Browsing by Author "Jiang, SP"

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    High-performance perovskite composite electrocatalysts enabled by controllable interface engineering
    (John Wiley & Sons, Inc, 2021-06-17) Xu, XM; Pan, YL; Ge, L; Chen, YB; Mao, X; Guan, DQ; Li, MR; Zhong, YJ; Hu, ZW; Peterson, VK; Saunders, M; Chen, CT; Zhang, HJ; Ran, R; Du, AJ; Jiang, SP; Zhou, W; Shao, ZP
    Single-phase perovskite oxides that contain nonprecious metals have long been pursued as candidates for catalyzing the oxygen evolution reaction, but their catalytic activity cannot meet the requirements for practical electrochemical energy conversion technologies. Here a cation deficiency-promoted phase separation strategy to design perovskite-based composites with significantly enhanced water oxidation kinetics compared to single-phase counterparts is reported. These composites, self-assembled from perovskite precursors, comprise strongly interacting perovskite and related phases, whose structure, composition, and concentration can be accurately controlled by tailoring the stoichiometry of the precursors. The composite catalyst with optimized phase composition and concentration outperforms known perovskite oxide systems and state-of-the-art catalysts by 1–3 orders of magnitude. It is further demonstrated that the strong interfacial interaction of the composite catalysts plays a key role in promoting oxygen ionic transport to boost the lattice-oxygen participated water oxidation. These results suggest a simple and viable approach to developing high-performance, perovskite-based composite catalysts for electrochemical energy conversion. © 2021 Wiley-VCH GmbH
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    Investigating HPA functionalized mesoporous silica materials for use as high temperature proton exchange membranes
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2012-12-07) Lamb, K; De Marco, R; Jiang, SP; Peterson, VK
    High temperature (>100°C) proton exchange membrane fuel cells (HT-PEMFC) are solid energy conversion devices that electrochemically convert chemical energy (eg. from alcohols) into electricity. HT-PEMFCs are more efficient than low temperature PEMFCs due to elimination of carbon monoxide poisoning and faster oxidation kinetics. Various types of proton exchange membranes have been explored, such as nonfluorinated hydrocarbon polymers, or hybrid Nafion-based membranes. While these materials have their advantages, they dehydrate at high temperatures, leading to a significant reduction in proton conductivity. Recently, we found that heteropolyacids (HPA) such as tungstophosphiric acid (abbreviated as HPW) can be used to functionalize ordered mesoporous silica (MSN) to make nanocomposites PEMs. While these nanocomposites have shown promising preliminary results as HT-PEMs, the ways in which changes to the structure of these materials affect the proton exchange properties are largely unknown. Analysis techniques such as ex- and in-situ HR-FTIR, SAXS, SANS, and QENS will be used to build an understanding of the membrane structure and proton diffusion mechanisms of these HT-PEMs, thereby determining the best performance HPA-MSNs for use in direct alcohol fuel cells.
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    Neutron and synchrotron characterisation techniques for hydrogen fuel cell materials
    (Australian Nuclear Science and Technology Organisation, 2021-11-24) Lamb, K; Kirby, N; Bartlett, JR; Peterson, VK; Appadoo, D; Jiang, SP; De Marco, R
    Hydrogen fuel cells and other renewable energy technologies have specific materials and functional needs which can be more fully understood using neutron and synchrotron characterisation techniques. In this presentation, a materials which has applications in proton exchange membranes is studied with a variety to techniques to develop a comprehensive understanding of the functional-structural relationship. The materials used here is phosphotungstic acid (HPWA) stabilised in an ‘inert’ mesoporous silica host material. This aim of this research is to develop an understanding of the interaction between the HPWA and the silica and whether different structures or surface chemistries have advantageous or detrimental effects. Two silica symmetries used were Ia3 ̅d (face centred cubic bi-continuous) and P6mm (2D hexagonal with cylindrical pores) which were vacuum impregnated with solutions of HPWA in a range of concentrations. The resulting powder samples were then analysed using small angle x-ray scattering (SAXS), inductively coupled plasma emissions spectroscopy (ICP-OES), nitrogen gas adsorption/desorption, near edge X-ray absorption fine structure (NEXAFS/X-ray absorption near edge structure/XANES) of the O and Si k-edges, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, and then formed into a disk using polyethylene as the binder for electrical impedance spectroscopy (EIS). The insights gained from this systematic study indicate that the surface chemistry of the silica host has a significant effect on the performance, uptake and interactions with the HPWA anions, where lower concentrations of HPWA result in stronger host:HPWA interactions but lower conductivity. © The Authors