Boron-doped carbon nanospheres for efficient and stable electrochemical nitrogen reduction

Electrochemical reduction of dinitrogen (N 2 ) to ammonia (NH 3 ) at the ambient condition is a promising alternative to the traditional Haber-Bosch process due its energy-saving and eco-friendly natures. However, the extremely stable N N triple-bonds in N 2 molecules and the competitive hydrogen evolution reaction (HER) have been regarded as the two essential issues in the electrocatalytic nitrogen reduction reaction (eNRR), making the simultaneous achievement of a high NH 3 yield rate and a satisfactory Faradaic efficiency (FE) very difficult. To address this issue, we herein report a metal-free electrocatalyst, the boron-doped carbon nanosphere, to effectively activate the N N triple-bonds and suppress the HER during the eNRR process. In this protocol, the B–C configurations can be easily tailored by simply changing the boron precursor amount, and the one that is ( i.e. , BC 3 ) beneficial to the enhancement of eNRR can achieve the maximum relative content of ∼43% in the optimum sample. Under this boron-doping amount, the material simultaneously delivers a high NH 3 yield of 33.8 μg h −1 mg −1 cat and a high FE of 39.2% at −0.7 V vs. reversible hydrogen electrode, accompanied with a superior stability for a continuous eNRR. This study thus offers an efficient, stable, and low-cost carbon-based catalyst for eNRR. Boron-doped carbon nanospheres were reported as electrocatalysts to activate the N N triple-bonds and suppress the HER during the eNRR process. Significantly, the B–C configurations can be easily regulated by changing the boron precursor adding amount during materials fabrication. The B–C configuration that is most desirable to improve the eNRR performance ( i.e. , BC 3 ) can achieve the maximum relative content of ∼43% in the material, resulting in a simultaneous and significant enhancement in both ammonian yield rate (33.8 μg h −1 mg −1 cat ) and Faradaic efficiency (39.2% at −0.7 V vs. reversible hydrogen electrode).