光电化学-反电渗析联用制氢系统及氧化亚铜-硫化钼/石墨烯-二氧化钛高效多层光电极的开发与应用

Photoelectrochemical (PEC) water splitting has attracted great interest as an effective way of converting sunlight into chemical energy in the form of hydrogen, which is a clean alternative to fossil fuels. In this project, we will design a new hydrogen production system by coupling the PEC with a reversed electrodialysis cell (REC). In this new integrated system (P-REC), the REC can transform the salinity gradient energy into electricity, and provide a bias for the PEC. This bias can help increase the charge separation efficiency and overcome the overpotential associated with the hydrogen production. Furthermore, with the help of PEC, the REC stack can decrease its cell pairs for this application, which is beneficial for decrease its ohmic resistance, reducing cost and energy loss. To increase the efficiency of P-REC further, a new kind of photocathode with a muti-layer structure will be prepared. In this photocathode, the cuprous oxide (Cu2O) was prepared by electro-deposited method on fluorine doped tin oxide glass (FTO) glass and was used as the main body. The out-layer of the photocathode is titanium dioxide (TiO2), which will be used a protective layer to increase its anti photo-corrosion property. The addition of TiO2 layer can also form a p-n junction structure with Cu2O to increase its activity further. The Molybdenum disulfide (MoS2) and graphene (GR) hybrid was synthesized and used as the inner layer cocatalyst for the further modification of the photocathode. GR here was used as electron transfer highway due to its excellent electron conductivity, and MoS2 was served as electron collectors. The presence of them is beneficial for the interfacial electron transfer and thus enhance the separation of the photo-generated electron-hole pairs. Thus, this unique type of integrated system with this new kind of effective photocathode has significant potential to produce pure H2 gas without any consumption of electrical grid energy, and provide a new choice for solving the energy problem.

光电化学电解池（PEC）产氢可以将太阳能转化为电能来制备氢气，在解决能源问题方面有很大的潜力。本项目拟设计PEC与反电渗析电池（REC）联合产氢系统（P-REC），利用REC将盐差能转化为电能并作为PEC的偏压，用于克服PEC产氢过程中的电极过电位，并促使光电子定向移动，促进空穴-电子的分离，提高太阳能的利用效率。PEC与REC产生的电压互补，可以减少REC的交换膜对数，减小系统内阻、设备成本和盐差能损失。该项目还将制备高效光电极用于P-REC中作为光阴极，电极主体为催化性能高的可见光敏感的氧化亚铜（Cu2O），夹层助催化剂为硫化钼与石墨烯的复合物，其良好的电学性能可以促进光电子与空穴的分离，提高主体催化剂的活性，外层保护层为二氧化钛（TiO2），不仅可以增加其抗光腐蚀性，还可以与Cu2O形成p-n结，进一步提高光电极的光电催化活性。该项目的研究成果将为解决能源问题提供一个新的选择。

能源短缺是二十一世纪面临的严峻问题，寻找可持续以及清洁的能源不仅能够解决由能源短缺引发的各种社会问题，还可以减少由化石燃料燃烧导致的环境污染。氢气作为清洁的可再生能源，具有高燃烧值（是一般化石燃料的三倍）、零污染物排放、零温室气体排放和可循环利用等优点，可以较好的解决上述能源问题。光电化学电解池（Photoelectrochemical cells, PEC）产氢技术是一项新兴的能源技术，可以将太阳能转化为电能并用来制备氢气，具有很大的发展潜力。反电渗析技术（Reversed electrodialysis cells, REC）能够将盐差能转化为电能，如果能够利用该电能为PEC系统提供偏压来提高其光电转换以及产氢效率，将对两种能源的开发利用都起到积极的促进作用。.本项目旨在制备多层复合物薄膜光电极并用于光电催化制备氢气，并研究硫化钼和石墨烯等材料作为助催化剂对光电极活性的影响。在此基础上开发光电化学电解池（PEC）与反电渗析电池（REC）联用装置（P-REC），以反电渗析过程产生的电压作为PEC系统的偏压来实现高效的催化产氢过程。（1）我们以石墨烯和硫化钼为基础合成了具有很高电催化活性的析氢催化剂，并研究了石墨烯的多孔化以及硫化钼的形貌、相态对其电催化活性的影响。通过本项目的相关实验，我们证实石墨烯经过氮硫双掺杂以后，其可以作为有效的光催化助剂，提高其光催化产氢性能；石墨烯和硫化钼复合以后具有很高的电析氢催化活性，且不含贵金属，成本较低，在一定程度上可以作为贵金属的替代品用于析氢反应（2）氧化亚铜光电极采用分层组装的形式，通过添加保护层和析氢催化剂层可以大幅度提高其稳定性和光电析氢活性。（3）将反电渗析和光电催化结合，以反电渗析过程产生电压为光电过程提供过电位，可以提高两种能源的利用率和产氢效率。.通过本项目的研究工作，我们获得了多种非贵金属的电析氢催化剂以及高效的光电极，为电析氢以及光电析氢过程提供了低成本高效的可行性解决方案。