MOF‑derived Cu nanosheets with built‑in proton pumps for efficient electrocatalytic nitrate reduction to ammonia

1,4-benzenedicarboxylate-modified Cu nanosheets were synthesized via 2D Cu-BDC MOF precursor and template. • Carboxyl groups on Cu surface enhance H 2 O accumulation for sustained proton supply. • Carboxylate-mediated proton transfer accelerates *NO → *NOH. Tailoring the interfacial microenvironment is essential for regulating proton-coupled electron transfer (PCET) dynamics, key processes governing the electrochemical nitrate reduction reaction (NO 3 − RR) for efficient ammonia (NH 3 ) synthesis. Herein, we design a metal-organic framework-derived Cu nanosheet architecture modified with 1,4-benzenedicarboxylate (BDC@Cu NSs), where BDC molecules serve as built-in “proton pumps” to boost electrocatalytic NO 3 − RR with higher NH 3 production. In situ spectroscopic characterizations, kinetic isotope effect measurements and theoretical calculations demonstrate that the carboxylate groups (−COO − ) of BDC 2− adsorbed on the Cu interface construct an enhanced interfacial hydrogen-bond network for facilitating H 2 O accumulation and dissociation, and capture and transfer protons to nitrogen-containing intermediates via a PCET pathway, which drastically lowers the energy barrier of the potential-determining step (*NO hydrogenation to *NOH), endowing BDC@Cu NSs with a high NH 3 yield, superior Faradaic efficiency, and outstanding operational durability. This study presents a design strategy for engineering electrocatalytic interfacial microenvironments and provides fundamental insight into proton transport within hydrogen-bonded networks at the interface. Download: Download high-res image (136KB) Download: Download full-size image Constructing built-in proton pumps on MOF-derived Cu nanosheets via surface-anchored carboxylate groups enables efficient electrocatalytic nitrate reduction. These groups establish an enhanced interfacial hydrogen-bond network, facilitating H 2 O dissociation and selective proton transfer to *NO intermediates, thereby drastically lowers the energy barrier for ammonia synthesis.