Carbon Shell-Mediated Electronic Modulation of NiFe Alloy Electrocatalysts for Efficient CO₂ Electroreduction

Developing highly efficient and stable catalysts for electrochemical carbon dioxide reduction reaction (CO₂RR) remains a significant challenge, particularly for transition metal-based systems that often suffer from excessive hydrogen evolution and catalyst degradation. In this work, we report a carbon-coated NiFe alloy (NiFe@NC) synthesized via a substrate-anchored pyrolysis strategy, in which the carbon shell serves as an electronic modulator and protective layer. DFT calculations and in situ spectroscopic analysis reveal that the carbon layer induces notable electronic reconstruction at the NiFe surface, weakening the back-donation to the anti-bonding orbitals of the *CO intermediate, thus facilitating *CO desorption and improving CO₂RR kinetics. Meanwhile, the carbon layer also suppresses undesired *H adsorption while protecting the catalyst from deactivation under long-term operation. As a result, the NiFe@NC catalyst achieves stable operation at 500 mA cm^-2 for 250 h in a membrane electrode assembly (MEA) system, outperforming most previously reported transition-metal-based catalysts. This work provides a practical strategy for tuning surface electronic structures to overcome the intrinsic limitations of conventional transition metal CO₂RR catalysts.