Single Atom Cu-Mediated Efficient Z-Scheme Photocatalytic CO₂ Conversion of TiO₂ Hetero-Phase Assembly

Constructing metal single-atom-mediated Z-scheme charge transmission is a promising yet challenging avenue to realize efficient solar photocatalysis. Here, a single-atom Cu-bridged TiO₂ hetero-phase assembly with opened cavities and Z-scheme charge transmission is fabricated via the illumination-assisted preparation recipe. When tested for gas-solid photocatalytic CO₂ conversion, our photocatalyst displays an extraordinary activity with CH₄ production rate reaching to 327.19 µmol·g^-1·h^-1, roughly 15.6 and 122.1 times enhancement than Degussa P25 TiO₂ and TiO₂(B), and it outperforms those of Cu nanoparticles, Pd single atoms, Pt nanoparticles, Pd nanoparticles, and Au nanoparticles-loaded counterparts as well as most TiO₂-based composites ever reported. Based on the experimental test and theoretical calculation results, Cu single atoms act as the mediator to enhance interfacial charge transfer, which changes the photo-carrier transmission pathway from type-II to Z-scheme, accounting for the significant promotion of photocatalytic capability. The study results could propel the marked optimization of photocatalytic efficiency by steering Z-scheme charge transport with a single-atom mediator.