Adjusting the catalytic activity of C2N/SiH heterojunction for water splitting: A first-principles study

The development and design of environmentally friendly, low-cost catalysts for water splitting is one of the most promising methods to solve current environmental problems. The C2N/SiH heterojunction is proposed and its geometric structure, electronic structure and thermodynamic feasibility for water splitting is systematically studied based on first-principles. The results show that the heterojunction is type-Ⅱ band alignment, which promotes the effective separation of electron-hole. The built-in electric field will further hinder the electron-hole recombination, thereby further improving the photocatalytic efficiency. It is worth noting that the electronic and thermodynamic properties of the heterojunction can be adjusted by applying uniaxial and biaxial strain to achieve better catalytic water splitting. It is indicated that a biaxial strain of −2% is recommended to adjust the catalytic efficiency of the hydrogen evolution reaction (HER), and a biaxial strain of 4% is recommended to adjust the catalytic efficiency of the oxygen evolution reaction (OER). In short, the research not only provides fundamental understanding for the water splitting of C2N/SiH heterojunction, but also provides a direction for improving the OER and HER catalytic activity of the heterojunction.