Synthesis Of Ru/Metal Oxide Based Materials For Electrocatalytic Hydrogen Evolution

Developing green energy sources is an effective approache to alleviate environmental pollution and energy shortage.As an efficient and clean energy carrier,H₂ provides a high combustion heat.Elelctrocatalytic hydrogen evolution reaction（HER）is an economical and green approach with sustainable and non-polluting characteristics.The sluggish kinetics is an obstacle for hydrogen evolution reaction.It remains an challenge to explore the efficient catalysts with high efficiency and good activity.To date,researchers have made effort to mediate transition metal oxide-based materials for water reduction reaction owing to low-cost and high stability.Transition metal oxides exhibit the low activity due to their poor conductivity and could catalyze hydrogen evolution reaction in both acidic and alkaline electrolytes.As we known,the strength of ruthenium-hydrogen bond is similar to that of platinum-hydrogen bond and Ruthenium is much cheaper than platinum.In this paper,coupling of Ru/metal oxides-based materials with N-doped carbon sheets were achieved.The catalytic performance was improved by the synergistic effect by Ru nanoparticles,transition metal oxides,and N-doped carbon nanosheets.（1）The catalytic activity is association with the composition and coordinated structure of samples.Fe₂O₃ nanosheets were obtained by simple hydrothermal method.Subsequently,Ru/Fe₃O₄-Fe₃C/NC was obtained by high temperature pyrolysis process.In 1.0 mol/L KOH,Ru/Fe₃O₄-Fe₃C/NC required an overpotential of 148 m V to reach10 m A/cm² for hydrogen evolution reaction.In 0.5 mol/L H₂SO₄,the overpotential for Ru/Fe₃O₄-Fe₃C/NC at the same current is 141 m V.I-t testing indicated that Ru/Fe₃O₄-Fe₃C/NC catalysts maintained long-term stability.The high catalytic activity for Ru/Fe₃O₄-Fe₃C/NC could attribute to the well-dispersion of Ru nanoparticles,Fe₃O₄-Fe₃C heterostructures,and N-doped carbon.（2）WO₃ nanosheets were obtained by a simple hydrothermal method.Ru/WO₃-W₂N/NC was prepared by calcination a mixture of WO₃,dopamine hydrochloride,Tris（hydroxymethyl aminomethane）,and Ru Cl₃·x H₂O.The electrochemical activity for Ru/WO₃-W₂N/NC were tested in 1.0 mol/L KOH and 0.5mol/L H₂SO₄ electrolytes,respectively.To reach a current density of 10 m A/cm²,the overpotentials for Ru/WO₃-W₂N/NC were 110 m V and 64 m V in acidic and alkaline media,respectively,which was lower than that of WO₃/NC.For comparison,the catalytic activity for samples was also tested by changing the synthetic parameters,including Ru concentration and pyrolysis temperature.The excellent activity for Ru/WO₃-W₂N/NC could be related to the synergistic effect of Ru nanoparticles,WO₃-W₂N,and N-doped carbon nanosheets.（3）h-MoO₃microrods were obtained by a simple hydrothermal method.Ru/MoO₂/NC was prepared by pyrolysis of a mixture of h-MoO₃,dopamine hydrochloride,Tris,and Ru Cl₃·x H₂O.When the current density was 10 m A/cm²,the required overpotentials were 89 m V and 55 m V in acidic and alkaline media,respectively.Ru/MoO₂/NC could maintain long-term stability by continuous i-t tests.The good activity for Ru/MoO₂/NC may originate from the strong interaction of Ru nanoparticles,MoO₂,and N-doped carbon nanosheets.