Targeted-tuning competitive acidic CO2RR via metalloid antagonism sites

Abstract

To mitigate the high separation costs associated with conventional neutral/alkaline electrocatalysis for CO₂ reduction reactions (CO₂RR), acidic CO₂RR offers economic advantages and improved efficiency in CO₂ utilization. However, it typically involves the cleavage of M−H bonds at a relatively negative potential, leading to the predominant formation of H₂ and poor HCOOH selectivity. Herein, we develop a facile solid-phase thermal diffusion approach to controllably synthesize a novel metalloid-metal single atom alloys (m-SAAs) electrocatalyst Te₁Bi with unique metalloid antagonistic sites, thus enabling high-efficient acidic CO₂-to-HCOOH conversion. Electrochemical test and operando synchrotron radiation multi-techniques (SRMS) characterization reveal that metalloid Te sites bring steric hindrance effect and blocks *H coupling. Furthermore, it actively adsorbs OH⁻ species as a proton source, allowing for effective separation of protons and electrons in space. Thus, leading to enhanced hydrogenation in acidic CO₂RR to produce HCOOH. The flow cell test results demonstrate that the carefully designed Te₁Bi catalyst exhibits a milder reaction potential, along with higher HCOOH Faraday efficiency (∼94.5 %) and single-pass carbon efficiency (SPCE, ∼40 %) in acidic media. This work significantly expands the family of SAAs and offers a novel perspective to analyze the regulation of competitive reactions through site-specific modifications for industrial acidic CO₂RR.