Computational evaluation of CO2 conversion into formic acid via a novel adsorption mechanism on metal-free B4C12

Abstract

The electrochemical reduction of CO₂ (CO2RR) to formic acid (HCOOH) is a promising approach to harness renewable energy for the production of value-added chemicals and contribute to carbon cycling. The search for cost-effective and efficient metal-free electrocatalysts is critical for realizing industrial applications. However, limited literature is available on this topic, primarily because the significant challenge of efficiently activating inert CO₂ remains unresolved. In this study, we have designed and applied a novel boron carbide (B₄C₁₂) monolayered cage as an electrocatalyst for CO2RR to produce HCOOH. B₄C₁₂ exhibits exceptional electronic, dynamic, and thermodynamic stability. Through comprehensive density functional theory computations, we have observed that B₄C₁₂ rapidly and stably adsorbs CO₂ in a unique η³(O, C, O)-CO₂ configuration, resulting in excellent CO2RR activity with a low limiting potential (–0.38 V) and suppressed hydrogen evolution reaction. Our mechanistic investigations reveal that B₄C₁₂ donates electrons to facilitate the bending of CO₂, anchoring it onto the curved surface effectively. Additionally, the C atom in the η³(O, C, O)-CO₂ configuration attracts H⁺ + e⁻ pairs through its active p electron, leading to the observed low limiting potential. This study not only successfully designs a novel class of metal-free electrocatalysts but also provides a promising strategy for advancing CO2RR research in the future.