Preparation of Sulfur and Nitrogen Co-doped Carbon-Based Porous Nanomaterials for Efficient Electrocatalytic N 2 Reduction

Electrochemical nitrogen fixation represents a new strategy for low-cost fertilizer production because it can be carried out under mild conditions, but the selection of high-stability and high-activity electrocatalysts is a major challenge. In this work, nano-/mesoporous sulfur and nitrogen co-doped carbon as a nitrogen fixation catalyst was obtained by calcining sulfur-doped ZIF-8 at high temperature. The structures of the catalysts were characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy. The catalysts presented a highly disordered three-dimensional porous carbon structure. The formation of an appropriate amount of S 2− , S-O, nitrogen carbide, nitrogen oxide, and pyridinic nitrogen in the catalysts significantly promoted an electrochemical nitrogen reduction reaction (NRR). In 0.1 mol L −1 KOH, the S/N-C-11 catalyst showed a maximum ammonia production rate of 6.9396 μmol cm −2 h −1 and an optimal Faradaic efficiency of 22.74% at − 0.4 V versus a reversible hydrogen electrode under ambient conditions. These results suggest that porous carbon deliberately doped with select heteroatoms may serve as effective catalysts towards electrochemical NRR.