Electrocatalytic Cross-Coupling Reactions with Heterogeneous Single Atom Catalysts

精细化学品占全球化学品市场的最大份额，到2024年，其收入预计将增长到2200亿美元。精细化学品的重要类别包括药品、农用化学品、香料和香料以及特殊材料（如聚合物）。随着人们对能源利用、环境影响和安全问题的日益关注，迫切需要开发新的、温和的、高效的合成工艺来实现精细化学品的可持续合成。随着研究人员探索如何利用电作为试剂来合成精细化学品，电化学催化有了显著的复兴。这些节能、电力驱动的过程可以很容易地与可再生能源相结合，避免使用危险和有毒化学品，这使它们成为化学合成的强大绿色工具。然而，目前，电催化方法通常使用所谓的均相催化系统，这需要过渡金属催化剂，其中所有的催化剂都完全溶解在反应混合物中。由于这些体系在反应条件下的稳定性有限，因此往往需要高催化剂负载。此外，由于催化剂分离和回收方面的挑战，昂贵的均相催化剂只能使用一次。随着纳米科学的快速发展，非均相催化剂已被用于解决上述问题。虽然它们稳定且方便回收，但它们的整体催化效率通常不如同质的同类。近年来，一类新的非均相催化剂即单原子催化剂（SACs）正在成为催化科学研究的新前沿。在这种情况下，催化剂的活性金属中心作为孤立的单原子存在，由支撑材料稳定。SACs可以作为均相催化剂和非均相催化剂之间的桥梁，可以综合两种催化剂的优点，如高活性、选择性、稳定性和可重复使用。事实上，最近在使用SACs的清洁能源转化反应（如氧还原、析氢、CO2还原）方面取得了许多突破。这些材料在电化学应用中显示出巨大的潜力，但利用SACs进行电催化精细化学合成仍未被探索。交叉偶联反应作为药物合成中最常用的一类反应，于2010年获得诺贝尔化学奖。在这个项目中，我们将利用SACs的固有特性，通过创造全新的非均相电化学交叉偶联反应来彻底改变精细化学合成，作为概念验证的例子。通过与大连化学物理研究所黄延强教授（DICP， SACs概念的诞生地），Karl Ryder教授（UoL）和MOF Technologies的最新合作，新型镍基SACs将以金属有机框架（MOF）为前驱体合成。这些SACs催化反应的机制将使用现代材料表征技术进行研究。该项目是高度跨学科的，是前沿有机合成、电化学、材料科学和最先进的多相催化的交叉点。该领域的成功将带来经济和环境效益，并使精细化学品（如药品）的生产能够采用更可持续的工艺。对催化剂结构-性能关系和反应机制的理解将使新的sac系统的设计成为可能，这些系统可以用于一系列化学反应，扩大其影响。

Fine chemicals make up the largest portion of the global chemicals market with their revenues expected to grow to $220bn by 2024. Examples of important classes of fine chemicals, are pharmaceuticals, agrochemicals, flavours and fragrances and speciality materials (e.g., polymers). With the increasing attention on energy usage, environmental impact and safety, there is an urgent need to develop new, mild and efficient synthetic process for sustainable fine chemicals synthesis. There has been a remarkable renaissance of electrochemical catalysis, with researchers exploring how fine chemicals can be synthesised with using electrictricity as a reagent. These energy efficient, electricity-driven processes can be easily integrated with renewable energy sources and avoid the use of dangerous and toxic chemicals, which makes them a powerful green tool for chemical synthesis. However, at present, electrocatalytic methods typically utilise so called homogeneous catalytic systems, which requires transition metal catalysts, whereby all of the catalyst is fully dissolved in the reaction mixtures. These systems often suffer from high catalyst loadings due to their limited stability under the reaction conditions. Furthermore, the expensive homogeneous catalyst can only be used once due to the challenges associated with catalyst separation and recycling. With the rapid growth of nanoscience, heterogeneous catalysts have been exploited to tackle the aforementioned problems. Although they are stable and conveniently recyclable, their overall catalytic efficiencies are usually inferior to their homogeneous counterparts. In recent years, a new class of heterogeneous catalysts, namely single-atom catalysts (SACs), which are emerging as a new frontier in catalysis science. In this case, the active metal centre of the catalyst exists as isolated single atoms, which are stabilized by the support material., SACs can serve as a bridge between homogeneous and heterogeneous catalysts with the possibility of integrating the merits of both types of catalysts such as high activity, selectivity, stability and reusability. Indeed, many breakthroughs in clean energy conversion reactions (e.g., oxygen reduction, hydrogen evolution, CO2 reduction) using SACs has been reported recently. These have demonstrated their great potential in electrochemical applications, but electrocatalytic fine chemical synthesis using SACs remains unexplored. As the most frequently used class of reaction in pharmaceutical synthesis, the so called cross-coupling reactions were recognized in 2010 by the Nobel Prize in Chemistry. In this project, we will exploit the inherent properties of SACs to revolutionise fine chemical synthesis by creating completely new heterogeneous electrochemical cross-coupling reactions as proof-of-concept examples. Through newly forged collaborations with Prof. Yanqiang Huang from Dalian Institute of Chemical Physics (DICP, the birthplace of SACs concept), Prof. Karl Ryder (UoL) and MOF Technologies, novel nickel based SACs will be synthesized using metal organic frameworks (MOFs) as precursors, and the mechanisms of these SACs catalysed reactions will be studied using modern material characterization techniques This project is highly interdisciplinary and at the intersection of cutting-edge organic synthesis, electrochemistry, materials science and state-of-the-art heterogeneous catalysis. Success in the area will bring both economic and environmental benefits and enable the manufacture of fine chemicals, such as pharmaceuticals, to be prepared using more sustainable processes. The understanding of catalyst structure-performance relationships and reaction mechanisms will enable the design of new SACs systems, that can be exploited for a range of chemical reactions, broadening its impact.