Synergetic Role of Thermal Catalysis and Photocatalysis in CO2 Reduction on Cu2/MoS2

Effective activation of CO₂ is a primarily challenging issue in CO₂ reduction to value-added hydrocarbon chemicals, due to the large energy gap between the highest-occupied and lowest-unoccupied molecular orbitals (HOMO-LUMO). Here, we employ state-of-the-art first-principles calculations to explore the synergetic role of thermal catalysis and photocatalysis in CO₂ reduction, on typical single-atom scale catalyst, i.e., Cu₂ magic cluster on a semiconducting two-dimensional MoS₂ substrate. It is identified that only about 1% of the hot electrons excited from the MoS₂ substrate by at least 6.3 eV photons may be trapped by the inert CO₂ molecule at the expense of 400 fs. Moreover, the physisorption-to-chemisorption transition of CO₂ can be observed within 500 fs upon overcoming an about 0.05 eV energy barrier. Contrastingly, upon chemisorption, the activated CO₂^δ- species may trap about 7% of the hot electron excited from the MoS₂ substrate by about 2.5 eV visible photons, with a cost of 140 fs.