Preparation And Electrochemical Performance Of Ru-based Nanocomposite

Ru is one of the most promising catalysts for replacing precious metal Pt for hydrogen production by electrolysis of water.Ru nanoclusters exhibit excellent catalytic activity due to their unique quantum size effect and low coordination atomic level catalytic active sites.However,the high free energy of its surface makes it easy to agglomerate during preparation and electrochemical testing.The special porous structure and large specific surface area of porous carbon（PC）provide abundant anchor points for nanoclusters.In this thesis,a series of Ru/RuPt cluster nanocomposites were prepared using porous carbon as a carrier.1.Ultrasmall Ru nanoclusters（～1.30 nm）/Na⁺,K⁺-modified porous carbon composites（Ru/Na⁺,K⁺-PC）were prepared by hydrothermal synthesis and annealing treatment.In a 1 M KOH water/seawater solution,Ru/Na⁺,K⁺-PC can achieve a current density of 10 mA cm^-2with only 7 mV/15 mV（commercial Pt/C:40 mV/55mV）.The mass activity（MA）/turnover frequency（TOF）at 100 mV overpotential can be as high as 15.7 A mg _Ru^-1/8.21 s^-1,which is 5.81/5.74 times that of Pt/C.Ru/Na⁺,K⁺-PC showed a negligible decrease in activity in the durability test of 20,000 cycles of CV（cyclic voltammetry）and 200 hours of chronopotentiometric,far superior to commercial Pt/C.Density functional theory calculations indicate that the presence of Na and K ions can effectively reduce the energy barrier of H-OH bond breakage,which is beneficial to the Volmer step.More importantly,both Ru/Na⁺,K⁺-PC can efficiently utilize solar energy to produce hydrogen in alkaline water/seawater electrolyzers.2.Using H₂PtCl₆·6H₂O and RuCl₃·xH₂O as metal precursors,RuPt cluster nanocomposites with different proportions were prepared by one pot method.Ru in RuPt/PC nanocomposites is conducive to the dissociation of hydrated protons during hydrogen precipitation.Pt can effectively regulate the adsorption of protons,and synergistically effectively promote（hydrogen evolution reaction）HER activity.In alkaline water/seawater,Ru_0.85Pt_0.15/PC requires only 12 and 25 mV to achieve a current density of 10 mA cm^-2,which is far superior to commercial Pt/C.At the same time,Ru_0.85Pt_0.15/PC can keep accelerate CV testing in alkaline water/seawater for up to 50,000/30,000 cycles.In addition,the catalytic activity of Ru_0.85Pt_0.15/PC in acidic electrolytes can also be comparable to Pt/C.