Lanthanide-based photocatalysts for CO2 conversion: Are they a better choice for realizing sustainability?

Employing photocatalysis to diminish CO₂ concentrations when exposed to visible spectrum illumination, converting it into energy materials and chemical products, is an effective method to achieve carbon cycling. Among the many catalysts, lanthanide-based metals, with gradually filling 4f orbitals that give them unique electronic structures, have garnered significant focus on the domain of decreasing CO₂ via photocatalytic methods. Lanthanide metals exhibit a 4f orbital shielding effect, meaning that the f-electrons neither engage in atomic interactions or have substantial orbital convergence with ligands. This minimizes the influence of the external environment on the outer electrons, allowing lanthanide-based catalysts to remain stable. This distinctive property also helps increase surface defects in the catalyst, forming charge bridges or heterojunctions that promote rapid electron transfer and inhibit the reunion of electrons and vacancies. To fully harness the photogenerated electrons in photocatalytic CO₂ reduction. However, as a result of the Laporte selection rule, the kinetic functionality of lanthanide metals is somewhat restricted and requires sensitization by other components. Therefore, understanding and designing the regulatory mechanisms of lanthanide metals is a notable area that warrants further investigation and analysis. Unfortunately, comprehensive reports in this field remain quite limited. Against this backdrop, this paper primarily summarizes the latest developments in lanthanide-based catalysts for CO₂ reduction. It concentrates on the regulatory mechanisms of different lanthanide elements in the CO₂ reduction method and elucidates the reduction mechanisms. Various photoelectrochemical tests, such as Transient Absorption Spectroscopy (TAS) and Synchrotron X-ray Diffraction (SXRD), have also confirmed that lanthanide catalysts can boost the efficiency of CO₂ mitigation. Lastly, the challenges facing lanthanide catalysts within the sphere of photocatalytic CO₂ reduction are discussed, and recommendations for future research directions are provided.