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

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 (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 (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.