Copper Single Atoms Anchored in Porous Nitrogen-Doped\nCarbon as Efficient pH-Universal Catalysts for the Nitrogen Reduction\nReaction

Abstract

Artificial\nnitrogen fixation through the nitrogen reduction reaction\n(NRR) under ambient conditions is a potentially promising alternative\nto the traditional energy-intensive Haber–Bosch process. For\nthis purpose, efficient catalysts are urgently required to activate\nand reduce nitrogen into ammonia. Herein, by the combination of experiments\nand first-principles calculations, we demonstrate that copper single\natoms, attached in a porous nitrogen-doped carbon network, provide\nhighly efficient NRR electrocatalysis, which compares favorably with\nthose previously reported. Benefiting from the high density of exposed\nactive sites and the high level of porosity, the Cu SAC exhibits high\nNH₃ yield rate and Faradaic efficiency (FE), specifically\n∼53.3 μg_NH₃ h^–1 mg_cat^–1 and 13.8% under 0.1 M KOH,\n∼49.3 μg_NH₃ h^–1 mg_cat^–1 and 11.7% under 0.1 M HCl,\nmaking them truly pH-universal. They also show good stability with\nlittle current attenuation over 12 h of continuous operation. Cu–N₂ coordination is identified as the efficient active sites\nfor the NRR catalysis.