Low-Coordinate 3d Metal Complexes as Alternatives to Platinum Group Metals for Hydrogen Evolution Reaction

通过析氢反应(HER)还原水生产氢气是一种很有前途的碳氢原料的可持续替代方案。目前的技术水平使用铂，因为它以低过电位和高周转频率运行。然而，铂的低丰度(地壳中37 ppb)导致了高昂的经济和环境成本，其高毒性导致产生大量的废物。使用具有丰富的稀土金属的替代催化剂具有成本低、自然丰度高、全球分布均匀和低毒的特点，对于提高该反应的可持续性至关重要，从而成为氢气的来源。以钴为特征的催化剂是这一反应的极佳候选者，其中对HER析出反应的机理研究已确定关键过程，如COI质子化为CoIII-H物种是形成H-H键的关键中间产物。该项目将开发一系列钴(I)有机金属配合物作为单金属HER催化剂，其中金属中心使用高空间构型的配位体来稳定。这些独特的络合物从未被研究过她的化学，尽管它们具有良好的氧化还原化学和底物结合环境。将研究钴(I)化合物的氧化还原化学和对酸的敏感性，以及它们在HER条件下的电化学反应。从这次调查中获得的信息将使我们能够开发配体设计，以改善反应。学生将受益于合成化学技术(例如，有机金属化学、光谱学、结晶学和动力学研究)和电化学方面的培训。通过光谱、结构和动力学研究确定反应机理，可以优化反应。我们预计这样的研究还将改善放氢所需的反应条件和催化剂负载量。可交付成果-用于HER的新地球丰富的催化剂-对这些反应的机理理解，以及为HER中的催化剂/配体设计提供信息-HER反应的优化

The production of hydrogen through the reduction of water via the Hydrogen Evolution Reaction (HER) is promising sustainable alternative to the use of hydrocarbon feedstocks. The current state of the art uses platinum as it operates at low overpotential with high turnover frequencies. However, the low abundance of platinum (37 ppb in the Earth's crust) leads to high economic and environmental cost, and its high toxicity leads to the production significant waste streams. The use of alternative catalysts featuring earth abundant metals that exhibit low cost, high natural abundance, uniform global distribution and low toxicity is essential to improving the sustainability of this reaction, and therefore as a source of hydrogen. Catalysts featuring cobalt are excellent candidates for this reaction, where mechanistic studies of the HER evolution reaction have identified key processes such as the protonation of CoI to CoIII-H species as key intermediates in the formation of H-H bonds.This project will develop a range of cobalt(I) organometallic complexes as single metal HER catalysts, where the metal centre is stabilised using highly sterically encumbering ligands. These unique complexes have never been investigated for HER chemistry, despite their favourable redox chemistry and substrate binding environment. The cobalt(I) compounds will be investigated for their redox chemistry and sensitivity to acid, along with their electrochemical response in the HER conditions. Information gained from this investigation will allow us to develop the ligand design in order to improve the reaction. The student will benefit from training in synthetic chemical techniques (e.g. organometallic chemistry, spectroscopy, crystallography and kinetic investigations) and electrochemistry. Determination of reaction mechanisms through spectroscopic, structural and kinetic investigations allows the optimisation of the reactions. We anticipate that such investigations will also allow improvements in the reaction conditions and catalyst loadings required for hydrogen release.Deliverables-New earth abundant catalysts for HER-Mechanistic understanding for these reactions, and information to inform catalyst/ligand design in HER-Optimisation of HER reactions