Enhancing the Visible Light Photoelectrochemical Water Splitting of TiO₂ Photoanode <i>via</i> a p–n Heterojunction and the Plasmonic Effect

Abstract

Developing visible light-responding photoelectrocatalysts with higher efficiency is highly demanded and broadly concerned in terms of photoelectrochemical (PEC) water splitting. Here, we report that by constructing a TiO2/CuInS2 p–n junction and further decorating it with plasmonic Cu nanoparticles, the synthesized TiO2/CuInS2/Cu photoanodes show significantly enhanced visible light absorption and higher photoelectrocatalysis efficiency, benefiting from the joint influence of the built-in electric field and surface plasmonic resonance (SPR). Under >420 nm light irradiation, the photocurrent density is 2.36 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE), enhanced by about 10 times than that of pure TiO2. Furthermore, the hydrogen production rate was enhanced from an undetectable level to 4.552 μmol/cm2/h. Our results exhibit that the strategy of a double-layer co-catalyst has promising applications in water splitting and other solar energy-conversion areas.