Atomically dispersed Au confined by oxygen vacancies in Au-θ-Al2O3/Au/PCN hybrid for boosting photocatalytic CO2 reduction driven by multiple built-in electric fields

A new Au-θ-Al2O3/Au/PCN hybrid is fabricated by the collaborative design strategy of active site and assembled structure, which achieves highly efficient photocatalytic CO2 reduction (CO2R) performance. The energy band structure of PCN is adjusted significantly owing to the strong coupling effect of Au-θ-Al2O3/Au nanosheets intercalated in PCN nanosheets. The result brings about up-shift of CB, VB and Fermi energy level overall and decrease of bandgap, which is in favor of harvesting visible light, exciting VB electrons and increasing reduction ability. In addition, the multiple built-in electric fields are induced by electron diffusion effect between structural units, due to the tight interface contact in the Au-θ-Al2O3/Au/PCN hybrid, which can effectively promote the separation of photoinduced charge carriers. Furthermore, the atomically dispersed Au atoms confined by the oxygen vacancies in Au-θ-Al2O3/Au can provide the plenty of effective active sites for CO2R reaction, and meanwhile, the localized surface plasmon resonance (LSPR) effect induced by Au nanoparticles on Au-θ-Al2O3/Au can improve the visible light response and produce abundant hot electrons to contribute to CO2R reaction. As a consequence, the average CO evolution rate of over the optimizing 10 %-Au-θ-Al2O3/Au/PCN hybrid (7.76 μmol g-1h−1) reaches up to 3.53 times than that of PCN (2.20 μmol g-1h−1) in the CO2R reaction, and maintains basically stable operation within 7 cycles of running, suggesting the superior activity and recyclability.