Regulated reaction pathway of CO2 photoreduction into CH4 by metal atom pair sites

The carbon dioxide (CO2) reduction process involves complex protonation, making the resulting product often unpredictable. To achieve the desired product, it is crucial to manipulate the reaction steps. Herein, we build the metal atom pair sites for selective CO2 photoreduction into methane. As a prototype, Ni atom pair sites loaded on the MoS2 nanosheets were synthesized and verified by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure spectra (XANES). In-situ Fourier transform infrared spectroscopy (FTIR) monitors the *CHO group, a crucial intermediate in CH4 production, during CO2 photoreduction on the Ni-MoS2 nanosheets, whereas this monitoring is not observed for the MoS2 nanosheets. Also, theoretical calculations disclose that over the Ni-MoS2 nanosheet slab, the formation energy of *CHO intermediates is determined to be lower (0.585 eV) than the desorption energy of *CO intermediates for CO production (0.64 eV), implying the higher selectivity of CH4 production. Accordingly, the Ni-MoS2 nanosheets demonstrate a methane formation rate of 27.21 mu mol<middle dot>g(-1)<middle dot>h(-1), coupled with an impressive electron selectivity of 94.2%.