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.