镍基层状双氢氧化物超晶格复合材料的制备及电催化水分解性能研究

Splitting water into hydrogen gas is a novel route to relax energy crisis and climate change problem originating from the consumption of fossil source. Nonetheless, the speed of water splitting is limited by the water oxidation process. So, development of efficient and stable water oxidation catalysts is important and desirable for total water splitting. Nickel based layered double hydroxides (LDHs) (Ni-Fe, Ni-Co, Ni-Mn) have received extensive attention because of the unique two-dimensional layered structure and high-catalytic efficiency for catalytic water oxidation. Nevertheless, the low electrochemical stability and conductibility of LDH nanomaterial have embarrassed the implication in the electrocatalysis field. This project focuses on developing novel electro-catalytic materials. The efficient superlattice electrocatalysts will be synthesized via hybridizing of exfoliated LDH nanosheets and Graphene MoS2, WS2 with high conductivity and electrochemical stability through electrostatic interaction at molecular scale. Then, the catalytic activities of as-synthesized nickel based LDH nanosheets hybrid catalysts for the water splitting will be tested. The relationship between structures, elements of the catalysts and their catalytic activities will be investigated using different test facility. This work will be expected to promote our scientific level on the preparation and self-assembly of layered nanomaterial, and it is significant to advance the development of new energy materials.

利用高效催化剂电解水制备氢气是一种缓解能源危机和环境污染的新途径，然而，水分解制氢速率主要受到水氧化过程的限制。因此，发展高效、稳定水氧化催化剂是实现快速水分解的关键，镍基层状双氢氧化物（Ni-Fe，Ni-Co，Ni-Mn）纳米材料由于独特的二维层状结构以及较高的水氧化催化活性受到了广泛的关注。但是，镍基氢氧化物电导率低、电化学稳定性差，限制了其在能源转化领域的应用。本申请拟利用单层镍基氢氧化物纳米片与具有较高电导率和电化学稳定性的石墨烯、MoS2、WS2纳米片通过静电作用分子尺度组装，制备高效、稳定电解水催化剂。对镍基催化剂进行性能测试，并利用各种表征技术研究催化剂组成和结构与其催化性能之间的内在联系，建立催化剂的构-效关系模型，为设计高效水分解催化复合材料提供理论和实验基础。该工作有助于提高层状复合材料的制备与组装领域水平，同时推动新能源材料快速发展，具有重要的理论和现实意义。

氢气作为一种绿色能源，广泛应用于石油化工、燃料电池、航空航天领域。传统工业制备氢气技术制备氢气含有痕量杂原子，严重影响了氢气在能源存储和转化领域的应用。电解水生成氢气是制备高纯氢气的有效途径，但是电解水过程过电位高、电化学稳定性差仍是阻碍催化剂应用的主要因素。因此，开发具有储量高、价格低、催化效率高的电解水催化剂是解决这一问题的关键。本项目主要利用具有寡层结构的石墨碳与过渡金属化合物原位复合构筑具有超晶格结构/多级结构的复合材料，并研究其表界面结构对催化过程的影响。通过增加催化剂比表面积提高其活性位点数量，加速电解水过程。另外，通过降低石墨碳厚度加速了电荷的迁移速率，同时，碳材料中氮原子的掺入加速了对OH-的吸附。另外，通过调控催化剂中Ni和Fe的组份，调控对对中间体*OOH的形成速率，从而为催化剂的制备提供实验基础。本项目通过上述对催化剂结构、组成以及催化过程研究，明晰电催化过程电解质迁移、电荷传导与催化剂结构关系，从而理清催化剂“构-效”关系的内在关联机制。