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The construction of an environmentally friendly and efficient photocatalyst for water splitting and hydrogen evolution can effectively alleviate the pressure of current energy consumption and environmental pollution. Herein, by using first-principles calculations, the MoSiGeN4/SiC heterojunction was studied as a potential photocatalyst. According to different stacking methods, 12 kinds of configurations of such heterojunction with high symmetry were constructed, among which four kinds show excellent stability and hence were further studied. The results show that such heterojunction is Z-scheme heterojunction, which not only has good light absorption efficiency, but also shows excellent performance of photocatalytic water splitting for hydrogen evolution. In addition, one of the stable configurations shows better photocatalytic hydrogen evolution performance than precious metal catalyst Pt, and the Gibbs free energy is only −0.039 eV. It is expected to prepare a hydrogen evolution catalyst with excellent performance. Further, the possible mechanism responsible for the excellent properties of MoSiGeN4/SiC heterojunction in photocatalysis has been revealed. Our research further enriches the theoretical research genealogy of MA2X4 family materials and guides the direction for further rational design of photocatalysts. Schematic diagrams of all studied configurations, catalytic mechanism and HER performance characterization. [ABSTRACT FROM AUTHOR]

Finding efficient and environmentally friendly semiconductor photocatalysts can effectively alleviate the energy crisis and environmental pollution. Based on first-principles calculations, this work focused on the electronic, Bader charge and optical properties of the TMDs/MN heterojunctions. The results showed that the AlN/WS2 and GaN/WS2 heterojunctions are the type-II energy band arrangement, which indicates effective promotion of the separation of the photogenerated electron–hole pairs. Meanwhile, the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions belonged to the type-I energy band arrangement. The Bader charge results showed that the built-in electric field formed by the heterojunction prevents the recombination of charge carriers. These type-I heterojunctions have excellent optical absorption ability and are suitable for optoelectronic components. Surprisingly, we found that the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions transform type-I heterojunction to type-II heterojunction by applying electric field. This work further provides the theoretical basis for the design of efficient photocatalysts. [ABSTRACT FROM AUTHOR]