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[Display omitted] • Mo-based MXene is first applied as a cathode catalyst for Li-CO 2 batteries. • An innovative surface modification strategy, mild oxidation by CO 2 , is employed. • The catalyst optimizes the growth and decomposition of discharge products. • This MoO 2 @Mo 2 C-based Li-CO 2 battery outperforms most other MXene-based catalysts. The lithium-carbon dioxide (Li-CO 2) batteries hold promise for energy storage, given their capacity to capture and convert carbon dioxide (CO 2). However, the practical application of Li-CO 2 batteries continues to face substantial obstacles caused by sluggish CO 2 reduction/evolution kinetics, resulting in high overpotential and short lifespan. This work presents the fabrication of a highly effective MoO 2 @Mo 2 C heterostructure hybrid catalyst using a CO 2 oxidation strategy. This strategy integrated (in-situ) MoO 2 onto the surface of two-dimensional (2D) Mo 2 C MXene, enhancing catalytic activity while preserving 2D electron/ion pathways. As a result, the MoO 2 @Mo 2 C, when used as a catalyst in Li-CO 2 battery showcased a discharge capacity of 20790.8 mAh g−1 at a current density of 200 mA g−1. Notably, it achieved a long cycling life of 230 cycles at a cutoff capacity of 1000 mAh g−1 with a voltage gap as low as 1.85 V, which was significantly superior to that of a pristine Mo 2 CT x catalyst (3.61 V after twenty cycles). This work provides critical insights into the design of MXenes-based high-performance catalysts for advanced Li-CO 2 batteries. [ABSTRACT FROM AUTHOR]

ORR: oxygen reduction reaction; SMSI: strong metal-support interaction; LABI: Lewis acid-base interaction. [Display omitted] • Residual Zn in various ZIF-8 derived carbons could reach ∼10 wt%. • ZnN x could act as 'spatial barriers' suppressing Pt forming ORR inactive PtN x. • ZnN x could serve as Zn source for the intermetallation of L1 0 -PtZn. • ZnN x could bring the SMSI between PtZn and support. • LABI between ZnN x and PtCl 6 2− could promote the dispersion of PtZn. ZIF-8 derived carbons demonstrate admirable application prospects in electrocatalytic fields, while ZnN x remaining in those materials are overlooked, crippling the validity of theoretic studies in researches. Herein, the residual Zn in ZIF-8 derived carbons are found could exceed 10 wt% even at carbonization temperatures over 900℃, and Zn-NCs with various Zn contents are adopted as supports to synthesize low-platinum ORR catalysts. Substantial characterizations manifest that ZnN x in Zn-NC can not only provide Zn source for L1 0 -PtZn intermetallic, but act as 'spatial barriers' to prevent the formation of inactive PtN x , elevating the active Pt proportion in catalyst by ∼104%. The resultant Zn-NC-Ar-PtZn exhibits a mass activity of 0.557 mA/g Pt and a peak density of 1.485 W/cm2. DFT calculations show the strong thermodynamic tendency of forming PtN 4 without the protection of ZnN 4 , and the superior durability and activity of Zn-NC-Ar-PtZn should be attributed to its Zn-derived ligand effects and the SMSI. [ABSTRACT FROM AUTHOR]