P-tuned FeN2 binuclear sites for boosted CO2 electro-reduction

Abstract

The recycling of CO2 through electrochemical processes offers a promising solution for alleviating the greenhouse effect; however, the activation of CO2 and desorption of *CO in electrocatalytic CO2 reduction (ECR) frequently encounter high energy barriers and competitive hydrogen evolution reactions (HERs), which are urgent problems that need to be addressed. In this study, a catalyst (P100–Fe–N/C) with homogeneous P–tuned FeN2 binuclear sites (N2PFe-FePN2) was successfully synthesised, demonstrating satisfactory performance in the ECR to CO. P100–Fe–N/C attains a peak FECO of 98.01% and a normalized TOF of 664.7 h-1 at −0.7 VRHE, surpassing the performance of the Fe binuclear catalyst without P and single-atoms catalysts. In the MEA cell, a FECO exceeding 90% can still be achieved. Density functional theory analysis indicates that the asymmetric coordination configuration induced by the incorporation of P facilitates a reduction in the system’s energy. The modulation of P results in the d-band centre of the catalyst being positioned closer to the Fermi level, which facilitates the interaction of the catalyst with CO2, allowing more electrons to be injected into the CO2 molecule at the Fe binuclear sites and inhibiting the HER. The P–tuned FeN2 binuclear sites effectively lower the *CO desorption barrier.