Copper cluster regulated by N, B atoms for enhanced CO2 electroreduction to formate

[Display omitted] •Cu clusters with the diameter of ∼1.0 nm was fabricated and coordinated with B, N atoms in porous carbon matrix.•The catalyst showed stable 70 % FE under 20.8 mA cm−2 during 12 h testing in CO2RR to formate.•The overall catalytic performance of Cu/BN-C was superior to other Cu-based catalysts.•DFT revealed the synergy between Cu clusters and B, N by enhancing the charge density of Cu.•This research highlighted the importance of synergistic effects of Cu size effect and heteroatoms coordination. Electrochemical CO2 conversion into formate by intermittent renewable electricity, presents a captivating prospect for both the storage of renewable electrical energy and the utilization of emitted CO2. Typically, Cu-based catalysts in CO2 reduction reactions favor the production of CO and other by-products. However, we have shifted this selectivity by incorporating B, N co-doped carbon (BNC) in the fabrication of Cu clusters. These Cu clusters are regulated with B, N atoms in a porous carbon matrix (Cu/BN-C), and Zn2+ ions were added to achieve Cu clusters with the diameter size of ∼1.0 nm. The obtained Cu/BN-C possesses a significantly improved catalytic performance in CO2 reduction to formate with a Faradaic efficiency (FE) of up to 70 % and partial current density (jformate) surpassing 20.8 mA cm−2 at −1.0 V vs RHE. The high FE and jformate are maintained over a 12-hour. The overall catalytic performance of Cu/BN-C outperforms those of the other investigated catalysts. Based on the density functional theory (DFT) calculation, the exceptional catalytic behavior is attributed to the synergistic effect between Cu clusters and N, B atoms by modulating the electronic structure and enhancing the charge transfer properties, which promoted a preferential adsorption of HCOO* over COOH*, favoring formate formation.