Single-atom photocatalysis based on 2D fullerene structures for water splitting and CO2 reduction†

Carbon-based materials are promising photocatalyst candidates due to their high stability, rich redox properties, and high abundance on the earth. In this study, based on first-principles calculations, we systematically investigate the performance of single-atom catalysis with different metals in a two-dimensional (2D) semiconducting quasi-hexagonal phase C₆₀ network (qHP-C₆₀). Eleven metals which exhibit energetically stable doping are screened out as the candidates for single-atom catalysts in qHP-C₆₀. Our results show that single-atom doping with all the selected metals can extend the absorption of qHP-C₆₀ in the visible light range. More importantly, the doped metal atoms can modify the electronic states and reactivities of the C atoms nearby, providing more favorable reaction sites during different catalytic processes. As a result, the single-atom doping can significantly reduce the energy barriers of multiple reactions for qHP-C₆₀. Specifically, the Cs and Sr-doped qHP-C₆₀ monolayers exhibit extraordinarily low overpotentials of 0.010 and 0.43 V for the hydrogen evolution and oxygen evolution reactions, respectively. In addition, Sr-doped qHP-C₆₀ also exhibits an energy barrier as low as 0.46 eV for the C₁ products of CO, CH₃OH, and CH₄ in the CO₂ reduction reaction. Our results provide new insights into the structural engineering of high-efficiency multi-functional photocatalysts and the exploration of applications for 2D carbon-based materials.