WOx nanoparticles coupled with nitrogen-doped porous carbon toward electrocatalytic N2 reduction

Abstract

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 NN 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 NN 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.