Selective electroreduction of dinitrogen to ammonia on a molecular iron phthalocyanine/O-MWCNT catalyst under ambient...

Effective catalysts with sufficient activity and selectivity are essential for the nitrogen reduction reaction (NRR). Many fruitful NRR electrocatalysts have been investigated with regard to NH₃ production under ambient conditions in recent years. However, well-defined and modifiable molecular catalysts have rarely been reported for the NRR to date. Here, molecular FePc was grafted on an O-MWCNT surface as a NRR electrocatalyst to improve its recyclability. This catalyst displayed high electrocatalytic ability and selectivity, giving a large NH₃ yield of 36 μg h^-1 mg^-1 cat., a FE of 9.73% and a turnover number (TON) of 12.56 after 2 h of electrocatalytic reaction in an acidic electrolyte, superior to most of the reported materials. DFT calculations indicated that the NRR preferentially proceeded along the alternate pathway, the activation of N₂ to produce N₂H* is the rate-limiting step with a ΔG value of 1.79 eV. Conclusively, we report FePc/O-MWCNT as a low-cost, high-efficiency NRR catalyst that also offers a valuable reference for molecular electrocatalyst research in electrochemical nitrogen reduction.