Electrochemical CO₂ conversion to methane, powered by intermittent renewable electricity, provides an entrancing opportunity to both store renewable electric energy and utilize emitted CO₂. Copper-based single atom catalysts are promising candidates to restrain C-C coupling, suggesting feasibility in further protonation of CO* to CHO* for methane production. In theoretical studies herein, we find that introducing boron atoms into the first coordination layer of Cu-N₄ motif facilitates the binding of CO* and CHO* intermediates, which favors the generation of methane. Accordingly, we employ a co-doping strategy to fabricate B-doped Cu-N_x atomic configuration (Cu-N_xB_y), where Cu-N₂B₂ is resolved to be the dominant site. Compared with Cu-N₄ motifs, as-synthesized B-doped Cu-N_x structure exhibits a superior performance towards methane production, showing a peak methane Faradaic efficiency of 73% at −1.46 V vs. RHE and a maximum methane partial current density of −462 mA cm⁻² at −1.94 V vs. RHE. Extensional calculations utilizing two-dimensional reaction phase diagram analysis together with barrier calculation help to gain more insights into the reaction mechanism of Cu-N₂B₂ coordination structure.

The removal of acetylene impurities remains important yet challenging to the ethylene downstream industry. Current thermocatalytic semihydrogenation processes require high temperature and excess hydrogen to guarantee complete acetylene conversion. For this reason, renewable electricity-based electrocatalytic semihydrogenation of acetylene over Cu-based catalysts is an attractive route compared to the energy-intensive thermocatalytic processes. However, active Cu electrocatalysts still face competition from side reactions and often require high overpotentials. Here, we present an undercoordinated Cu nanodots catalyst with an onset potential of −0.15 V versus reversible hydrogen electrode that can exclusively convert C₂H₂ to C₂H₄ with a maximum Faradaic efficiency of ~95.9% and high intrinsic activity in excess of −450 mA cm⁻² under pure C₂H₂ flow. Subsequently, we successfully demonstrate simulated crude ethylene purification, continuously producing polymer-grade C₂H₄ with <1 ppm C₂H₂ for 130 h at a space velocity of 1.35 × 10⁵ml g_cat⁻¹ h⁻¹. Theoretical calculations and in situ spectroscopies reveal a lower energy barrier for acetylene semihydrogenation over undercoordinated Cu sites than nondefective Cu surface, resulting in the excellent C₂H₂-to-C₂H₄ catalytic activity of Cu nanodots.

Proton exchange membrane water electrolysis stands as a promising technology for sustainable hydrogen production, although its viability hinges on minimizing platinum (Pt) usage without sacrificing catalytic efficiency. Central to this challenge is enhancing the intrinsic activity of Pt while ensuring the stability of the catalyst. We herein present a Mo₂TiC₂ MXene-supported Pt nanocluster catalyst (Mo₂TiC₂-Pt_NC) that requires a minimal Pt content (36 μg cm⁻²) to function, yet remains highly active and stable. Operando spectroscopy and theoretical simulation provide evidence for anomalous charge transfer from the MXene substrate to Pt_NC, thus generating highly efficient electron-rich Pt sites for robust hydrogen evolution. When incorporated into a proton exchange membrane electrolyzer, the catalyst affords more than 8700 h at 200 mA cm⁻² under ambient temperature with a decay rate of just 2.2 μV h⁻¹. All the performance metrics of the present Mo₂TiC₂-Pt_NC catalysts are on par with or even surpass those of current hydrogen evolution electrocatalysts under identical operation conditions, thereby challenging the monopoly of high-loading Pt/C-20% in the current electrolyzer design.

Using renewable electricity to convert CO₂ into CO offers a sustainable route to produce a versatile intermediate to synthesize various chemicals and fuels. For economic CO₂-to-CO conversion at scale, however, there exists a trade-off between selectivity and activity, necessitating the delicate design of efficient catalysts to hit the sweet spot. We demonstrate here that copper co-alloyed with isolated antimony and palladium atoms can efficiently activate and convert CO₂ molecules into CO. This trimetallic single-atom alloy catalyst (Cu₉₂Sb₅Pd₃) achieves an outstanding CO selectivity of 100% (±1.5%) at −402 mA cm⁻² and a high activity up to −1 A cm⁻² in a neutral electrolyte, surpassing numerous state-of-the-art noble metal catalysts. Moreover, it exhibits long-term stability over 528 h at −100 mA cm⁻² with an FE_CO above 95%. Operando spectroscopy and theoretical simulation provide explicit evidence for the charge redistribution between Sb/Pd additions and Cu base, demonstrating that Sb and Pd single atoms synergistically shift the electronic structure of Cu for CO production and suppress hydrogen evolution. Additionally, the collaborative interactions enhance the overall stability of the catalyst. These results showcase that Sb/Pd-doped Cu can steadily carry out efficient CO₂ electrolysis under mild conditions, challenging the monopoly of noble metals in large-scale CO₂-to-CO conversion.