Novel p- and n-type S-scheme heterojunction photocatalyst for boosted CO₂ photoreduction activity

S-scheme photocatalysts are more efficient than the conventional type-II configuration, but the CO₂ reduction performances are still unsatisfactory. Herein, we firstly report the layered double hydroxide (LDH) based S-scheme heterostructure photocatalyst (NiIn LDH/In₂S₃) with n-type NiIn LDH and p-type In₂S₃. The built-in internal electric field directs the photogenerated electrons flow from the conductive band of In₂S₃ to the valance band of NiIn LDH, which is confirmed by operando and theoretical experiments. The CO₂ photoreduction intermediates are monitored by in-situ Raman spectra, and the density functional calculations disclose the reduced energy barrier for CO desorption on the heterojunction. Therefore, without cocatalysts or sacrificial agents, the NiIn LDH/In₂S₃ heterojunction delivers a high CO yield rate of 29.43 μmol g⁻¹ h⁻¹ under visible light irradiation, ca. 3.5 and 4.3 times higher than the single counterpart NiIn LDH and In₂S₃. Notably, this value is the highest among S-scheme CO₂ photocatalysts and surpasses most top-ranking benchmarks.