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 N₂ and accept lone electron pairs from N₂ 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 WO₂ phase to the WO₃ phase. WO_x/NPC-700 °C with WO₂ NPs anchored on the surfaces of NPC via W-N bonding could deliver a high NH₃ 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.