Towards efficient CO2RR electrocatalysts: a study of structure and properties of M-N-E active moieties embedded in a biphenylene framework (M = Mn, Fe, Co, Ni, Cu; E = C, B)

In the context of C-based 2D nanomaterials, the stereoelectronic situation of putative M-N-E active moieties (M = Mn, Fe, Co, Ni, Cu; E = C, B) embedded in biphenylene (BPN) monolayer frameworks and their electrocatalytic performance in the CO2 greenhouse gas reduction reaction (CO2RR) are studied in silico by means of dispersion-corrected DFT, AIMD, CI-NEB, and COHP quantum chemical calculations. It is found that the M-N-B-modified BPN framework possesses excellent thermal and electrochemical stability, capability for effective localization of the solid-state electron-energy bands originated from the d-AOs of M atoms, and enhanced affinity towards the CO2RR intermediates, which reduces the Gibbs free energy and facilitates the CO2RR. The Fe-N-B active moiety exhibits excellent adsorption performance for CO2RR intermediates through secondary bonding interactions, as well as selectivity towards CH3OH and CH4 high-value production revealing the limiting potential UL = 0.64 V in both cases, while the Co-N-C moiety reveals the optimal UL of 0.6 V favoring the CO2RR both kinetically and thermodynamically. Importantly, the M-N-E active moieties prevent the CO2RR-competing hydrogen evolution reaction (HER). Overall, M-N-E-modified BPN frameworks are promising for the design and synthesis of novel efficient CO2RR electrocatalysts.