| Summary: | Electrocatalytic reduction of carbon dioxide to produce usable products and fuels such as alkanes, alkenes, and alcohols, is a very promising strategy. Recent experiments have witnessed great advances in precisely controlling the synthesis of single atom alloys (SAAs), which exhibit unique catalytic properties different from alloys and nanoparticles. However, only certain precious metals, such as Pd or Au, can achieve this transformation. Here, the density functional theory (DFT) calculations were performed to show that Zn-based SAAs are promising electrocatalysts for the reduction of CO<sub>2</sub> to C<sub>1</sub> hydrocarbons. We assume that CO<sub>2</sub> reduction in Zn-based SAAs follows a two-step continuous reaction: first Zn reduces CO<sub>2</sub> to CO, and then newly generated CO is captured by M and further reduced to C<sub>1</sub> products such as methane or methanol. This work screens seven stable alloys from 16 SAAs (M = Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, V, Mo, Ti, Cr). Among them, Pd@Zn (101) and Cu@Zn (101) are promising catalysts for CO<sub>2</sub> reduction. The reaction mechanisms of these two SAAs are discussed in detail. Both of them convert CO<sub>2</sub> into methane via the same pathway. They are reduced by the pathway: *CO<sub>2</sub> → *COOH → *CO + H<sub>2</sub>O; *CO → *CHO → *CH<sub>2</sub>O → *CH<sub>3</sub>O → *O + CH<sub>4</sub> → *OH + CH<sub>4</sub> → H<sub>2</sub>O + CH<sub>4</sub>. However, their potential determination steps are different, i.e., *CO<sub>2</sub> → *COOH (ΔG = 0.70 eV) for Cu@Zn (101) and *CO → *CHO (ΔG = 0.72 eV) for Pd@Zn, respectively. This suggests that Zn-based SAAs can reduce CO<sub>2</sub> to methane with a small overpotential. The solvation effect is simulated by the implicit solvation model, and it is found that H<sub>2</sub>O is beneficial to CO<sub>2</sub> reduction. These computational results show an effective monatomic material to form hydrocarbons, which can stimulate experimental efforts to explore the use of SAAs to catalyze CO<sub>2</sub> electrochemical reduction to hydrocarbons.
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