多力场耦合剥离天然辉钼矿制备寡层MoS2纳米片机制及其多级复合纳米材料设计与功能调控

Synthesis of high-performance materials directly from natural minerals is an efficient way to achieve a low-carbon economy. Molybdenite is abundant in China. To surmount the key challenges in transforming molybdenite to high-value materials is of great significance not only in promoting interdisciplinary integration of minerals engineering and materials science, but also in accelerating sustainably fine development of molybdenum mining. Molybdenite, consisting of the layered-structure MoS2 compound, can be exfoliated to few-layer MoS2 nanosheets (FL-MoS2 NSs) that are widely used in catalysts, energy storage, sensors, electronics and other fields. Aiming at low exfoliation efficiency, poor performance and other problems, this project develops a new strategy to exfoliate natural molybdenite to FL-MoS2 NSs via novel multi-fields coupling processes, e.g., "sanding–ultrasonic cavitation" and "cutting–ultrasound cavitation" in environmentally friendly media of alcohol/water mixtures and supercritical CO2 fluid, benefiting from the synergistic effect of the specific solvents and multi-fields coupling to improve the exfoliating efficiency. The as-obtained FL-MoS2 NSs are then to be used as the substrates to hybridize, anchor or assemble some second-phase nanocrystals (e.g., metal clusters, semiconductor quantum dots, graphene, carbon dots, and so on) to construct hierarchical nanocomposites, according to the function-oriented principle; the functional behaviors of the hierarchical nanocomposites obtained are to be systematically investigated as hydrogen-evolution catalysts, LIB electrode materials, gas-sensing active materials and so on. The research emphases will be focused on seeking for influencing factors and mechanisms of the exfoliation of molybdenite via the multi-fields coupling strategy, and on understanding the structure-functionality relationship laws and the regulating measures of the FL-MoS2 NSs based hierarchical nanocomposites as energy and environmental active materials. Innovation and features of this project lie in exfoliating natural molybdenite by multi-fields coupling processes to form FL-MoS2 NSs based functional nanocomposites. Implementation of this project will be helpful in deepening the understanding of exfoliation mechanisms of layered minerals, and promoting the crossing disciplinary development of mineral processing and materials science, and will also provide theoretical and technical supports in the applications of molybdenite as new energy-storage and environmental materials.

由天然矿物直接制高性能材料是发展低碳经济的有效途径。我国辉钼矿储量大，攻克辉钼矿材料化利用科技难题意义重大。以层状MoS2为组成的辉钼矿可剥离成寡层MoS2纳米片，在催化、传感、储能中应用广泛。针对剥离效率与性价比低等问题，项目提出以天然辉钼矿为原料，以醇/水、超临界CO2等为介质，利用“砂磨-超声”、“剪切-超声”等多力场耦合剥离辉钼矿，制备寡层MoS2纳米片，藉溶剂与多力场耦合的协同效应，提高剥离效率；以所得MoS2片为基体，依功能导向原则锚固、组装金属簇、半导体量子点或石墨烯等第二相纳米晶，制备多级复合纳米晶，并研究催化产氢、锂电储能、气敏传感等性能；重点研究辉钼矿多场耦合剥离的影响因素与机制，探寻MoS2基复合材料的构效规律与性能调控措施。创新特色在于多力场耦合剥离天然辉钼矿制寡层MoS2纳米片基复合材料，为理解层状固体剥离机制、促进辉钼矿到新能源材料应用提供理论依据与技术方案。

层状纳米材料具有二维特特殊结构，在电子传输、光电催化等方面具有独特优势。原子沉积等自下而上生长二维纳米材料的方法存在效率低、难量产等困难。该项目以天然层状矿物为原料，提出了“超声”、“砂磨”、“剪切”、“超临界”等多力场联用剥离的新思路，在CO2超临界、醇/水、NMP等试剂中，综合利用超声空化与剪切、挤压作用，将层状固体剥离成二维纳米片，具有高效、层片结构完整、分散性好等优势。试制了多力场剥离装置，并以辉钼矿、鳞片石墨等典型层状矿物为例子，系统研究了多力场剥离的影响因素（原料预处理、溶剂种类、剥离助剂、超声功率、砂磨转速、超临界参数）与剥离机制。在NMP中超声-砂磨剥离辉钼矿制备MoS2纳米片的产率达30%，厚度均匀且为2纳米左右，层面有许多孔洞，可提高MoS2纳米片的边界及基面原子催化活性。在超声-剪切-超临界系统中剥离鳞片石墨制得了厚度为5~6纳米石墨烯（产率30%以上），在储能、防腐涂料等领域有重要应用。将超声-砂磨作用与传统生物质炭两步制备法相结合，以价廉量丰的玉米芯为原料，制得了高纯、高比表面积、微/介孔比例可控的生物质炭材料，在超级电容、重金属离子/染料分子吸附等应用中的性能远超最好商用产品。系统研究了层状钼酸在KCl水溶液中超声剥离形成氧化钼微纳米棒的作用机制及储能性能。同时，作为拓展内容，系统研究了微波熔盐快速制备类石墨相氮化碳产氢催化剂，发现微波熔盐在K+掺杂、三嗪基/七嗪基比例调控中起关键作用，大幅提高了类石墨相氮化碳光催化产氢性能与制备效率。此外，以石墨烯、MoS2、WO3、碳纳米管等1D/2D纳米结构为基底，原位生长SnO2、CuO、ZnO等纳米颗粒，构筑了系列多级结构复合纳米材料，在有害气体传感检测方面具有显著提高的低温选择性响应特性。综上，项目在层状固体高效剥离、低维多级纳米结构构筑等方面的创新性结果对纳米材料学科及其产业应用具有较大的促进作用。