|Alternative Title||Preparation and Electrocatalytic Performance of Molybdenum Disulfide Based Hybrid Electrode for Electrochemical Overall Water Splitting|
|Place of Conferral||兰州|
|Keyword||MoS2 Ni3S2 WS2 FeOOH NiOOH HER OER 全水分解|
随着传统化石燃料的逐步消耗，能源短缺和环境污染问题变得日益严峻。因此，发展经济高效和可持续的绿色能源显得尤为迫切。氢能具有高能量转换效率、清洁可再生等优点，被认为是一种非常有应用潜力的理想绿色能源，而电催化分解水是非常有效的产氢方式之一。目前，析氢反应(HER)和析氧反应(OER)性能最好的催化剂仍然是一些铂基金属和铱、钌金属氧化物等贵金属材料，但是它们稀缺的储量、高昂的成本以及较差的稳定性严重制约了其大规模商业化应用。因此，大多数的研究者们将目光聚焦在寻找和制备价格低廉、高效稳定以及无污染的非贵金属催化剂材料上。二硫化钼(MoS2)因其储量大、催化性能较好和对环境友好等的特点而被广泛研究。但是，其在碱性条件下的催化析氢和析氧性能还有待提高。因此，本论文从杂原子掺杂、耦合界面入手，构筑了系列MoS2基电催化剂，对其电催化水分解性能进行了详细系统的研究。主要研究内容与实验结果如下：1. 采用温和的一步水热法在3D泡沫镍基体上制备出钨掺杂的MoS2@Ni3S2 (Mo(1-x)WxS2@Ni3S2)杂化电极，并系统地考察了该电极的电催化HER和OER性能。结果表明所制备的Mo(1-x)WxS2@Ni3S2杂化电极只需98和285 mV的HER和OER过电位即可达到10 mA cm-2的电流密度，其水分解电压也只有1.62 V。该电极优异的电催化性能可归结于W的掺杂有效地调控了MoS2的电子结构。因此，Mo(1-x)WxS2@Ni3S2电极的成功制备为设计高效稳定的全水分解双功能催化剂提供了新的研究思路。2. 通过水热与溶剂热法相结合的技术制备出NiOOH修饰的MoS2@Ni3S2 (MoS2@Ni3S2 NWs-NF/NiOOH)杂化电极，并将其应用于电催化水分解领域中。实验结果表明NiOOH与MoS2@Ni3S2的复合有利于电极材料导电性的提高，二者的协同作用明显地提高了电极催化活性。在电流密度为10 mA cm-2时，MoS2@Ni3S2 NWs-NF/NiOOH电极的HER和OER过电位分别为101和266 mV，全水分解电压则为1.60 V。此实验为设计与制备高性能的双功能电催化剂提供了新的方向。3. 利用水热法与恒电流电沉积相结合的技术合成出FeOOH修饰的MoS2@Ni3S2 (MoS2@Ni3S2 NWs-NF/FeOOH)杂化电极，并系统地研究了该复合电极的电催化性质。实验结果表明，在电流密度为10 mA cm-2时，MoS2@Ni3S2 NWs-NF/FeOOH电极的HER和OER过电位分别为95和234 mV，全水分解电压也仅有1.57 V。此外，密度泛函理论(DFT)计算表明耦合界面的存在有效地优化了H和含氧中间体的化学吸附能，促进了HER和OER过程。因此，这项工作标志着在开发具有高成本效益的全水分解催化材料方面迈出了重要的一步。
The problems of energy shortage and environmental pollution become increasingly severe with the gradual consumption of fossil fuels. Therefore, it is particularly urgent to develop efficient, cost-effective and sustainable green energy. Hydrogen has been recognized as one of the most promising green energy source due to the advantages of high energy conversion efficiency, clean and renewable. Electrocatalytic water splitting is one of the most effective ways of hydrogen production. At present, Pt-based metal and Ru, Ir-based metal oxide still are the state-of-the-art electrocatalysts to drive HER and OER, respectively. However, the large-scale commercial applications of noble metal materials are severely restricted by their scarce reserves, high cost and poor stability. As a result, most researchers focus on searching and preparing non-precious metal catalyst materials with characteristics of low-cost, high-efficiency and contamination free. Molybdenum disulfide (MoS2) has been widely studied due to its large reserves, good catalytic performance and environment-friendly. However, its catalytic performance for hydrogen evolution and oxygen evolution under alkaline conditions remains to be improved. Therefore, in this paper, a series of MoS2 based electrocatalysts are constructed from the doping of heteroatom and the coupling interface and the performance of electrocatalytic overwall water splitting has been systematically studied. The main research contents and experimental results are as follows:
1. Tungsten doped MoS2@Ni3S2 (Mo(1-x)WxS2@Ni3S2) hybrid electrode was prepared on 3D nickel foam substrate by a facile one-step hydrothermal method, and its electrocatalytic properties of HER and OER were systematically investigated. The results show that only 98 and 285 mV for HER and OER overpotentials were needed to acquire the current density of 10 mA cm-2 for the Mo(1-x)WxS2@Ni3S2 hybrid electrode, and its overall water splitting voltage was merely 1.62 V. The excellent electrocatalytic properties of the electrode can be attributed to the W doping effectively regulates the electronic structure of MoS2. Therefore, the successful preparation of Mo(1-x)WxS2@Ni3S2 hybrid electrode provides a new research idea for the design of high efficient and stable overall water splitting bifunctional catalysts.
2. The NiOOH modified MoS2@Ni3S2 (MoS2@Ni3S2 NWs-NF/NiOOH) hybrid electrode was prepared by the combination of hydrothermal and solvothermal method, and it was applied to the field of electrocatalytic water splitting. The experimental results show that the combination of NiOOH and MoS2@Ni3S2 is conductive to the improvement of the conductivity of the electrode materials. The synergistic effects originated from the coupled interfaces of the catalysts obviously improves the catalytic activity of the electrode. Only 101 and 266 mV are needed to drive the current density of 10 mA cm-2 for HER and OER of MoS2@Ni3S2 NWs-NF/NiOOH electrode, respectively, and the overall water splitting voltage is 1.60 V. This experiment provides a new direction for the design and preparation of high-performance bifunctional electrocatalysts.
3. The FeOOH modified MoS2@Ni3S2 (MoS2@Ni3S2 NWs-NF/FeOOH) hybrid electrode was synthesized by the combination of hydrothermal method and the galvanostatic electrodeposition, and the electrocatalytic properties of the electrode were studied systematically. The experimental results show that when the current density is 10 mA cm-2, the HER and OER overpotentials of the MoS2@Ni3S2 NWs-NF/FeOOH electrode are 95 and 234 mV, respectively, and the overall water splitting voltage is only 1.57 V. In addition, density functional theory (DFT) calculation indicates that the existence of the coupling interface effectively optimizes the chemisorption energy of H and oxygen intermediates, hence promotes the HER and OER processes. Therefore, this work marks an important step in developing cost-effective catalytic decomposition materials.
|郑美勇. 二硫化钼基复合电极的制备与电催化水分解性能研究[D]. 兰州. 兰州大学,2018.|
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