Abstract
The generation of pure H-2 from a neutral electrolyte solution represents a transformative route with low cost and environmentally friendly nature. However, the complex kinetics of hydrogen evolution reaction (HER) via water electrolysis make its practical application to be difficult. Herein, we have reported Ru-doping-induced formation of VS4 nanostructures with a rich S vacancy for neutral HER in a 0.2 M phosphate buffer solution. The Ru-doped VS4 demands an overpotential value of 160 mV at 10 mA/cm(2) current density with a lower catalyst loading of 0.1 mg/cm(2), while pristine VS4 demands a 374 mV overpotential with the same mass loading. 60 hours of chronoamperometric study reveals the excellent stability of Ru-doped VS4 materials, which is the highest amount of time ever reported for neutral HER The marginal degradation of a catalyst under a long-term stability study was confirmed through inductively coupled plasma mass spectrometry (ICP-MS) analysis. The introduction of Ru to the VS4 lattice leads to a 4.3S-fold increase in the turnover-frequency values compared to those of bare VS4 nanostructures. The higher HER activity of S-vacancy-enriched VS4 materials is thought to originate through effective water adsorption in S vacancy and Ru3+ sites followed by the dissociation of a H2O molecule, and S-2(2-) efficiently converts H-ad to H-2. Also, post-HER characterization reveals that the transformation of some Ru3+ to Ru-0 additionally favored the HER by providing a better H adsorption site under a static cathodic potential.