Integration of B-doped Co nanoclusters within Cu metal–organic frameworks for highly efficient electrocatalytic nitrate reduction

The increasing nitrate pollution from agriculture and industry requires sustainable solutions. The electrocatalytic nitrate reduction reaction (e-NO₃⁻RR) has emerged as a dual-benefit strategy for environmental remediation and NH₃ synthesis. Despite the cluster catalysts combining the advantages of single atoms and multi-site nanocatalysts, metal aggregation can limit performance. We showed a synergistic catalyst design by embedding B-doped Co nanoclusters in a conductive Cu-HHTP MOF, resulting in CoB@Cu-HHTP with outstanding e-NO₃⁻RR performance. It achieves 99% faradaic efficiency (FE) and an NH₃ production rate of 2797 μmol h⁻¹ mg_cat⁻¹ (559 μmol h⁻¹ cm⁻²), which is 3.3 times higher than that of pristine Cu-HHTP. In situ Raman spectroscopy and theoretical calculations indicate that the loading of CoB nanoclusters accelerates the generation of NH₃. Specifically, the introduction of Co reduces the energy barrier for the adsorption of NO₃⁻, promoting the activation of NO₃⁻ and favoring the formation of NO₂⁻. Concurrently, B doping lowers the energy barrier for the conversion of *NO to *NOH, expediting the transformation from NO₂⁻ to NH₃. This method underscores the importance of integrating metal nanoclusters into porous MOFs for designing high-performance synergistic electrocatalysts for the e-NO₃⁻RR.