利用多酸设计和制备新型高效非贵金属电解水制氢催化剂

The exploration of new clean and renewable energy is the currently most important project for the national economy and the people’s livelihood. Hydrogen (H2) has been considered as an ideal alternative to fossil fuels due to it being clean, renewable and having high gravimetric energy density. The hydrogen evolution reaction (HER) via an electrocatalytic water-splitting method is a promising approach for hydrogen production owing to its high energy conversion efficiency. A key problem of this method is seeking highly active electrocatalysts that can decrease the overpotential and promote the HER performance. Pt is now the most efficient electrocatalyst for the HER, but its low abundance and high cost prevent large scale applications. Thus, the development of non-noble metal catalysts with low cost and high catalytic activity has attracted great research interest and become a challenging project in this research field. In our project, the nanoscale polyoxometalates (POMs) with enriched molybdenum & tungsten metal centers will be used as the precursors to design and prepare new non-noble-metal electrocatalysts for HER. In one aspect, highly reduced POMs via controllable reduction method and new type of POM-based metal-sulfur clusters will be synthesized as new molecular electrocatalysts for HER. In another aspect, POMs will be employed as a molecular assembly platform to precisely tune various metal components and structural features. Furthermore, the combination of POMs with a series of organic dopants (C, N, P, S etc), dispersants and carrier materials will lead to various assemblies that can disperse POM units at the molecular level, which will be annealed at limited range so as to obtain new type of nanoscale low-valent metal (Mo/W) oxides, metal carbides, phosphide, and sulfide electrocatalytic materials. The effect of POM precursors on the component, pattern, phase and electrocatalytic activity of these electrocatalysts will be investigated in detail. Based on our project, brand new type of high efficient non-noble-metal electrocatalysts for HER via the electrocatalytic water-splitting method will be explored and bring the breakthrough for this research field.

开发清洁和可再生新能源是惠及国计民生的重大研究课题。氢能作为理想的新能源，其最具发展潜力的制备技术是电解水制氢。该技术的瓶颈之一是所采用的贵金属铂电催化剂稀缺，阻碍大规模工业化。开发高效、稳定且储量丰富的非贵金属电催化剂成为该领域的重要挑战。本项目拟利用富含丰产元素钼、钨且具有均一纳米尺寸的多酸为前驱体，设计制备新型高效非贵金属电解水制氢催化剂。一方面，对多酸本身控制还原或引入硫原子，构筑新型高还原态多酸和多酸基硫簇分子电催化剂；另一方面，利用多酸分子设计平台，精细调整多酸的组成、结构以及多酸与各类有机掺杂源（碳、氮、磷、硫等）、分散剂和附载材料的结合方式，合成各类多酸基前驱体，并进行控温热解，制备新型低价金属(钼/钨)氧化物、金属碳化物、磷化物、硫化物等电催化剂。研究多酸前驱体对电催化剂组成、形貌、晶相及电催化活性的影响，总结析氢电催化剂设计与制备的内在规律，实现电催化产氢领域新突破。

氢能是“后石油”时代重要的清洁能源。当前氢能生产主要依靠烷烃重整和煤气化，电解水制氢可摆脱对化石资源依赖，其中的重要基础科学问题之一是研发出可替代贵金属铂的高效价廉催化剂。若使理论上本征活性与铂相似的非贵金属催化剂真正发挥出超越铂的电催化性能，需要对催化材料同时进行组成、结构、形貌、晶相、尺寸等多维度调控，是该领域基础研究中的一项重要挑战。. 我们借助多酸分子在上述研究领域取得重要进展。首先，利用多酸与金属氧化物催化剂结构的相似性，采用结构明确的铂取代多酸首次在分子水平上揭示了氧化态铂的高效电催化产氢机理；其次，将多酸用做“分子预组装平台”，提出一种制备多界面复合纳米电催化剂的新途径。通过调整多酸的组成、电荷、结构以及多酸与各类有机配体和掺杂源的不同复合方式，获得各种多酸基自组装体；再进一步通过热解方法，制备了一系列新型多界面纳米复合电催化剂，展现出高性能电催化析氢活性，并揭示了各类复合型催化剂的协同产氢新机制；第三，获得性能优异的电催化剂，可用于电解海水制氢和与氯碱工业联产制氢，为低成本制氢技术提供新方案。. 在电解水制氢技术的关键科学问题上实现突破不仅可促进氢能的绿色、可持续工业化制备，还可为我国新能源战略顺利实施提供重要技术结点。例如氢能生产可以与风能、海洋潮汐能结合，使不易并入国家电网的垃圾电转化为高品质能源；氢能生产与传统的氯碱工业、或新兴的生物质能联合，会进一步降低生产投入和能耗，展现可观的应用前景。可以预见，电解水制氢是连接和优化我国未来各类新能源开发、存储和有效利用的关键技术环节，具有重要战略意义。