Study On Synthesis And Performance Of Noble Metal Electrocatalysts In Hydrogen Energy Conversion

Noble metal electrocatalysts occupy a very important position in hydrogen energy conversion.Improving the performance of noble metal electrocatalysts and reducing the usage of noble metals are critical to promoting the development of hydrogen energy economy.The performance of noble metal electrocatalysts is related to their morphology,structure,composition,size etc.In this paper,Ru@Pt_0.24Ru nanoflowers,PtRh/NiO ultrafine nanorods?NRs?,and PdNi nanowires?NWs?were synthesized by controlling the morphology,structure,and composition of noble metal electrocatalysts precisely under appropriate reaction systems.The effect of various reaction conditions on their morphology,structure and performance were discussed in detail.The main results are as follows:?1?Core shell structured Ru@Pt_0.24Ru nanoflowers electrocatalyst was synthesized by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol.The average diameter of the Ru@Pt_0.24Ru was 16.5±4.0 nm.The electrocatalyst was characterized by high resolution transmission electron microscopy,inductively coupled plasma atomic emission spectroscopy,and X-ray photoelectron spectroscopy.The performance of the electrocatalyst toward alkaline hydrogen evolution reaction was tested in 0.1 M KOH aqueous solution.The overpotential of Ru@Pt_0.24Ru/C is 22 mV at 10 mA·cm^-2.After durability test,the overpotential is increased to 30 mV at 10 mA·cm^-2.Our electrocatalyst is much better than commercial Pt/C with an initial overpotential of 60 mV at 10 mA·cm^-2 and a final overpotential of 85 mV at 10 mA·cm^-22 after durability test.The significantly improved electrochemical activity may be derived from the electronic and geometric effects of the electrocatalyst.The improvement of durability may be due to the stability of the nanoflowers morphology.?2?Under oleylamine system,the ultrafine nanorods with the interface amorphous NiO and polycrystalline PtRh alloy?PtRh/NiO NRs?were synthesized by a one-pot wet chemical method.The average diameter of the PtRh/NiO NRs was 1.9±0.8 nm,length was 18.7±9.0nm.The performance of the electrocatalyst toward alkaline hydrogen evolution reaction was tested in 1.0 M KOH aqueous solution.The overpotential of PtRh/NiO NRs/C is 8.7 mV at 10mA·cm^-2,the slope of Tafel is 30 mV·dec^-1,and the mass activity is 6.5 A·mg_Pt^-1?@0.04 V?,which are better than those of commercial Pt/C(58.0 mV,115 mV·dec^-1,0.41 A·mg_Pt^-1).The PtRh/NiO NRs also have excellent electrochemical stability.The significantly improved electrochemical activity is due to the synergy of different components at the interface,and the improvement in durability comes from the stability of the one-dimensional ultrafine nanorod structure.?3?Under the oleylamine system,a series of Pd-based nanowires electrocatalysts were synthesized?PdNi,PdCo,PdFe and PdLa?with the guidance of surfactants CTAB,and investigated their alkaline oxygen reduction performance.We purified the surface of the PdNi NWs by acid and heat treatment to expose the masked active sites and improve the PdNi NWs ORR catalytic activity.The half-wave potential of PdNi NWs in 0.1 M KOH aqueous solution is 0.902 V,and the mass activity is 0.607 A·mg_Pd^-1?0.9 V vs.RHE?,which are both better than those of commercial Pt/C(0.865 V,0.196 A·mg_Pt^-1).Due to the stability of the nanowires structure,the stability of PdNi NWs is better than commercial Pt/C.