| Advanced electrocatalysis technology is of much importance in various electrochemical energy conversion and storage system,where the key point is the design and synthesis of highly efficient electrocatalysts.Ordered mesoporous material with rich pore structures,nanoscale frameworks,and high specific surface area is a class of highly promising electrocatalyst candidates.In this thesis,a series of ordered mesoporous cobalt-based oxide and sulfide semiconductors with different mesostructure and framework chemical composition have been successfully synthesized and their potentials in glucose fuel cells and electrocatalytically splitting water for oxygen evolution reaction have been systematically explored,achieving a significantly enhanced performance.The effect of the porosity and framework composition of the mesoporous cobalt-based semiconductors on their electrochemical performances has been investigated.A series of ordered mesoporous nickel cobaltate semiconductors(NiCo2O4-X)with different porosities have been synthesized by using ordered mesoporous silica(KIT-6-X)aged at different hydrothermal temperatures(X=40,80,100,140 ℃)as the hard template and of cobalt(Ⅱ)nitrate and nickel(Ⅱ)nitrate hydrates as the precursor.Among them,NiCo2O4-40 has a larger pore size(12 nm)and a higher specific surface area(142 m2·g-1),while other ordered mesoporous nickel cobalt oxide has smaller mesopores(3-4 nm)and relatively lower specific surface area(NiCo2O4-80,130 m2·g-1;NiCo2O4-100,115 m2·g-1;NiCo2O4-140,89 m2 g-1).Ordered mesoporous nickel cobaltates were systematically evaluated as anode electrocatalytic materials for glucose fuel cells,where the NiCo2O440-based cell showed an open circuit voltage of 0.74 V and maximum power density of 2.07 mW·cm-2,significantly superior over other ordered mesoporous nickel cobaltate-based cells(NiCo2O4-80,1.46 mW·cm-2;NiCo2O4-100,1.27 mW·cm-2;NiCo2O4-140,0.96 mW·cm-2)and common bulk nickel cobaltate-based cell(28 m2·g-1,0.80 mW·cm-2).This may be since NiCo2O4-40 with both high specific surface area and large mesopore could provide more active site and facilite the diffusion and transport of glucose for the electro catalytic reaction,leading a better performance.For comparison,other ordered mesoporous cobalt-based semiconductors such as ZnCo2O4-40(142 m2·g-1),CuCo2O4-40(130 m2·g-1),Co3O4-40(135 m2·g-1)were also synthesized,whose corresponding maximum power density is 1.52 mW·cm-2,1.49 mW·cm-2 and 0.94 mW·cm-2 respectively,indicating that the manipulation of metal cations in the frameworks has an important impact on the performance of the corresponding glucose fuel cells.A series of ordered large-pore mesoporous nickel cobaltate-based solid solution(109～149 m2·g-1)with doping Cr,Fe and Ga were synthesized by similar hard-templating methods,and a series of ordered large-pore mesoporous cobalt nickel sulfide solid solution(113～156 m2·g-1)were also synthesized by combining hard-templating method with high-temperature vulcanization.The potential of the assynthesized ordered large-pore mesoporous cobalt-based solid solutions in glucose fuel cells and electrocatalytically splitting water for oxygen evolution reaction(OER)was evaluated,which suggests that the manipulation of metal cations in the frameworks would not only affect the performance for glucose fuel cell but also alter OER performance.A series of ordered mesoporous cobalt manganese oxides with different porosities and framework compositions were also synthesized by similar hard-templating methods.Among them,MnCo2O4-40 has a large pore size(12.6 nm)and a high specific surface area(126 m2·g-1),which was systematically evaluated as a cathode electrocatalytic material for glucose fuel cells.An open circuit voltage of 0.75 V and maximum power density of 1.76 mW·cm-2 have been achieved over MnCo2O4-40-based cell,significantly superior over other ordered mesoporous cobalt manganese oxide-based cells and common bulk cobalt manganese oxide-based cell(3 m2·g-1,1.17 mW·cm-2)as well as commercial Pt/C electrocatalysts(1.45 mW·cm-2). |
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