Utilizing Er-doped ZnIn₂S₄ for efficient photocatalytic CO₂ conversion

In the quest for effective photocatalysts for CO2 reduction, catalysts doped with rare-earth elements have garnered considerable attention due to their unique electronic structures and energy levels, which enable enhanced light absorption and charge transfer capabilities. In this study, we synthesized erbium-doped ZnIn2S4 using a hydrothermal method. Compared with pure ZnIn2S4, the erbium-doped variant displayed a significant boost in photocatalytic performance, improving the efficiency of CO2 reduction to methane by 256 times, with a selectivity exceeding 90 % towards methane. Through DFT analysis, we found that the doping of erbium introduced new energy levels into ZnIn2S4, effectively narrowing the band gap and thereby enhancing light absorption efficiency. Furthermore, our research revealed that erbium-doped ZnIn2S4 introduces a uniquely distinct reaction pathway for CO2 reduction compared to pure ZnIn2S4, significantly reducing the reaction barrier. Moreover, it enhances the adsorption of the key intermediate, *CHO and *CH2O, steering the reaction pathway towards the production of CH4. These findings not only offer valuable insights for the development of efficient and selective photocatalysts but also pave new avenues for research into CO2 conversion.