FeN₄-Embedded Graphene as a Highly Sensitive and Selective Single-Atom Sensor for Reaction Intermediates of...

Exploring effective ways to detect intermediates during the electrochemical CO₂ reduction reaction (CO₂RR) process is pivotal for understanding reaction pathways and underlying mechanisms. Recently, two-dimensional FeN₄-embedded graphene has received increasing attention as a promising catalyst for CO₂RR. Here, by means of density functional theory computations combined with the non-equilibrium Green's function (NEGF) method, we proposed a detection device to evaluate the performance of FeN₄-embedded graphene in intermediates detection during the CO₂RR process. Our results reveal that the four key intermediates, including *COOH, *OCHO, *CHO, and *COH, can be chemisorbed on FeN₄-embedded graphene with high adsorption energies and appropriate charge transfer. The computed current-voltage (I-V) characteristics and transmission spectra suggest that the adsorption of these intermediates induces significant type-dependent changes in currents and transmission coefficients of FeN₄-embedded graphene. Remarkably, the FeN₄-embedded graphene is more sensitive to *COOH and *COH than to *OCHO and *CHO within the entire bias window. Consequently, our theoretical study indicates that the FeN₄-embedded graphene can effectively detect the key intermediates during the CO₂RR process, providing a practical scheme for identifying catalytic reaction pathways and elucidating underlying reaction mechanisms.