原子级精确多孔二维超四面体锡氧硫族簇基纳米片的制备及其电催化二氧化碳还原性能的研究

Two-dimensional nanomaterials have broad applications due to their unique structure. However, in the field of electrocatalysis, two-dimensional nanomaterials still face some problems, such as the significant reduction of the electrochemical active area caused by the re stacking, the inherent defects/vacancies and heteroatom doping in the preparation process of materials that make it difficult for people to directly know the exact structural information and coordination environment of specific active sites. On the other hand, tin-based materials, which are nontoxic and abundant in reserves, are one of the most widely studied materials for electrocatalytic reduction of CO2. In this project, the crystal of two-dimentional supertetrahedral Tin oxychalcogenide cluster-based compound with accurate structure is used as the precursor to prepare atomically precise holey two-dimentional supertetrahedral Tin oxychalcogenide cluster-based nanosheet by cation exchange-assisted liquid exfoliation under suitable conditions, and used as a special structure model to study its performance of electrocatalytic reduction of CO2 in depth. This project will not only help to figure out the catalytic active sites and mechanism of tin-based materials from the microscale of atomically precise nanoclusters, lay a foundation for the design of highly efficient electrocatalysts for CO2 reduction, but also help to develop a new kind of cluster-based two-dimensional nanomaterials, and also to provide new materials and technical guidance for the related research fields, such as photoelectric devices, photo/electro-catalysis, lithium sulfur batteries and spin electronic devices.

二维纳米材料以其独特的结构具有广泛的应用前景。但在电催化领域，二维纳米材料仍面临着诸如重新堆积导致材料电化学活性面积显著降低，材料制备过程中固有缺陷/空位以及异原子掺杂使人们很难直观获悉特定活性位点的精确结构信息和配位环境等问题。另一方面，无毒且储量丰富的锡基材料是目前主族金属中研究最广泛的电催化二氧化碳还原材料之一。本项目以结构精确可知的二维超四面体锡氧硫族簇基化合物晶体为前驱体，旨在通过阳离子辅助溶液剥离法在合适条件下制备原子级精确多孔二维超四面体锡氧硫族簇基纳米片，并将其作为一类特殊的结构模型，深入研究其电催化二氧化碳还原性能。此项目不仅有助于从分子团簇微观尺度上探明锡基材料的催化活性位点和催化机理，为设计高效二氧化碳还原电催化剂奠定基础，同时有助于拓展一类新型簇基二维纳米材料，为光电器件、光/电催化、锂硫电池和自旋电子器件等相关领域的研究提供新型材料和技术指导。

二维纳米材料以其独特的结构在电催化领域具有广泛的应用前景，但其材料制备过程中固有缺陷/空位使人们很难直观获悉特定活性位点的精确结构信息和配位环境等问题。另一方面，无毒且储量丰富的锡基材料是目前主族金属中研究最广泛的电催化二氧化碳还原材料之一,而其主要产物甲酸是一种高附加值原料。本项目以结构精确可知的二维超四面体锡氧硫族簇基化合物晶体为前驱体，通过Li离子插层辅助超声溶液剥离法在温和条件下制备了一种原子级精确二维超四面体锡氧硫簇基超薄纳米片，并将其与石墨烯静电自组装复合，深入研究了其电催化二氧化碳还原性能。AFM和TEM表征可知该纳米片具有超薄的厚度（~3.3 nm）和均匀的纳米孔。电化学研究表明，所制备的T3-SnOS NSs/PDDA-GR复合物具有较好的电催化二氧化碳产甲酸盐性能，其法拉第效率在-0.8 V电位大于85 %，同时其具有较长时间的稳定性（24 h）。通过对比其他两种锡硫簇基纳米片，T3-SnOS NSs由于其独特的“Sn-O/Sn-S核壳结构”及其表面丰富孔洞的协同效应，因而具有高效CO2RR催化活性。同时在本项目的资助下，将带负电的离散多金属P2硫化物团簇和带正电的碳纳米管静电自组装，构筑了一种新型0D/1D异质结构。由于P2硫化物团簇含有Cu、Ga、In 和 Sn 四种金属成分，且Ga、In组分比例可调控，由此制备的异质结构可以高效的将CO2电化学还原为C1产物(CO+HCOOH)，并具有高的法拉第效率 (FE) (>80%)和TOF (5974.62 h-1)以及良好的长期稳定性(12 h)。对比实验表明，共存的 Ga 和 In 离子的协同效应和增强的界面电荷转移是促进CO2电还原活性的原因。此项目不仅有助于从分子团簇微观尺度上探明锡基材料的催化活性位点和催化机理，为设计高效二氧化碳还原电催化剂奠定基础，同时有助于拓展一类新型簇基二维纳米材料在光电器件、光/电催化等领域的应用。