面向氢/氧电催化的多功能钴-磷(氧)/氮掺杂碳三维多孔纳米材料的设计与可控制备

Noble metals such as Pt, Ir and Ru, which pocess high performance in electrocatalysis of hydrogen/oxygen (ORR/OER/HER), have limited practical application because of their high cost and limited function. In this project, we develop a series of 3D porous nitrogen-doped carbon materials and their composites with nanostructural Co phosphides/oxides (Co-P(O)/N-C) through self-assembly on templates followed by coupling metal under site protection. The pore structure, the specific surface area, the heteroatom doping, and valence bond as well as surface structure of the combined Co phosphides/oxides are adjusted and optimized with respect to the ORR and HER/OER activities, respectively, to achieve the multifunction of the composites. With the use of preferential adsorption of ions/molecules, the coordination structure related to ORR、OER and HER performance can be seperated and analyzed. Furthermore, the active sites for electro-catalysis can be revealed as a guidance of the design towards highly efficient non-noble catalysts. Innovation of this project lies in the construction of the catalytic material with 3D porous structure and achievement of multifunction by site-protected two-step fabrication processes. It is expected to obtain 2-3 new highly efficient multifunctional non-noble metal catalysts, and to investigate their potential application in zinc-air battery and electrolysis equipment for producting hydrogen/oxygen through the project implementation.

氢/氧电催化中（ORR/OER/HER）具有较好性能的Pt，Ir和Ru等贵金属因成本高昂，且存在功能局限性，其应用受到极大的限制。本项目拟通过模板表面自组装，以及位点保护金属耦合反应过程，开发多种三维多孔结构的氮掺碳材料及其与钴磷化物或氧化物的耦合材料。过程中分别以ORR和HER/OER性能为导向，完成对材料孔结构，比表面积和杂原子掺杂类型，以及耦合钴磷/氧化物的价键类型及表面结构等参数的分步调控与优化，实现其多功能电催化效应。同时采用离子/分子选择性吸附手段，分离解析与ORR、OER和HER性能相关的表面配位结构，揭示电催化活性中心，为设计高效非贵金属电催化剂提供理论指导。项目的创新点在于三维多孔催化材料的构筑以及材料多功能效应的位点保护分步调控。经本项目研究，预计可筛选出2-3种新型高效的多功能电催化剂，并初步考察其在锌空气电池和电解水制氢制氧装置中的潜在应用。

氢能和金属空气电池等新能源技术涉及到氢析出反应（HER）和氧还原及析出反应（ORR及OER），需要昂贵的贵金属催化剂。采用非贵金属材料不仅可大幅降低成本，也可进一步带动未来清洁能源的发展。.本项目研究内容、关键数据、结果和意义总结如下：.（a）C3N4模板/二甲基咪唑、氧化石墨烯和钴盐复合碳化，制备氮掺杂碳管包覆Co/石墨烯3D复合材料和Co-N单元复合石墨烯材料。ORR性能达到与商业Pt/C相当，而HER与OER性能分别接近商业Pt/C与Ir/C性能，其10 mA cm-2 电流密度下的过电位分别为205mV 与360mV。锌空气电池可进行超过1000次循环。电解水测试中氢气与氧气析出速率分别为0.035 mL min-1和0.017 mL min-1。该催化剂相对于贵金属催化剂具有价格便宜，多功能性能好等优势。.（b）以Co等金属有机框架化合物为前驱体，磷化制备CoFe氧磷化物材料和CoPO材料，研究OER和电解水性能。两个材料在10 mA cm-2时OER过电位分别只有291和280mV； CoPO在全水分解反应电压为1.52V（10mA cm-2）。.（c）Co纳米单与Fe氧化物或单原子Ir复合，制备Co/Fe异质结材料和Ir@CoOx单原子材料，OER性能均比Ir/C好。机制研究揭示了异质结材料中Co-O-Fe高活性物种、大量局域晶化区域，以及Ir@CoOx单原子纳米单材料中Ir和Co原子的协同机制，对OER具有促进作用。表明Co纳米单是良好的基底，有利于后续研究的拓展。.（d）Ni12P5/NCNT光响应OER/ORR双功能材料光电催化研究。所组装的锌空气电池在无光条件下电池充放电电位差为0.7V，光照后该差值降低至0.68V，具有明显的光响应性能。该工作为光电响应锌空气电池的提供了研究模型。