Precious Metals Supported On Tellurium Nanorods For Synergistic Electrocatalytic Performance

Compared with traditional fossil energy,renewable energy has received more and more attention.Developing direct methanol fuel cells and water electrolysis to produce hydrogen technology is considered to be an effective method to solve energy and environmental problems.Direct methanol fuel cell is an ideal device to solve the future energy crisis,in which methanol oxidation reaction(MOR)and oxygen reduction reaction(ORR)occur on the anode and cathode electrode,respectively.At present,although precious metal Pt and Pd are effective MOR catalysts,the high cost,poor resistance to CO poisoning,and poor stability of these catalysts seriously limit their commercial application in practice.Hydrogen energy is a renewable and efficient clean energy source with high energy density and wide application prospects.Water electrolysis to produce hydrogen is a clean and environmentally friendly way and no pollutants are produced during the production process.It can effectively convert electrical energy produced by intermittent energy sources such as solar energy,wind energy,and tidal energy into chemical energy.Although Pt-based materials are currently recognized as efficient catalysts for hydrogen evolution reaction(HER),the high cost,low reserves,and poor stability of Pt severely limit the widespread application of water electrolysis devices.Therefore,for MOR,synthesizing Pt and Pd-based catalysts with high efficiency and strong stability is significant;for HER,it is essential to develop HER catalysts with excellent catalytic capacity and stability.This paper aims to conduct highly efficient and stable catalyst materials,which were used in MOR and HER.Different noble metals such as Pt,Pd,and Ru were reduced on Te nanorods with uniform size through the simple microwave and hydrothermal reaction.The research content mainly includes the following three parts:(1)Application research of Pt nanoparticles supported on Te nanorods(Pt/Te)catalysts for MOR had been conducted.The Pt nanoparticles were anchored over Te nanorods(Pt/Te)catalysts by the simple ethylene glycol reduction method.Through physical characterization and electrochemical analysis,the Pt/Te catalyst exhibited excellent catalytic activity,anti-CO poisoning,and stability in both 0.5 M H2SO4+1.0 M CH3OH and 1.0 M KOH+1.0 M CH3OH solution.According to the D-band theory and dual-function catalytic mechanism,Te with oxyphilic properties can promote water activation and provide more oxygen-containing species for the oxidation and removal of CO intermediates.The synergistic effect between Pt and Te can promote the formation of electron-rich Pt surfaces,which weaken the adsorption ability of the catalyst for CO poisoning species and increased the charge transfer rate,thereby improving the catalytic performance of alcohol oxidation.(2)We demonstrated the successful synthesis of noble metal Pd nanoparticles supported on Te nanorods(Te/Pd)catalysts and application research on the catalytic performance of MOR had also been conducted.The Pd nanoparticles were reduced and grown on Te nanorods by ethylene glycol reduction method.Through physical characterization and electrochemical tests,the Pd/Te catalysts can keep the nanorods morphology well and exhibit excellent catalytic activity and stability for methanol electrooxidation,along with good resistance to CO poisoning in alkaline media.The reason for the excellent performance of the catalyst may be due to the rearrangement of the electron arrangement around the active site of Pd.The synergistic effect of Pd and Te can lead to an increase in the content of Pd0 and the formation of electron-rich Pd surface,which can effectively promote the oxidation of CO poisoning intermediates.(3)Ru nanoparticles assembled as a shell over semimetal Te nanorod surfaces(Te@Ru)catalysts were successfully prepared and their activities for HER had been studied.A composite Te@Ru catalyst with Te nanorod as the core and metallic Ru nanolayer as the shell was prepared by a two-step hydrothermal reduction method.In 0.5 M H2SO4 solution,the Te@Ru catalyst exhibited good catalytic capacity and stability for HER,which needs the overpotential of 86 mV when the current density was 10 mA cm-2,much lower than that of the home-made Ru catalyst(130 mV).By comparing the specific activity and turnover frequency,the Te@Ru had the best intrinsic activity,which may be due to the formation of a special core-shell structure and the synergistic effect between the metal Ru and the semimetallic Te in the catalyst system.The metallic Ru nanolayer can expose more effective Ru active centers,thereby effectively improving the catalytic reaction.