Breaking the CO bridge trap: boron–transition-metal trimer clusters for efficient C–C coupling in CO2 reduction

Abstract

Biatom catalysts (BACs) anchored on N-doped graphene have been highlighted as atom-efficient platforms for CO₂ electroreduction, yet they consistently fail to forge the crucial C–C bond: *CO strongly bridges the two metals, stalling product evolution at the C₁ stage. Here, we break that impasse by introducing hybrid triatomic clusters—a p-block B atom integrated with two transition metals (B-2TM)—embedded in N-doped graphene (B-2TM@NC). First-principles calculations reveal B-2V@NC as a standout: its unique electronic synergy and geometric flexibility create adjacent yet non-blocking adsorption pockets, lowering the C–C coupling barrier and steering the reaction toward multi-carbon (C₂₊) products. We uncover a clear design rule: progressive hydrogenation of C₁ intermediates further reduces the coupling barrier, while the interposed B atom suppresses the notorious bridging-CO trap that plagues conventional BACs. Moreover, the introduction of the B atom effectively modulates the adsorption strength of C-species adsorption, promoting C–C coupling. This work thus provides atomistic insights into multi-carbon formation on bi-metal graphene hosts, transforming a long-standing limitation into a tractable design principle and opening a new avenue for high-value C₂₊ CO₂RR electrocatalysts.