Hierarchical porous CuFe-MOF nanostructures as dual electrocatalyst for hydrogen evolution reaction and nitrate reduction reaction

The potential to eliminate nitrate pollution in waste effluents by electrochemically reducing nitrate to ammonia has sparked global interest in developing highly active electrocatalysts for the nitrate reduction reaction (NO₃RR). Metal-organic frameworks (MOFs) have emerged as a promising candidate for creating the next-generation NO₃RR electrocatalysts due to their abundant active metal sites, electrical conductivity, and well-organized porous structure. In this context, we report the synthesis and applications of a unique bimetallic MOF, i.e., CuFe(x:y)MOF, as an efficient dual electrocatalyst for NO₃RR and hydrogen evolution reaction (HER). We have carefully adjusted the Cu to Fe ratio in CuFe(x:y)MOF to achieve the best possible result. The CuFe(1:2)MOF, with its distinct features, showed excellent NO₃RR with a high ammonia yield of 5.08 mmol/(h⋅cm²) and 87 % faradaic efficiency. Moreover, the material demonstrated catalytic activity for the hydrogen evolution reaction, exhibiting an overpotential of 175 mV and a low Tafel slope of 295 mV/dec under optimized conditions. Further, chronoamperometry studies revealed that the catalyst remained stable for 24 h. These findings underscore the potential of the CuFe(x:y)MOF as an efficient dual electrocatalyst and a significant step forward in developing next-generation catalysts.