Metal-oxide Interface Constructing And Electrocatalytic Performance Tuning

As the green energy of the 21st century,the best application of hydrogen energy is to convert hydrogen energy into electrical energy through fuel cells.However,the largescale commercial application of fuel cells is still great challenges.Among them,proton exchange membrane fuel cell(PEMFC)anodes have high requirements for purity of hydrogen,and trace impurities(such as CO,H2S)will cause severe poisoning even inactivation of the anode catalyst.Therefore,to solve the robustness of the fuel cell anode hydrogen oxidation(HOR)catalyst it is decades of scientific issue for researchers.To improve the CO tolerance of fuel cell,traditional strategy is to control the composition of catalyst(eg.PtRu alloy),atomic arrangement and electronic structure of the catalysts to increase the CO oxidation performance and weaken the CO adsorption on Pt surface.However,the working potential of the anode in fuel cell is quite low,and the CO has a strong adsorption on the Pt surface.Therefore,this strategy cannot solve the poisoning problem of fuel cell in practical applications.On the other hand,the exploration and development of efficient catalysts for hydrogen production by water electrolysis can also solve the robustness of the anode in fuel cell from the source.However,compared to scarce Pt catalysts,researchers have developed many non-Pt for water electrolysis,which still have large overpotential and poor stability by comparing to Pt catalyst.Therefore,it is of great significance to develop new ideas for HER catalyst design.In this research,we develop new strategies for catalyst design based on the metaloxide interface.On the one hand,we can improve the CO resistance of anode catalysts by constructing metal-oxide interfaces that are difficult for CO adsorption;on the other hand,we developed novel design strategy to control the electronic properties of the metal-oxide interface to promote the reactivity and stability of the catalyst and increase the advantages of hydrogen production from water electrolysis.The main results are as follows:(1)Both electrochemical square wave and chemical oxidation methods for constructing a model catalyst Ru@RuO2 with Ru-RuO2 interface was developed.The CO-tolerance at HOR experiments showed that the constructed Ru@RuO2 model catalyst has high CO tolerance.After 2 h stability test in H2 with 5%CO,there is still 40-50%of HOR activity retained in 0.1 V vs.RHE.The XPS and In-situ ATR-IR results show that high CO resistance is closely related to the interface water,which is speculated that RuO2 promotes the water adsorption at the interface,thus blocking the CO adsorption and improving the CO tolerance.(2)Chemical oxidation treatment of commercial PtRu/C to construct PtRu-RuO2 interface via the Ru surface segregation.After electrochemical tests,the PtRu-RuO2 interface building on the PtRu/C surface almost did not influence the HOR activity of PtRu@RuO2 catalyst.The CO tolerance tests show that 85%of the HOR activity remained after 20 h at 0.1 V vs.RHE in H2 with 1000 ppm CO,indicating great improvement on the CO resistance of PtRu@RuO2 catalyst.The CO oxidation performance of PtRu@RuO2 is much weaker than that of commercial PtRu/C catalyst,which indicates that the improvement of CO tolerance is not coming from the bifunctional mechanism,but similar to Ru@RuO2,which is also related to the strongly adsorbed interface water.(3)By introducing a strong reduced Ti2O3 support and utilizing its electron-donating nature,to control the electrons transfer from titanium oxide to Ru at the rutheniumtitanium oxide interface,and synthesize the electron-rich Ru in Ru/r-TiO2 catalyst.This catalyst exhibits greater alkaline HER performance than commercial Pt/C catalysts with a small overpotential 15 mV at 10 mA cm-2 and high TOF 8.74 s-1 at 100 mV.Combining DFT theoretical calculation results show that t Ru/r-TiO2 catalyst not only improves the hydrolysis dissociation kinetics,but also accelerates the dissociation and adsorption of the intermediate OH*at the interface.This research has developed a new strategy for tuning the electronic properties of the metal-oxide interface for HER catalysts.(4)Detection the ·OH radicals in the Fe/N/C oxygen reduction process by using coumarin as a fluorescent probe was developed.The experimental results show that·OH radicals are generated during the Fe/N/C oxygen reduction process.As the potentials decreased from 0.7 to 0.6 V,and amount of·OH radical increases first and then decreases.This variation of ·OH amount is largely different from that of H2O2,and the latter increased with decreasing potentials monotonically,which indicating that the·OH radicals generated during the Fe/N/C oxygen reduction process did not originate from the decomposition of H2O2.The research provides a new insight for the stability study on Fe/N/C catalysts.