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

Abstract

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.