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

Zinc (Zn) is an attractive electrocatalyst for converting CO2 to carbon monoxide (CO) via the carbon dioxide reduction reaction (CO2RR), 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-HPO4 NF) were synthesized through a simple two-step method. At -1.3 V versus RHE, the Zn-HPO4 catalyst delivers a CO Faradaic efficiency (FECO) 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 FECO exceeding 80% and negligible current decay, significantly outperforming pure Zn. In situ spectroscopy and operando electrochemical impedance spectroscopy reveal that amorphous hydrogen phosphate (HPO4 2-) modification promotes the adsorption of key intermediates (*CO3 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 CO2RR.