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Electrocatalysis represents a promising method to generate renewable fuels and chemical feedstock from the carbon dioxide reduction reaction (CO 2 RR). However, traditional electrocatalysts based on transition metals are not efficient enough because of the high overpotential and slow turnover. MXenes, a family of two-dimensional metal carbides and nitrides, have been predicted to be effective in catalyzing CO 2 RR, but a systematic investigation into their catalytic performance is lacking, especially on hydroxyl (−OH)-terminated MXenes relevant in aqueous reaction conditions. In this work, we utilized first-principles simulations to systematically screen and explore the properties of MXenes in catalyzing CO 2 RR to CH 4 from both aspects of thermodynamics and kinetics. Sc 2 C(OH) 2 was found to be the most promising catalyst with the least negative limiting potential of −0.53 V vs RHE. This was achieved through an alternative reaction pathway, where the adsorbed species are stabilized by capturing H atoms from the MXene's OH termination group. New scaling relations, based on the shared H interaction between intermediates and MXenes, were established. Bader charge analyses reveal that catalysts with less electron migration in the *(H)COOH → *CO elementary step exhibit better CO 2 RR performance. This study provides new insights regarding the effect of surface functionalization on the catalytic performance of MXenes to guide future materials design.

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Aqueous zinc ion batteries are promising secondary batteries for next-generation electrochemical energy storage. In this work, we report a hybrid electrolyte system with 3 M Zn(OTf)2 as zinc salt and 1 M urea + 0.3 M LiOAc as hybrid solute additives for highly reversible aqueous zinc ion batteries. In this electrolyte system, partial coordinated water molecules of Zn2+ are replaced, and the original hydrogen bond network of the bulk electrolyte also suffers from interruption. Moreover, the introduction of lithium acetate solves the aggravated self-corrosion caused by urea on the one hand and inhibits the growth of dendrites through the electrostatic shielding effect on the other. Benefiting from this multifunctional synergistic effect, dendrite-free Zn plating/stripping for 600 h at 4.8 mA cm–2 (20% depth of discharge) and highly reversible plating/stripping at ∼99.7% Coulombic efficiency with a high cumulative plating capacity of 1600 mAh is achieved.

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