基于固相反应可控制备过渡金属硼酸盐材料及其电催化析氧性能研究

As an abundant and clean energy, hydrogen has attracted increasing attention in the past years. Electrochemical water splitting can be considered as one of the promising methods that produce hydrogen. Compared to the hydrogen evolution at cathode, oxygen evolution reaction (OER) at anode shows very slow reaction kinetics because of the involvement of multiproton-coupled electron-transfer steps that build up very high potentials. Therefore, the development of high-efficiency and earth-abundant OER catalysts is crucial. Transition metal borates have been extensively studied in catalytic area due to their unique chemical properties. However, several critical issues are needed to be developed for these kinds of catalysts, like catalytical activity and fabrication method. In this project, we are planning to fabricate transition metal based borate catalysts for oxygen evolution with transition metal and boron containing compounds by solid phase reaction method. Catalytical performance of MBi is planning to be controlled by tuning the material composition and reaction conditions. Bimetallic based borate catalysts will be further prepared through the same way and their catalytic performance and mechanism for OER will also be studied. It will be of great significance to provide a new idea to fabricate efficient electro-catalysts and pave the way to promoting the commercial application of water splitting for hydrogen generation.

氢气的制取是氢能源应用领域的研究热点，通过电解水制备氢气是一种非常有应用前景的方法。然而，电解水的过程一直受到阳极析氧反应动力学的限制，存在很大过电位。因此，开发利用高活性、高稳定性、低成本的电催化剂来降低析氧过电势、提高反应速率是电解水制氢商业化应用的前提。过渡金属硼酸盐化合物因其独特的化学特性在电催化领域引起了广泛的关注。然而，此类催化剂的发展也面临诸多问题，如制备方法急需完善,催化活性有待进一步提高等。针对此类问题，本项目拟采用过渡金属化合物、含硼化合物为原料，利用固相反应技术制备过渡金属硼酸盐析氧催化材料，从原料比例、固相反应条件等方面对产物的组成、结构和性能进行调控。考虑到掺杂对催化剂性能的重要影响，进一步利用固相反应法制备掺杂态二元过渡金属硼酸盐材料，研究其催化析氧反应的性能与机理，以期为制备高效电催化剂提供新的思路，促进电解水制氢的商业化应用。

开发利用高活性、高稳定性、低成本的电催化剂来降低析氧过电势、提高反应速率是电解水制氢商业化应用的前提。过渡金属硼酸盐化合物因其独特的化学特性在电催化领域引起了广泛的关注。本项目以固相反应为基础，采用过渡金属化合物、含硼化合物为原料制备了过渡金属硼酸盐析氧催化材料，从原料比例、固相反应条件等方面对产物的组成、结构和性能进行了调控。考虑到掺杂对催化剂性能的重要影响，进一步利用固相反应法制备掺杂态二元过渡金属硼酸盐材料，如铁原子掺杂镍基金属硼酸盐，研究了其催化析氧反应的性能与机理。研究发现，固相反应法制备的Fe-Ni-B-O催化剂在碱性环境析氧催化性能较好，达到10 mA/cm2 电流密度所需过电位为300 mV，塔法尔斜率较高为315 mV/dec，主要是由硼酸盐化合物中较差的电子传输能力导致的。而过渡金属硼酸盐材料在碱性环境催化析氧反应时会原位转化为金属氢氧化物（MOOH）,有效地提升反应活性，因此其催化活性位点仍为过渡金属氧化物团簇。在电催化领域，我们进一步设计制备了具有异质结构的CoO/Co3O4及具有纳米次级异质结构的CoS/CeO2电催化析氢及析氧催化剂材料，在碱性环境中，电流密度达到10 mA/cm2时所需析氢和析氧过电位分别为108 mV和213 mV，为制备高效电催化剂提供新的思路。过渡金属硼酸盐材料因其多种多样的结构及优异的电化学特性，在储能领域也受到了越来越多的关注，在此基础上我们初步研究了过渡金属硼酸盐材料在储能领域的应用，研究发现，过渡金属硼酸盐材料在碱性环境中，1 A g-1电流密度下的比容量高达655.3 F g-1。当与活性炭材料组成非对称超级电容器之后电压窗口达到1.6 V, 功率密度为1440 W kg-1时能量密度达到103 Wh kg-1，有较好的商业化应用前景。