铁钴镍金属硫硒磷化物的掺杂与复合及其作为析氢/析氧双功能电催化剂的全分解水性能研究

Electrocatalytic water splitting is the the most promising approach to hydrogen production, however, the high energy comsumption and the high cost of noble-metal electrocatalysts greatly hinder its practical application. Developing highly efficient noble-metal-free electrocatalysts is the key issue in the field of water electrolysis. In this project, we aim at preparing “doped-type” and “interfacial-type” bifunctional electrocatalysts that are composed of first-row Group VIII metal (iron, cobalt, and nickel) sulfides, selenides and phosphides to improve the activity toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). For the “doped-type” bifunctional electrocatalysts, the doping process can modulate the composition, chemical environment and electronic structure of the catalytic active sites, and then influences the adsorption-desorption energy of the H-, OH- and H2O on the active sites, resulting in the changing of the activity for HER and OER. While for the “interfacial-type” bifunctional electrocatalysts, an HER-active phase and an OER-active phase is used to construct an interface by forming composites to efficiently realize both HER and OER. On the basis of the above ideas, we will develop and optimize methods for the preparation of the “doped-type” and “interfacial-type” bifunctional electrocatalysts, which are composed of first-row Group VIII metal sulfides, selenides and phosphides. We will illustrate the effect of the doping and interface-forming processes on the composition, chemical environment and electronic structure of the catalytic active sites, and reveal the structure-function relationship between active sites and HER and OER activity. We will explore the correlative and interacting dependence of HER on OER and vice versa, and develop methods for the collaboratively optimizing both HER and OER activities, and then realize highly-efficient electrocatalytic overall water splitting. We hope the results of this project can shed light on the development of electrocatalyst systems with novel structure, high energy conversion efficiency and low cost.

高能耗及贵金属催化剂的高成本制约了电解水的实际应用。发展非贵金属基的电解水催化剂是该领域的重要课题。本项目基于铁钴镍的硫化物、硒化物和磷化物(硫硒磷化物)，通过制备“掺杂型”和“相界面型”的析氢/析氧双功能电催化剂，协同提高析氢析氧电催化活性。掺杂型双功能电催化剂通过元素掺杂调控金属硫硒磷化物的表面化学组成和电子结构，影响析氢析氧过程的关键吸脱附步骤，进而影响析氢析氧催化活性。相界面型双功能电催化剂基于析氢和析氧的优势表面，通过构筑两相界面，实现同时析氢、析氧电催化反应。基于以上思路，本项目拟建立和完善“掺杂型”和“相界面型”析氢/析氧双功能电催化剂的制备方法；揭示掺杂和相界面对催化活性中心化学环境和电子结构的影响及其与析氢析氧催化活性的构效关系，阐明双功能催化剂的析氢析氧催化活性之间的相互依赖及制约关系，发展协同优化方法。为新型、高效、低成本电解水催化剂体系的设计和研制提供新的思路。

发展非贵金属基的析氢、析氧电催化剂是电催化分解水该领域的重要课题。本项目基于铁钴镍的硫化物、硒化物、氧化物及氢氧化氧化物，通过制备“掺杂型”和“相界面型”的析氢、析氧电催化剂，提高析氢析氧电催化活性，开发高效双功能电催化剂。主要研究内容包括：研究“掺杂型”和“相界面型”析氢、析氧电催化剂及双功能电催化剂的制备方法；揭示掺杂和相界面对催化活性中心化学环境和电子结构的影响及其与析氢析氧催化活性的构效关系，研究双功能催化剂的析氢、析氧催化活性协同优化方法，实现高效、低成本电催化分解水。.主要研究结果如下：（1）建立并完善了基于Fe, Co, Ni硫硒化物、氧化物的制备及掺杂方法，成功制备出多种高效的“掺杂型”析氢、析氧电催化剂，如：S-CoSe2、S-Ni3Se4、Se-Ni3S2、S-Ni3Se4/Se-Ni3S2析氢电催化剂，Ir-CoPi、Cr-NiCo2O4析氧电催化剂；结合DFT计算及电化学表征阐明了掺杂原子对催化活性中心电子结构的影响及其对氢离子、氢氧根及水分子吸脱附能量的影响规律，揭示了掺杂型电催化剂的结构与其催化活性的的构效关系。（2）发展出基于两种Fe、Co、Ni基金属硫硒化物、氧化物的“相界面型”电催化剂的制备方法，成功制备出多种相界面型电催化剂，如S-Ni3Se4/Se-Ni3S2、NiSx-WO2.9析氢电催化剂，FeOOH/Cr-NiCo2O4析氢、析氧双功能电催化剂等；揭示了相界面这一特殊结构的化学组成、相组成及电子结构分别对析氢、析氧反应的影响规律；阐明相界面在电催化析氢、析氧过程中的作用。（3）基于NiOOH及NiFeOOH电催化剂，发现相同组成的催化剂中相结构对催化活性有重要影响，揭示了相结构影响催化活性的机理。（4）发展出可靠的测定电催化剂析氢、析氧反应活化能的方法，成功测定了多种电催化剂的析氧反应活化能，为推测反应历程及机理提供了实验依据。（5）揭示了双功能催化剂的析氢、析氧催化活性之间的相互依赖及制约关系，发展了双功能电催化剂析氢、析氧催化活性的协同优化方法，基于双功能催化剂FeOOH/Cr-NiCo2O4实现了高效的电催化全分解水。本项目的研究结果为新型、高效、低成本电催化体系的设计和研制提供新的思路。