Improved carriers transfer dynamics through dual-functional charge trapping and electronic tailoring for photocatalytic hydrogen production

The rapid charge carrier recombination and limited dynamics of reduction reaction are practical obstacles restricting the development and application of carbon nitride photocatalyst. To solve the problems, herein, we employ Ni and CoO nanodots, which possess reduction and oxidation cocatalytic effects, respectively, onto the surface of the t carbon nitride to promote the spatial separation of electrons and holes. The optimized metal-metal oxide composite supported photocatalyst achieves a photocatalytic hydrogen evolution rate of 1780 μmol h⁻¹ ·g⁻¹ under visible light (λ ≥ 420 nm). In situ spectroscopy, carrier dynamics analysis and calculation results reveal that the excellent photocatalytic activity is mainly attributed to a dual-functional mechanism, in which Ni nanodots act as electron acceptors and active sites to selectively accumulate photogenerated electrons, while CoO nanodots trap photogenerated holes as hole reservoirs, thus effectively achieving the fast charge separation. Meanwhile, under the synergistic interplay of Ni nanodots and CoO nanodots, the coupled Ni₁-PCN-CoO₀.₅ exhibits a d-band center tuned to a more favorable position for catalysis, lowering the energy barrier of adsorption/desorption of *H intermediates, accelerating reaction dynamics greatly. This work offers an insight into constructing precious-metal-free photocatalytic systems towards photocatalytic hydrogen production.