Bifunctional Amorphous Phosphate Layer Simultaneously Boosts Proton Transfer and Stabilizes Zn Active Sites for Efficient CO2RR

Zinc (Zn) is an attractive electrocatalyst for converting CO 2 to carbon monoxide (CO) via the carbon dioxide reduction reaction (CO 2 RR), but its application is limited by poor selectivity and stability. In contrast to conventional crystalline modifiers or bulk buffers, we report a bifunctional strategy using an amorphous phosphate layer to simultaneously enhance proton transfer and stabilize Zn active sites. Amorphous phosphate-modified zinc nanoflakes (Zn-HPO 4 NF) were synthesized through a simple two-step method. At −1.3 V versus RHE, the Zn-HPO 4 catalyst delivers a CO Faradaic efficiency (FE CO ) of 86.4%. The catalyst exhibits exceptional durability at −1.4V versus RHE, sustaining a stable current of ~17 mA over 20 h with an average FE CO exceeding 80% and negligible current decay, significantly outperforming pure Zn. In situ spectroscopy and operando electrochemical impedance spectroscopy reveal that amorphous hydrogen phosphate (HPO 4 2- ) modification promotes the adsorption of key intermediates (*CO 3 2- and *COOH), facilitates efficient proton transfer through the establishment of an ordered hydrogen-bonding network (consistent with the Grotthuss mechanism), and stabilizes Zn active sites by acting as a buffer to regulate the local pH environment. These effects collectively enhance the stability and catalytic performance of the catalyst during CO 2 RR. Graphical Bifunctional amorphous phosphate layer simultaneously enhances proton transfer and stabilizes Zn active sites for efficient CO 2 RR. An engineered Zn-HPO 4 overlayer enhances *COOH/*CO 3 2- stabilization and water dissociation while suppressing parasitic hydrogen evolution reactions and Zn dissolution. This synergistic microenvironment regulation delivers 86.4% CO Faradaic efficiency with robust 20 h stability, markedly outperforming pristine Zn catalysts.