铁系金属硫化物的多重调控制备及其电催化析氢构效关系探究

Developing low cost and high active electrocatalysts based on non-noble metals is the key to reduce the large overpotential of hydrogen evolution reaction (HER) and produce hydrogen in large-scale practical application. Ferrious metal (Fe, Co, Ni) sulfides have attracted extensive attention because of inborn advantages of inexpensive, high earth-abundance and well stability. However, it remains big challenges to synthesize sulfides with controllable composition, phase and micro-nanostructure and to investigate their structure-performance relationship. Furthermore, the HER activity of sulfides is far behind from those of noble metal-based catalysts. Regarding of the aforementioned problems, this project proposes the hydro/solvothermal synthesis of metal (Fe, Co, Ni) sulfides with multi-controllable accurate metal/sulfur ratio, crystal symmetry and morphology by introducing the “growth-moderate” or ”phase-control” agents (mechanism: through chelating metal ions to indirectly control their binding extent with sulfide species and also can stabilize the formed nanocrystalline phases) and surfactants together with the adjustment of the other experimental parameters (e.g., reaction temperature, time and solvents). Based on the electrochemical HER activities of a series of synthesized catalysts, the relationship between the material properties and the intrinsic HER behavior and corresponding mechanism will be further systematically investigated, thus, optimizing the structure and morphology and enhancing the catalytic reaction kinetics to construct low cost and highly efficient sulfides-based HER catalysts with activities that are comparable to platinum.

开发低成本、高活性的非贵金属析氢催化剂是降低析氢反应过电位、实现大规模制氢的关键。铁系金属硫化物催化剂具有低成本、资源丰富、稳定性好等先天优势，受到研究者们的广泛关注。然而，该类材料在化学组分、晶型和微结构可控合成，结构-性能构效关系探究等方面均面临巨大的挑战，其析氢活性与贵金属催化剂间还存在着明显差距。针对上述问题，本项目提出在水热/溶剂热合成过程中引入“反应阻断剂”及“晶相控制剂”（作用机理：通过螯合金属离子，间接控制其与硫物种结合程度并能稳定已形成纳米晶物相）和表面活性剂等，配合调整反应温度、时间及溶剂等实验参数，以实现铁系金属硫化物金属/硫精准化学计量比、晶体对称性和微观形貌等的多重调控制备。基于材料体系在电催化析氢反应中的活性表现，构建材料属性与宏观电化学本征析氢行为和机制间的关联，进而优化结构和形貌，提升催化反应动力学，构筑媲美贵金属铂催化剂活性的廉价、高效硫化物析氢催化材料。

铁系金属硫化物材料具有资源丰富、低成本和潜在的电催化析氢活性而备受关注，但其在组分、晶型调控制备，结构-性能构效关系及其析氢催化活性提升以媲美贵金属催化剂等方面仍然面临着巨大的挑战。本项目发展了软模板辅助的水热反应法和管式炉蒸气热硫化等策略，实现了铁系金属硫化物空心结构纳米球材料成分、物相、表面结构和化学价态等的调控制备，揭示出水热法中二硫化碳作为硫源和反应模板剂在反应过程中的双重角色和反应机理模型。结合理论模拟和电化学手段分析，阐明了Co-S（CoS、Co9S8、CoS2）和Ni-S（NiS、Ni3S4、NiS2）体系中黄铁矿型CoS2和NiS2由于丰富的金属-S6八面体配位结构、良好的电子传输特性和较大的比表面积而表现出最优的HER活性和最快的反应动力学特性。在此基础上，通过元素掺杂、形貌优化和表面修饰等策略进一步提升二硫化钴基电催化剂的析氢活性，开发出导电基底上原位负载Zn-Co-S纳米针阵列和Pt/CoS2复合电极材料，获得媲美商业化贵金属Pt/C催化剂的活性和更加优异的稳定性及数倍高的Pt质量活性，为低铂和非铂电催化剂提供了新的材料体系。研究成果将为其他金属硫化物纳米结构的控制合成及高效廉价析氢电极材料的研发提供重要理论依据。在本项目的资助下，已在《Adv. Mater.》、《Angew. Chem. Int. Ed.》、《Adv. Energy Mater.》、《Nano Energy》等重要期刊上发表SCI论文15篇，其中IF>10论文8篇，一区论文13篇，入选封面论文2篇/ESI高被引论文5篇。第一发明人申请专利4件，项目负责人入选2018年第四届中国科协青年人才托举工程；受邀参加，如2019绿色化工能源国际研讨会(IGCETC 2019)、中国有色金属学会2018青年科技论坛等并做学术报告，圆满完成项目预定目标。