MoS₂ Grain Boundary-Supported Single-Atom Catalysts for Efficient Electrocatalytic CO₂ Conversion to CO

Developing high-efficiency single-atom catalysts (SACs) is essential for the carbon dioxide reduction reaction (CO₂RR) to produce fuels and chemicals, yet achieving optimal performance remains challenging. In this work, we applied a grain boundary (GB) strategy to rationally design a series of MoS₂ supported SACs for electrocatalytic CO₂RR. Concretely, different 3d transition metal (TM) atoms were respectively anchored at three types of MoS₂ GBs (e.g., 5|7, 8|8, and 4|8 GBs) to form various TM@GB SACs. Our density-functional theory (DFT) calculations revealed that, in comparison with the MoS₂ perfect monolayer, strong interactions between TM atoms and MoS₂ GBs shift down the d-band center of these atoms, hence improving the CO₂RR activity of TM@GB SACs. Among TM@GBs, V@5|7, Cr@8|8, and V@4|8 GBs were demonstrated to possess excellent catalytic activity, enabling spontaneous CO₂ reduction to CO at applied electrode potentials of -0.30, -0.10, and -0.26 V (vs SHE), respectively. Further, a pivotal descriptor (ψ) based on the inherent structural properties of GB and TM was proposed to correlate the structure with the CO₂RR activity. Our findings highlight the potential of GB engineering as a strategic tool for modulating the properties of SACs, broadening the applications in catalyst design and optimization.