Proton-Coupled Electron Transfer on CuO/TiCT MXene for Propane (CH) Synthesis from Electrochemical CO Reduction.

Electrochemical CO reduction reaction (CORR) to produce value-added multi-carbon chemicals has been an appealing approach to achieving environmentally friendly carbon neutrality in recent years. Despite extensive research focusing on the use of CO to produce high-value chemicals like high-energy-density hydrocarbons, there have been few reports on the production of propane (CH), which requires carbon chain elongation and protonation. A rationally designed 0D/2D hybrid CuO anchored-TiCT MXene catalyst (CuO/MXene) is demonstrated with efficient CORR activity in an aqueous electrolyte to produce CH. As a result, a significantly high Faradaic efficiency (FE) of 3.3% is achieved for the synthesis of CH via the CORR with CuO/MXene, which is ≈26 times higher than that of Cu/MXene prepared by the same hydrothermal process without NHOH solution. Based on in-situ attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and density functional theory (DFT) calculations, it is proposed that the significant electrocatalytic conversion originated from the synergistic behavior of the CuO nanoparticles, which bound the *C intermediates, and the MXene that bound the *CO coupling to the C intermediate. The results disclose that the rationally designed MXene-based hybrid catalyst facilitates multi-carbon coupling as well as protonation, thereby manipulating the CORR pathway.