基于导电硫化物的全水裂解电催化剂的结构设计与性能研究

Electrochemical water splitting is widely considered as a promising and sustainable route for hydrogen production. The overall water splitting process involves two half reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As such, the efficiency of the process is dictated by the overpotentials that have to be applied to overcome the energy barriers inherent to these two half reactions. While there have been some recent reports of alternative, non-noble metal-based catalysts, the catalytic efficiency of most of them is good only for HER or OER (but not both). In addition, the catalytic efficiency of many of them is intrinsically limited by their low electrical conductivity, among other things. Herein, we plan to develop conductive metal sulfide-based, bifunctional electrocatalysts for both HER and OER. We plan to perform a combined theoretical and experimental study for the determination of the catalytic sites for HER and OER. In addition, we plan to meticulously design the microstructures of the newly-developed materials, with the hope that the HER and OER catalytic sites would be optimized simultaneously. Furthermore, we plan to study their catalytic mechanism by careful surface characterization and theoretical simulation. Finally, we plan to construct the conductive sulfide-based water splitting device to achieve a stable and efficient hydrogen production. Our work can be anticipated to give a fresh impetus to the development of water splitting technique.

电催化水裂解是制氢技术中最前沿和最活跃的研究课题之一。水裂解反应包含水还原 (2H+ + 2e– → H2)和水氧化(2H2O → O2 + 4H+ + 4e–)两个半反应, 其能量利用效率由这两个半反应共同决定。针对大多数水裂解催化剂导电性低和只能催化其中一个水裂解半反应的问题，本项目拟以导电硫化物为研究对象，发展高效的双功能全水裂解电催化剂（即能同时催化水裂解两个半反应的催化剂）。在结合理论计算和实验测量进行活性位点认定的基础上，重点通过表/界面结构调控和优化，实现水还原和水氧化活性位点在一个催化材料上的数量和活性的同步提升。利用表面表征技术和理论模拟研究催化剂/水分子界面的微观作用机制和电荷转移、传递行为。构建基于导电硫化物的水裂解器件，进行器件结构优化，实现氢气的高效、稳定输出。可以预期，本项目的实施将对水裂解制氢技术的发展起到积极推动作用。

电催化水裂解是实现绿氢制备的关键技术。水裂解反应包含水还原和水氧化两个半反应，其能量利用效率由这两个半反应共同决定。在本项目的支持下，我们开展了导电硫化物的结构设计与催化性能研究，旨在发挥导电硫化物成本、结构、物理化学性质的优势，开发低成本、长寿命、高活性的水裂解电催化材料。我们已制备了多例导电硫化物水裂解催化剂，并系统地研究了这些材料的水裂解催化性能，初步阐明了催化剂微观结构与催化性能之间的内在关系，所研制的硫化物催化材料在工业器件条件下展示了优异的催化性能。已发表SCI论文15篇（1篇Chem、1篇Nature communications、3篇Angewandte Chemie International Edition、1篇Advanced Energy Materials、1篇Energy & Environmental Science、4篇Chemical Communications、2篇Inorganic Chemistry Frontiers、1篇Chemical Engineering Journal、1篇 Scientific reports），4项中国发明专利获授权。项目期间取得的主要研究进展包括：1、合成了含Fe-Fe金属键的四方硫铁矿相FeS双功能“前”电催化剂，并详细研究了FeS在催化过程中的结构演化，并构建了基于Fe-S衍生催化剂的电解池，其性能优于IrOx||Pt/C组合的电解池。2、开发了超快速（5 s）界面反应策略，实现了导电硫化物表面双金属氢氧化物薄膜的均匀修饰，所得复合材料可在大电流密度下保持高效稳定催化水分解。3、提出了一种室温表面硫化处理不锈钢网/镍网的方法，可实现平方米级电极的一次性制备，基于该电极组装的电解池性能可媲美商业雷尼镍电极。