新型(Mo, W)(S, Se, Te)2/石墨烯二维复合热电材料的制备及其性能

Thermoelectric materials, an environmentally friendly clean energy, meet the demand of China’s new energy development strategy with a prosperous application in thermoelectric power generation and refrigeration. Two-dimensional (2D) materials, such as graphene (GE) and transition metal dichalcogenides (MX2, M=Mo, W; X=S, Se, Te), have historically been one of the most extensively studied classes of materials due to the wealth of unusual physicochemical properties. GE and MX2 have high electrical conductivity and thermopower, respectively, and both can be processed in aqueous solution. Owing to their layered nature, atoms are strongly bonded within the same plane but only weakly attached to sheets above and below by van der Waals forces. This weak interlayer interaction makes the extraction of sin¬gle or a few layers of atoms possible, thus leading to the burgeoning research on the thermoelectric property of 2D heterostructures and layered thin films obtained using liquid exfoliation and chemical vapor deposition (CVD) methods. Additionally, the heterostructures of MX2/GE can efficiently decrease the Femi level and thermal conductivity of composite thin-film leading to a better thermoelectric performance. The main objective of this project to construct a singal layered (sl-), a few layered (fl-), or multilayered (ml-) MX2/GE composite thermoelectric thin-film material by spin-coating, filtration, layer-by-layer assembled techniques. The project design desires to adhere to the high conductivity, high carrier mobility and excellent environmental stability of graphene and the unique electronic structure and the high thermopower in order to achieve an effective complementary and enhancement for the 2D layered thermoelectric performance of composite thin-films with a low thermal conductivity. A series of work need to be done such as optimizing the prepared conditions of MX2/GE composite and adjusting the compositions and structures. Additionally, special attentions will be paid to the study on the relation between thermoelectric property and temperature and electron transport, and the ways to improve the thermoelectric property of MX2/GE thin-film, as well as to develop a new method for high performance composite thin-film thermoelectric materials. Accomplishment of this project will provide valuable theoretic foundation and experimental support for the development of novel composite thin-film thermoelectric materials.

热电材料作为环境友好型清洁能源转换材料，符合国家新能源发展重大战略。石墨烯(GE)和过渡金属硫族化物(MX2, M=Mo, W; X=S, Se, Te)是典型的二维(2D)层状材料，分别具有高电导率和热电势，在热电研究领域开始引起重大关注。MX2和GE均可实现溶液处理，易于制备异质结构复合薄膜，其层状结构有利于降低材料的费米能级和热导率，解决单一材料性能(电导率、热电势或热导率)短板所造成的缺陷，从而制备高性能薄膜热电材料。本项目旨在以MX2和GE为主体材料，采用直接剥离和化学气相沉淀等方法及悬涂、抽滤等技术制备新型2D层状异质结构的MX2/GE复合薄膜。通过优化结构和成分，探索其热电性能与结构、组成、温度、电子传输和热传导性能之间的关系。冀望于GE和MX2之间形成有效互补，改善电导率和热电势，降低热导率，提高热电性能，为构筑高性能2D层状无机非金属复合热电薄膜材料提供理论指导。

热电材料作为环境友好型清洁能源转换材料，符合国家新能源发展重大战略需求。二维(2D)层状材料，像石墨烯(GE)和过渡金属硫族化物(MX2, M=Mo, W; X=S, Se)，其层内间原子紧密结合，层层间弱的范德华力，易于制备单层或少层的2D层状异质结构薄膜，并以其独特的物理化学性能，在热电领域引起了广泛关注。本项目旨在以GE和MX2为主体材料，利用各种技术设计和组装单层、少层或多层结构的MX2/GE复合热电薄膜材料。该实验方案设计冀望MX2/GE复合材料能够秉承GE的高电导率、高载流子迁移率和良好的稳定性，以及MX2独特的电子结构和较高的热电势，使GE和MX2之间形成有效互补。. 实验已经顺利完成了单层、少层和多层过渡金属硫化物(Mo, W)(S, Se, Te)2、石墨烯(GE)以及其复合薄膜的制备，并比较全面地研究了(Mo, W)(S, Se, Te)2、(GE)的含量、结构、微观形貌、能带结构以及缺陷等对其薄膜热电性能的影响。本课题选用嵌锂剥离以及溶液超声剥离等方式制备了(Mo, W)(S, Se, Te)2以及(GE)的纳米片，通过对纳米片堆积方式的优化，进而实现对纳米片薄膜热电性能的调控。其次通过将(Mo, W)(S, Se, Te)2纳米片与GE、rGO、PEDOT:PSS等材料复合，制备了多种复合薄膜，并通过对其带隙宽度、缺陷以及基于异质结构下的载流子、声子传输方式的调控，从而实现对薄膜电导率、塞贝克系数以及材料总体热导率的优化；还阐明材料结构与热电性能之间的相关规律，为二维材料在热电领域的潜在应用提供了理论机制。最后，我们还构建了基于石墨烯体系的多种微型热电器件，这些器件制备方法简单，且具有良好的柔韧性、稳定性，较高的电导率、塞贝克系数以及输出功率，有望在未来得到应用。. 在基金资助下，申请人获得2018年度江西省自然科学奖一等奖（排名第一），2016-2019年共计发表SCI论文48篇，申请专利11项(授权3项)，参加国际学术会议14次。

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