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Methane (CH4), the main component of natural gas, is one of the most valuable products facilitating energy storage via electricity conversion. However, the poor selectivity and high overpotential for CH4 formation with metallic Cu catalysts prevent realistic applications. Introducing a second element to tune the electronic state of Cu has been widely used as an effective method to improve catalytic performance, but achieving high selectivity and activity toward CH4 remains challenging. Here, we successfully synthesized Cu-Bi NPs, which exhibit a CH4 Faradaic efficiency (FE) of as high as 70.6% at −1.2 V vs reversible hydrogen electrode (RHE). The FE of Cu-Bi NPs has increased by approximately 25-fold compared with that of Cu NPs. DFT calculations showed that alloying Cu with Bi significantly decreases the formation energy of *COH formation, the rate-determining step, which explains the improved performance. Further analysis showed that Cu that has been partially oxidized due to electron withdrawal by Bi is the most possible active site.

Renewable methane synthesized via CO2 electroreduction has the potential to serve as a carbon-neutral medium benefiting from its high energy density. However, challenges remain in achieving high selectivity for electromethanation with low energy input. Here, we found that the adhered ligands on the copper surface can modulate the local microenvironment to realize high rates for methane electrogeneration. The designed glutathione-modified copper electrode exhibited an impressive CO2 to CH4 Faradaic efficiency of 61.7% with a partial current density of 153.7 mA cm–2, which was 35-fold higher than that of pristine copper. Operando Raman spectroscopy experiments suggest that the carboxyl and amino groups of glutathione ligands play a crucial role in regulating intermediate configurations and local proton availability. More broadly, these findings offer routes to alter surface reactivity and create a platform for designing highly selective CO2 electroreduction catalysts.

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