氮硫共掺杂多孔碳负载过渡金属硫化物的可控构筑及氧还原催化性能研究

The synthesis of low cost, highly efficient M/N/C electrocatalysts is the research focus in the field of non-precious metal catalysts (NPMCs) for the oxygen reduction, and plays a vital role in the development of fuel cells. However, the catalytic activities of the M/N/C electrocatalysts are still inferior to that of precious metal catalysts due to low active catalytic sites, especially in acid medium. Herein, we design and synthesize highly efficient electrocatalysts composed of transition metal sulfides (TMSs) and nitrogen and sulfur dual-doped porous carbon (N, S-PC) based on micro-levels. In the TMSs/N, S-PC catalysts, the microstructures and morphologies of carbon matrices prepared using the sacrificial template method are dependent on the templates, and TMSs are successfully loaded onto carbon matrices based on coordination theory and/or precipitation-dissolution equilibrium, of which the loading types and structures can be controlled via altering the loading methods and conditions. Then, the intrinsic relationship and discipline between the composition, structure and catalytic activity are systematically investigated via the microstructure characterization and electrochemical measurement. On that basis, we analyze the catalytic kinetics, investigate the catalytic roles and synergistic effects of TMSs and N, S-PC, and propose the catalytic mechanisms. We envision that the sucessful completeion of this proposal can provide new insights on the fabrication of an advanced NPMCs with outstanding catalytic activity, long-term stability, and excellent selectivity in acid and alkaline media, which is of great significance for the development of low cost, high performance fuel cells.

开发廉价、高效M/N/C（M=Fe、Co……）催化剂，是非贵金属氧还原催化剂领域研究的重点和难点，对推动燃料电池的发展具有重要意义。然而，M/N/C催化位点活性较低，导致催化性能逊色于贵金属催化剂，尤其在酸性介质中，从而限制了其应用。本项目从微观层面上，设计并构建了氮硫共掺杂多孔碳负载过渡金属硫化物的高效复合催化剂。采用牺牲模板法实现碳材料微纳结构和形貌的精确调控，根据配位或沉淀溶解平衡理论，通过改变负载方法和条件实现过渡金属硫化物的负载类型和结构可控，进而利用微观表征手段和电化学测试方法系统研究催化剂的“组成—结构—性能”间的内在联系和规律，探究过渡金属硫化物和碳材料的催化作用及协同效应，揭示催化机理，为构建高活性、高稳定性、高选择性的非贵金属催化剂提供新思路和新方法，为制备廉价高性能燃料电池奠定坚实基础。

氮、硫共掺杂多孔碳载体负载过渡金属硫化物有望取代用于氢燃烧电池和金属-空气电池中的铂基贵金属催化剂，从而降低制造成本和加快商业化进程。本项目以调控碳载体的结构、掺杂类型以及过渡金属硫化物在碳载体上的负载方式为研究对象，开发了自模板法和牺牲模板法制备具有大比表面和丰富孔道结构的氮、硫共掺杂碳多级结构（双层多孔纳米管，纳米绣球、海胆状、话梅状、和纳米泡沫等）的方法和技术，通过设计路线和利用多巴胺分子的自聚合反应以及与过渡金属空d轨道间的强配位作用实现了过渡金属硫化物在碳载体上的表面负载、镶嵌、和碳层包覆；研究了碳载体和过渡金属硫化物的掺杂类型对氧还原催化性能的调控机制，总结了过渡金属硫化物的负载方式对催化稳定性的影响规律，明晰了碳载过渡金属硫化物催化剂的“组成—结构—性能”间的内在联系和规律，开发出金属质量活性和氧还原半波电位与铂基贵金属相媲美的碳载过渡金属硫化物催化剂；成功组装了功率密度高达510.7 mW cm-2的阴离子交换膜H2-O2燃烧电池和214.7 mW cm-2的可充式锌空电池，且电池寿命达300小时以上。本项目的研究工作揭示了碳载体和过渡金属硫化物组分的结构、掺杂类型以及负载方式在催化氧还原反应中的作用，为构筑高活性、高稳定性的碳载过渡金属硫化物氧还原电催化剂提供了新策略，为组装廉价且高性能阴离子交换膜氢燃烧电池和可充式锌空电池奠定了坚实基础。