Structurally reversible Bi0/Bi2O2CO3 functional layer engineering for durable electrochemical CO2 reduction to formate

A reversible Bi 0 /Bi 2 O 2 CO 3 functional layer was constructed on CuBi 2 O 4 via in situ solvothermal reconstruction. • The Bi/BOC layer suppresses metal dissolution and irreversible catalyst reconstruction during CO 2 electroreduction. • The Bi/BOC heterointerface optimizes Bi electronic states and lowers the energy barrier for *OCHO formation. • Bi/BOC@CBO achieves high stability and Faradaic efficiency for formate production. Achieving high activity and exceptional operational stability remains challenging for electrocatalytic CO 2 reduction, primarily due to metal dissolution and structural reconstruction of catalysts under CO 2 RR conditions. Herein, we developed an in situ solvothermal strategy to preconstruct a structurally reversible Bi 0 /Bi 2 O 2 CO 3 (Bi/BOC) functional layer on CuBi 2 O 4 , transforming otherwise uncontrolled reconstruction into a regulated interfacial structural response. The resulting Bi/BOC functional layer enhances catalyst stability by combining physical surface protection against metal dissolution with reversible Bi 0 ↔ Bi 2 O 2 CO 3 structural evolution, thereby markedly suppressing uncontrolled dissolution and reconstruction during prolonged CO 2 electroreduction. Meanwhile, the Bi/BOC heterointerface modulates the electronic structure of Bi sites and interfacial proton transfer, lowering the energy barrier for *OCHO formation and enhancing CO 2 -to-formate conversion. Consequently, the Bi/BOC@CBO catalyst achieves a formate Faradaic efficiency of 96.9% with a production rate of 3.64 mmol·h −1 ·cm −2 at 200 mA·cm −2 , while maintaining 94.6% FE over 90 h. This work establishes structurally reversible functional-layer engineering as an effective approach to regulate catalyst reconstruction and balance catalytic performance with structural stability in multimetallic electrocatalysts for CO 2 reduction. Download: Download high-res image (220KB) Download: Download full-size image