Can Metal–Nitrogen–Carbon Single-Atom Catalysts Boost the Electroreduction of Carbon Monoxide?

Abstract

Metal−nitrogen−carbon single-atom catalysts (SACs) have exhibited substantial potential for CO 2 electroreduction. Unfortunately, the SACs generally cannot generate chemicals other than CO, while deep reduction products are more appealing because of their higher market potential, and the origin of governing CO reduction (COR) remains elusive. Here, by using constant-potential/hybrid-solvent modeling and revisiting Cu catalysts, we show that the Langmuir−Hinshelwood mechanism is of importance for *CO hydrogenation, and the pristine SACs lack another site to place *H, thus preventing their COR. Then, we propose a regulation strategy to enable COR on the SACs: (I) the metal site has a moderate CO adsorption affinity; (II) the graphene skeleton is doped by a heteroatom to allow *H formation; and (III) the distance between the heteroatom and the metal atom is appropriate to facilitate *H migration. We discover a P-doped Fe−N−C SAC with promising COR reactivity and further extend this model to other SACs. This work provides mechanistic insight into the limiting factors of COR and highlights the rational design of the local structures of active centers in electrocatalysis.

Homonuclear multi-atom catalysts for CO2 electroreduction: a comparison density functional theory study with their single-atom counterparts

“…In the CP simulations, the total energy of intermediates is potential-dependent. Following previous DFT works, 48,49 we neglect the cavitation energy contribution during the VASPsol simulations to avoid numerical instabilities. The electric potentials between the RHE scale and SHE scale can be correlated as U RHE = U SHE + k B T ln (10) pH/ e. The value of pH was set as zero in the energy simulations.…”

Cation-Induced Interfacial Hydrophobic Microenvironment Promotes the C–C Coupling in Electrochemical CO2 Reduction

“…Understanding the structure and dynamic process of H 2 O at the EDL is an extremely significant topic in electrochemistry. − The interfacial water molecules play diverse roles in CO 2 electroreduction. On the one hand, they exhibit a significant stabilizing effect on intermediate species in the CO 2 RR, which could benefit the C 2 selectivity. − However, on the other hand, they serve as the proton donors for the hydrogenation steps, thereby possibly facilitating the deep reduction of CO 2 toward C 1 products and undergoing the side reaction of hydrogen evolution reaction (HER), impeding the generation of C 2 products. − Reducing the activity of water molecules can effectively suppress the HER, enhancing the selectivity of C 2 products …”

Deciphering Mesopore-Augmented CO2 Electroreduction over Atomically Dispersed Fe–N-doped Carbon Catalysts

“…), offer a cost-effective and highly efficient solution for converting CO 2 into CO. − The atomically dispersed metal–nitrogen moieties (M–N x ) on the surface of M–N–C catalysts have been identified as active sites responsible for the CO 2 -to-CO conversion through a combination of various spectroscopic techniques and computational analyses. , To improve the catalytic performance, significant efforts have been directed toward optimizing the intrinsic activity of M–N x sites. It involves tailoring the coordination structure, such as adjusting the coordination number and configuration, − as well as introducing heteroatoms (e.g., O, F, − S, − P , ) in the vicinity of the active sites. These modifications effectively manipulate the electronic structure of the metal centers, leading to enhanced adsorption or desorption of key intermediates (e.g., *COOH) during CO 2 R, thereby promoting CO production …”