Asymmetric Ti-O-Cu bridge synergized with amorphous MXene to boost glycerol oxidation and hydrogen evolution

Glycerol oxidation reaction (GOR) is a mild, sustainable pathway with great potential for producing high-value chemicals such as formic acid (FA). Integrating GOR with hydrogen evolution reaction (HER) circumvents the high energy barrier of anodic oxygen evolution in traditional water splitting. However, achieving selective CC bond cleavage in glycerol-to-FA conversion remains a major technical and scientific challenge. Here, via the Ostwald ripening mechanism, size-tunable cuprous oxide nanocubes are in-situ grown on amorphous MXene (Cu₂O/AMXene), creating well-defined dual active sites with clear functional division: electron-rich Cu⁺ for GOR and Ti sites for HER. The optimized Cu₂O-0/AMXene (28 nm Cu₂O) delivers a HER overpotential of 32 mV at 10 mA cm^-2, a GOR potential of 1.13 V at 10 mA cm^-2, and a full electrolyzer voltage of 1.31 V, while maintaining excellent catalytic efficiency after 150 h of continuous operation. Cu₂O growth induces MXene amorphization, generating edge ligand-unsaturated Ti sites that enhance water dissociation for proton supply, while Ti⁴⁺ promotes hydrogen spillover to transfer protons to Ti³⁺ for efficient HER. Electron-rich Cu⁺ forms asymmetric Ti-O-Cu interactions via electron donation from AMXene, enhancing orbital overlap with p orbitals of glycerol oxygen atoms for GOR. This electron-rich environment inhibits Cu⁺ oxidation to Cu²⁺ at high anodic potentials, stabilizing the active s-p hybrid configuration. This work also highlights the critical role of O-functional groups on AMXene and lattice O atoms in Cu₂O for strengthening metal-support interactions.