WO x nanoparticles coupled with nitrogen-doped porous carbon toward electrocatalytic N 2 reduction.

The electrocatalytic nitrogen reduction reaction (eNRR) is a sustainable and green alternative to the traditional Haber-Bosch process. However, the chemical inertness of nitrogen gas and the competitive hydrogen evolution reaction significantly limit the catalytic performance of eNRR. Although tungsten oxide-based eNRR catalysts could donate unpaired electrons to the antibonding orbitals of N 2 and accept lone electron pairs from N 2 to dissociate NN triple bonds, the low electrical conductivity and the influence of the variable valence of W still affect the catalytic activity. Herein, a high-performance eNRR catalyst WO x nanoparticle/nitrogen-doped porous carbon (WO x /NPC) was prepared by a one-step thermal pyrolysis method. The results reveal that WO x gradually changes from the dominant WO 2 phase to the WO 3 phase. WO x /NPC-700 °C with WO 2 NPs anchored on the surfaces of NPC via W-N bonding could deliver a high NH 3 yield of 46.8 μg h -1 mg -1 and a high faradaic efficiency (FE) of 10.2%. The edge W atomic site on WO x /NPC is demonstrated to be the active center which could activate a stable NN triple bond with an electron-donating ability. Benefiting from the covalent interaction between the WO x nanoparticles and NPC, WO x /NPC also shows high electrocatalytic stability.