《Rare Metals》: Regulated Reaction Pathway of CO₂ Photoreduction into CH₄ by Metal Atom Pair Sites

Dongpo He,⁺ Guangbing Huang,⁺ Jun Hu,⁺ Yang Wu, Xiaodong Li,^* Qingxia Chen,^* Shan Zhu, Wensheng Yan, Junfa Zhu, Yang Pan,  Xingchen Jiao^*

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, verified by the high-resolution transmission electron microscopy image, X-ray photoelectron spectroscopy, and X-ray absorption near edge structure spectra. In situ Fourier transform infrared spectroscopy 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 the formation energy of *CHO intermediates was determined to be lower (0.585 eV) than the desorption energy of *CO intermediates for CO production (0.64 eV) over the Ni-MoS₂ nanosheet slab, implying the higher selectivity of CH₄ production. Accordingly, the Ni-MoS₂ nanosheets demonstrate a methane formation rate of 27.21 μmol g^–1 h⁻¹, coupled with an impressive electron selectivity of 94.2%.

Figure 1. Schematic illustration for CO₂ photoreduction into CH₄ over the catalyst with metal pair sites.