Oxygen-vacancy-rich cerium oxide integrated with Cu dual active sites for efficient electrocatalytic nitrate...

The electrocatalytic nitrate (NO₃^-) reduction reaction (NO₃RR) presents a sustainable and promising avenue for simultaneous ammonia (NH₃) synthesis and wastewater remediation. However, conventional copper (Cu)-based catalysts are severely bottlenecked by sluggish water dissociation kinetics and a consequent deficiency in active hydrogen (^⁎H) supply. Herein, we construct an interfacial dual-site catalyst consisting of oxygen-vacancy-rich cerium oxide nanoclusters anchored on a copper foam substrate (CeO_x@Cu). Specifically, the oxygen vacancies on CeO_x promote water dissociation to generate ^⁎H, which subsequently spills over to adjacent Cu sites to accelerate the nitrate hydrogenation step. This synergistic relay mechanism is comprehensively validated by density functional theory (DFT) computations and operando Fourier-transform infrared (FTIR) spectroscopy. Consequently, the as-prepared CeO_x@Cu catalyst exhibits a balanced catalytic performance under neutral conditions, concurrently achieving a Faradaic efficiency (FE) of 94.6% and a corresponding NH₃ yield rate of 404.08 μmol h^-1 cm^-2 (corresponding to 6.88 mg h^-1 cm^-2) at a low potential of -0.5 V versus the reversible hydrogen electrode (vs. RHE). Furthermore, the practical viability of the catalyst is demonstrated in an assembled zinc-nitrate battery, which delivers a peak power density of 5.85 mW cm^-2 alongside robust durability. This study provides valuable insights into coordinating vacancy engineering and spillover kinetics for the rational design of high-efficiency dual-site electrocatalysts.