Polymer-assisted approach to LaCo1-xNixO3 network nanostructures as bifunctional oxygen electrocatalysts
Polymer-assisted approach to LaCo1-xNixO3 network nanostructures as bifunctional oxygen electrocatalysts
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DOI：
10.1016/j.electacta.2018.11.075
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发表时间：
2019-02
影响因子：
6.6
通讯作者：
Haizhen Wang;Weichuan Xu;Stephanie Richins;Kevin Liaw;Litao Yan;Meng Zhou;Hongmei Luo
中科院分区：
文献类型：
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作者：
Haizhen Wang;Weichuan Xu;Stephanie Richins;Kevin Liaw;Litao Yan;Meng Zhou;Hongmei Luo
由于人口增长和经济增长导致的化石燃料消耗造成的能源枯竭，刺激了包括燃料电池和金属-空气电池在内的电化学储能系统的研究。氧电催化包括氧还原反应(ORR)和析氧反应(OER)，决定了这些电化学能量系统的性能。然而，这两个反应的缓慢动力学仍然限制了它们的性能，甚至限制了这些电化学储能系统的商业化。因此，开发非贵金属基氧催化剂，特别是同时具有OER和ORR双功能的氧催化剂是非常有必要的。在本报告中，我们采用聚合物辅助的方法合成了LaCoO_3基钙钛矿纳米粒子，这些纳米粒子相互连接在一起形成了多孔的网络结构。X-射线衍射分析表明，由于Ni3+的离子半径比Co3+的离子半径大，用Ni取代Co会导致晶格膨胀。这些材料在0.1 M KOH水溶液中的电催化活性表明，通过在B位引入镍可以改善LaCoO_3的氧化还原性能，同时也将提高它们的氧化还原性能，从而使这些钙钛矿氧化物对氧化还原和氧化还原都表现出较好的双功能电催化活性。镍掺杂对催化剂性能的提高可能是由于两种过渡金属的协同作用，形成了新的氧化还原对Ni3+/Ni2+以及较高的Co3+/Co2+比，从而促进了氧在催化剂表面的吸附，提高了Cosingle Bondo键的强度。我们的研究不仅引入了聚合物辅助的方法来制备网状结构的钙钛矿纳米粒子，而且强调了B位金属掺杂作为一种简单的策略来提高其双功能氧催化活性的重要性。
Energy depletion caused by the consumption of fossil fuels due to increasing population and economic growth has stimulated intense research on electrochemical energy storage systems, including fuel cells and metal-air batteries. Oxygen electrocatalysis, including both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), dominates the performance of these electrochemical energy systems. However, the sluggish kinetics of these two reactions still limits their performance and even the commercialization of these electrochemical energy storage systems. Therefore, development of non-precious metal-based oxygen catalysts, especially with bifunctionality for both OER and ORR, is greatly demanded. In this report, polymer-assisted approach has been employed to synthesize LaCoO3-based perovskite nanoparticles, which interconnected together to form porous network structures. X-ray diffraction indicated that replacement of Co with Ni would lead to a lattice expansion due to larger ionic radius of Ni3+as compared to that of Co3+. The electrocatalytic activity of these materials in 0.1 M KOH aqueous solution showed that ORR performance of LaCoO3can be improved through incorporation of Ni into the B-site while their OER performance will also be enhanced which renders these perovskite oxides to exhibit better bifunctional electrocatalytic activity for both OER and ORR. The enhanced performance with Ni-doping might be due to the synergistic effect from the two transition metals as a result of the formation of new redox couples Ni3+/Ni2+as well as the higher Co3+/Co2+ratio, which could promote adsorption of oxygen on the catalytic surface with improved the Cosingle bondO bond strength. Our study not only introduces polymer-assisted method to prepare network structured perovskite nanoparticles, but also highlights the importance of B-site metal doping in perovskites as a simple strategy to enhance their bifunctional oxygen catalytic activities.