Large-Current CO2 Electromethanation Through Active Hydrogen Regulation Over Carbon Nitride.

Abstract

Electromethanation of CO2 has received intensive attention due to its high calorific value and convenient storage along with transportation to accommodate industrial demands. However, it is limited by sluggish multi-step proton-coupled electron transfer kinetics and undesired *H coupling under high current density, posing great challenges to its commercialization. Herein, carbon nitride (CN) with superior hydrogen adsorption ability is used as an active-hydrogen adsorption and supply material. Through a facile liquid-assisted exfoliation and electrostatic self-assembly strategy to strengthen its interfacial contacts with Cu2O catalysts, yielding a strengthened CH4 production 52 times higher than that of pristine Cu2O. Flow-cell test ultimately achieved FECH4 and remarkably CH4 partial current density of 61% and 561mAcm-2, respectively. With in situ ATR-FTIR spectra and DFT calculations, it is established that strengthened interfaces enabled abundant *H tethered by ─C─N═C─ sites in CN nanosheets and oriented to the *CO hydrogenation to *CHO and *CHx on Cu species. This work reveals the profound influence of fine-expanded interfaces with dimensional materials on the product distribution and yield through the active-hydrogen management, which is of reference value for other small-molecule electro-polarization dominated by the proton-coupled electron transfer (PCET) process (e.g., N2, O2, etc.).