Improvement of Visible-Light Photocatalytic Efficiency in a Novel InSe/Zr2CO2 Heterostructure for Overall Water Splitting

The unexpected visible-light absorption, low recombination of electron–hole pairs, and high carrier mobility are found in a novel two-dimensional (2D) InSe/Zr2CO2 van der Waals heterostructure for overall water splitting photocatalysis. The photocatalytic mechanism has been systematically investigated using first-principles calculations for the first time. We prove that the 2D InSe/Zr2CO2 heterostructure is a robust and promising visible-light photocatalyst with several distinct advantages, as follows. It has a direct band gap of 1.81 eV, which is a more favorable band gap for visible-light photocatalysis. Its type-II band alignment directly leads to a significant electron–hole separation with electrons (holes) localized in the InSe (Zr2CO2) monolayer. The indirect band gap of the InSe (Zr2CO2) monolayer further suppresses the electron–hole recombination in it. Naturally, the recombination of the photogenerated electrons and holes is greatly suppressed in the InSe/Zr2CO2 heterostructure, which improves the solar energy utilization effectively. Moreover, a large optical absorption coefficient (105 cm–1) has been confirmed in the 2D InSe/Zr2CO2 heterostructure with the electron (hole) mobility reaching up to 104 (103) cm2 V–1 s–1, which is highly beneficial and desirable for enhancing its photocatalytic efficiency.