N-doped graphene supported WxC composite material as an efficient non-noble metal electrocatalyst for hydrogen evolution reaction

Abstract

Tungsten carbides materials exhibit highly efficient activity for hydrogen evolution reaction (HER) as promising non-precious electrocatalysts. Herein, a N-doped graphene (NG) supported tungsten carbides composite material (WxC/NG-10, x=1, 2, x is stoichiometric number of W, 10 is the mole quantity of tungsten in the precursors, mmol) was directly synthesized with a simple method by two-step calcining the mixture of sodium tungstate dihydrate (Na2WO4·2H2O), dicyandiamide (DCDA) and glucose anhydrous (GA), which was characterized by HRTEM, FE-SEM, XRD, XPS, EDX, BET and Raman, and estimated the electrocatalytic activity by the LSV, Tafel curves, and electrochemical impedance spectrum (EIS). The investigations indicate that WxC/NG-10, as an electrocatalyst for HER, achieves a lower overpotential of only 77.82mV at the current density of 10mAcm−2 and a Tafel slope of 45.95mVdec−1 in 0.5molL−1H2SO4 aqueous. Additionally, the WxC/NG-10 has also possessed an electrocatalytic oxygen evolution reaction (OER) activity in 1.0molL−1 KOH aqueous with a lower overpotential of 467.6mV and a Tafel slope of 36.2mVdec−1. And after 10000 cycles the electrocatalytic active of WxC/NG-10 decrease 24.63% and 19.35% for HER and OER, respectively. The modification of WxC has improved the activity of NG materials in electrocatalytic applications.