Erbium Single Atom Composite Photocatalysts for Reduction of CO2 under Visible Light: CO2 Molecular Activation and 4f Levels as an Electron Transport Bridge

It is still challenging to design a stable and efficient catalyst for visible-light CO2 reduction. Here, Er3+ single atom composite photocatalysts are successfully constructed based on both the special role of Er3+ and the special advantages of Zn2GeO4/g-C3N4 heterojunction in the photocatalysis reduction of CO2. Especially, Zn2GeO4:Er3+/g-C3N4 obtained by in situ synthesis is not only more conducive to the tight junction of Zn2GeO4 and g-C3N4, but also more favorable for g-C3N4 to anchor rare-earth atoms. Under visible-light irradiation, Zn2GeO4:Er3+/g-C3N4 shows more than five times enhancement in the catalytic efficiency compared to that of pure g-C3N4 without any sacrificial agent in the photocatalytic reaction system. A series of theoretical and experimental results show that the charge density around Er, Ge, Zn, and O increases compared with Zn2GeO4:Er3+, while the charge density around C decreases compared with g-C3N4. These results show that an efficient way of electron transfer is provided to promote charge separation, and the dual functions of CO2 molecular activation of Er3+ single atom and 4f levels as electron transport bridge are fully exploited. The pattern of combining single-atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity.

Automated summary

A stable and efficient catalyst for visible-light CO2 reduction, Er3+ single atom composite photocatalysts Zn2GeO4:Er3+/g-C3N4, enhances catalytic efficiency by more than five times compared to pure g-C3N4, without sacrificial agents. The pattern of combining single-atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity, providing an efficient way of electron transfer to promote charge separation.