Efficient ambient ammonia synthesis by Lewis acid pair over cobalt single atom catalyst with suppressed proton reduction

Abstract

© Royal Society of Chemistry 2022. Improving the ammonia yield and Faraday efficiency of ambient electrochemical nitrogen fixation is a priority for altering the energy-intensive Haber-Bosch process. In this work, positively charged single cobalt atoms anchored on sponge-like nitrogen-doped mesoporous interconnected hollow carbon nanofibers (serving as a Lewis acid pair) were intentionally designed as catalytic centers that can suppress the side effect of the competing hydrogen evolution reaction and simultaneously boost the electrochemical conversion of nitrogen (N-2) to ammonia (NH3). The Lewis acid pair catalyst exhibits an NH3 production rate of 67.6 mu g h(-1) mg(-1) and a maximum Faraday efficiency of 56.9% at a peak potential of -0.1 V vs. RHE, which outperforms previously reported nitrogen reduction reaction (NRR) catalysts. First-principles DFT calculations suggest the regulation of the local electronic structure that induces Lewis acid pair formation upon charge transfer between the single Co atom and substrate, confirming a high intrinsic NRR by both experiments and theoretical calculations.