Integrative Ni1-Px Catalytic Pairs for Low-Concentration CO2 Electroreduction.

Abstract

The electrochemical CO2 reduction reaction (CO2RR) powered by renewable electricity offers a promising approach for sustainable carbon utilization. However, under industrially relevant low CO2 concentrations (5-15 vol.%), the efficiency and selectivity of electrochemical CO2RR are significantly constrained by the limited CO2 supply and the competitive hydrogen evolution reaction (HER). Herein, we report integrative Ni1-Px catalytic pairs (Ni1-Px/ICPs) that exhibit super CO2-to-CO conversion efficiency under low-concentration CO2 conditions. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and X-ray absorption spectroscopy (XAS) measurements show that P incorporation modulates the electrochemical microenvironment and accelerates reaction kinetics. H/D isotopic substitution experiments and theoretical calculations unveil a mechanistic transition from an Eley-Rideal to Langmuir-Hinshelwood pathway, enabled by cooperative adsorption on adjacent Ni and P sites. Notably, a hydrogen-bonded six-membered Ni-C-O-H-O-P-Ni ring forms between adsorbed CO2 and H2O, facilitating proton-coupled electron transfer and lowering the reaction barrier. This unique adsorption motif enhances CO2 activation, suppresses HER, and enables efficient CO generation at low CO2 concentrations. Our findings show the importance of atomically dispersed catalytic pairs for advancing carbon utilization and overcoming selectivity challenges in electrochemical hydrogenation.