| Electrocatalytic hydrogen evolution reaction and direct methanol fuel cell,as efficient and clean energy conversion systems,are of great significance for solving the reduced energy and environmental pollution.However,the reaction kinetics of the cathode hydrogen evolution reaction（HER）and anode methanol oxidation reaction（MOR）occurred at the electrode interface is slow.Therefore,the development of low-cost,efficient and stable Pt-based precious metal electrocatalyst is the key to achieve their large-scale commercial application.For hydrogen evolution reaction,commercial Pt/C is considered to be the most ideal catalyst becauseΔGH*is close to 0.However,high price,low reserve,as well as poor activity in neutral and alkaline electrolyte severely limit its commercial application.While for methanol oxidation reaction,Pt based nanocrystals encolsed by high-index facets（HIFs）have special advantages over LIFs because high density of low-coordinated atoms in the forms of atomic steps and kinks are favorable for electrocatalytic reactions.However,they are usually suffered from thermodynamically unstable and easy to cause surface restructure due to the high density of atomic steps,ledges,and kinks as well as the high surface energy.On account of this,a series of catalysts with low Pt loading and over a wide p H range have been synthesized with the strategies of structural and component regulation.The performance of Pt Ni nanocrystal encolsed by HIFs toward anode methanol oxidation reaction were greatly enhanced through surface non-metal atom doping strategy.The main results are as follows:To prepare low-cost,efficient and stable Pt-based precious metal electrocatalyst.We have developed a facile method to synthesize ultralow（0.66 wt%）Pt doped Fe Ni alloy nanoparticles（NPs）embedded in porous graphene shells architecture（denoted as Pt-Fe Ni@C）.The resulting Pt-Fe Ni@C catalyst exhibits an efficient specific activity and a small Tafel slope for HER in 0.5 M H2SO4.Meanwhile,it also possessed an excellent stability,maintaining stable at current density of 10 m A cm-2 for 10 h with negligible loss.Especially,the mass activity of the Pt-Fe Ni@C is 63.0 times higher than that of commercial Pt/C catalyst at overpotential of 50 m V.Although the utilization efficiency of the above Pt-based electrocatalyst has been improved and exhibits excellent hydrogen evolution performance in acid electrolytes,it is more advantageous to prepare an electrocatalyst with efficient hydrogen evolution performance in the entire p H range.To solve this problem,we develop an efficient strategy for engineering few-layer Mo S2 catalyst via synergistic carbon nanotube and Pt nanoparticles hybridization with DMF as solvent and reducing agent.The as-prepared Pt-Mo S2/MWCNTs provides an excellent HER electrocatalytic activity with low overpotentials at-10 m A cm-2 over a wide p H range,namely,20 m V in 0.5 M H2SO4,92 m V in 1.0 M phosphate buffer solution,and 75 m V in 1.0 M KOH,respectively.In addition,Pt-Mo S2/MWCNTs deliver the highest mass activity at the overpotential of0.05 V,which is 8.1,2.3,and 26.5 times higher than that of commercial 20 wt%Pt/C in acidic,neutral and alkaline media,respectively.Density functional theory（DFT）calculations revealed that the co-existence of Mo S2 and Pt NPs facilitated the water dissociation reaction and hydrogen generation,thereby enhancing the activity of HER.In recent years,although the MOR activity Pt based nanocrystals encolsed by HIFs have been improved,the surface structure modification of these material was still little.On account of this,we have developed a facile method to modify the surface structure of Pt Ni concave cube（P-Pt Ni CNC）by doping small amount of phosphorus（P）.The P doped Pt Ni CNC with HIFs toward methanol oxidation reaction（MOR）in 0.5 M H2SO4electrolytes is significantly enhanced.Specifically,the as-obtained P-Pt Ni CNC shows high specific and mass activity of 3.85 m A/cm2 and 0.38 A/mg Pt,respectively,which is1.82 and 1.65 times higher than that of Pt Ni CNC,demonstrating that surface engineering of HIFs can effectively enhance the catalytic activity for MOR.Impressively,P-Pt Ni CNC exhibits 8.19 and 1.19 times enhanced specific and mass activity compared with commercial Pt/C.In situ Fourier transform infrared reflection spectroscopy of MOR and oxidation of preadsorbed CO both disclosed that there is much less weak adsorption of CO,whereas the enhanced OH adsorption energy on P-Pt Ni CNC compared with Pt Ni CNC,indicating the strong anti-poisoning ability of P-Pt Ni CNC during methanol electrooxidation,which was demonstrateed by the DFT calculation. |
