Preparation Of Nickel-based Catalysts And Their Electrochemical Application

Fuel cells is considerable as an ideal choice for green power source in the future, due to wide range of sources, non-pollution emissions, structure simplicity and high energy conversion efficiency. Direct methanol fuel cells?DMFCs? have attracted considerable attention because methanol is fuel source with a higher energy density, methanol can be stored more easily than hydrogen. DMFC electrode materials are mainly noble metals, such as Pt and Pd, but the noble metals have the disadvantages of the high cost, lacking of resources and Pt-based electrodes are the poisoning resulting from surface-absorbed CO intermediates spices. Alkaline DMFCs use non-noble metals such as Ni, Ag and Co and Alkaline DMFCs may be less sensitive to poisoning of CO intermediate products. Electrocatalytic/photocatalytic H₂-production from water splitting is of great importance in the research of the global energy and environment issues. Water splitting is a combination of two half-reactions, the hydrogen evolution reaction?HER? and the oxygen evolution reaction?OER?. OER is kinetically sluggish and leads to high anode over-potential, more energy losses, consumes high energy. OER usually contain precious metals catalysts, but precious metals are scarce and high cost, and their large-scale applications is limited. OER under alkaline conditions can use of inexpensive metals catalysts, such as Ni, Co, Mn and their oxides/hydroxides. Electrochemical capacitor is considered as an ideal choice for energy storing device, due to higher energy capacity, rapid charging ability and long life. Electrochemical capacitor electrode materials include the specific surface area of the carbon materials, metal oxides/hydroxides and conducting polymers. The development of direct methanol fuel cells, electrochemical capacitors and OER were limited by the development of electrode material. The application of nickel-based catalysts materials in alkaline DMFCs, electrochemical capacitor OER has been paid more and more attention. Nickel-based catalysts have been successfully synthesized by using different methods, and for alkaline DMFCs, electrochemical capacitor and the OER. The details are as follows:1. Microporous nickel phosphate VSB-5 and G-doped Ni-P-O composites were prepared by the hydrothermal method. The obtained NiPO/G-X catalysts were characterized by SEM, Raman, XRD, UV-Vis, and XPS. The electrochemical performance for the methanol oxidation was investigated by CV curves and chronoamperometry curves. VSB-5 and G-doped Ni-P-O composites were used for the oxygen evolution reaction in alkaline solution. The electrochemical performance for the OER was investigated by CV curves and LSV curves.2. NiP/G-X were prepared by the Ni PO/G-X with 500 and kept for 1 h in a continuous H? 2 flow. The obtained NiP/G-X catalysts were characterized by SEM, Raman, XRD, and FTIR. The electrochemical performance for the methanol oxidation was investigated by CV curves and chronoamperometry curves. NiP and NiP/G composites were used for the oxygen evolution reaction in alkaline solution. The electrochemical performance for the OER was investigated by CV curves and LSV curves.3. Using the sodium borohydride as the source of alkali and boron. B-Ni?OH?₂ catalyst was prepared by a one-pot liquid-phase method. B-NiO material was prepared by thermal decomposition of B-Ni?OH?₂. We could obtain the Ni?OH?₂ catalyst by replacing sodium borohydride with sodium hydroxide. NiO material was prepared by thermal decomposition of Ni?OH?₂. The obtained B-NiO catalyst was characterized by XRD, XPS, TEM, SEM, and BET. Electrochemical capacitor performance was investigated by CV curves and galvanostatic discharge curves.4. Mesoporous NiPO-1, NiPO-2 and Si-NiPO-1, Si-NiPO-2 composites was used for the oxygen evolution reaction in alkaline solution. The electrochemical performance for the OER was investigated by CV curves and LSV curves.