. The more active sites on Ta3N5 and abundant oxygen vacancies on cocatalyst synergetically contribute to the enhanced solar water splitting activity, which give rise to a fast water oxidation reaction in the interface. The resulting photoanode shows double the performance improvement under AM 1.5G sunlight conditions. Interface-defect engineering is proven to be an efficient and facile strategy to enhance the solar water oxidation activity of Ta3N5, which highlights the advantages of the plasma-etching strategy for establishing the highly active cocatalysts on photoanodes in terms of the conversion of solar energy into chemical energy.