Construction of novel PG/GeP2 and PG/SiP2 vdW heterostructures for high-efficiency photocatalytic water splitting

The development and design of environmentally friendly, low-cost efficient visible-light-driven water splitting photocatalysts is a kind of the most promising methods to solve current energy shortage problems. Herein, the brand new penta-graphene/GeP2 (PG/GeP2) and PG/SiP2 van der Waals (vdW) heterostructures are constructed. Their geometric structures, thermodynamic feasibilities, and optoelectronic properties for water splitting are systematically investigated through DFT calculation. The results show that the band-gap value and band-edge positions prove these heterostructures are promising candidates for water splitting. Meanwhile, The Gibbs free energy change proves that the water-splitting progress is spontaneous. Especially, PG/GeP2 has a type-II band alignment and an indirect bandgap of 2.63 eV, and the electrical properties of PG/GeP2 heterostructure under-2% strain are adjusted to better catalyze the water-splitting reaction, improve the light absorption charac-teristic and effective mass of carrier. The unique band alignment of these heterostructures photocatalysts leads to high solar-to-hydrogen energy conversion efficiencies up to 10.8%, which has a good commercial application prospect. Therefore, these studies predict that PG/GeP2 vdW heterostructure is important candidates as photo -catalysts for overall water splitting.