ZIF-67-Derived Cobalt/Nitrogen-Doped Carbon Composites for Efficient Electrocatalytic N2 Reduction

Electrochemical N-2 reduction (ENR) provides a potential approach for NH3 synthesis. To facilitate ENR, the development of naturally abundant, cheap, and effective electrocatalysts is critically important. Herein, we report Co/nitrogen-doped carbon composites comprising a large number of single Co sites for efficient N-2 electrofixation at ambient conditions. The N configurations and Co species in the catalysts are readily tunable by controlling the calcination temperatures. Such low-cost catalysts enhanced electrochemical reduction of dinitrogen to ammonia, yielding a maximum ammonia production rate of about 5.1 mu g(NH3) h(-1) mg(cat).(-1) at -0.4 V (vs. the reversible hydrogen electrode, RHE) and a Faradaic efficiency of up to 10.1% at -0.1 V (vs. RHE) in 0.1 M KOH electrolyte. We inferred that single Co atoms together with pyrrolic N may be major active sites for N-2 activation. This work would provide an easy and alternative method for the synthesis of transition-metal catalysts for ENR.