类单晶结构多孔碳基薄膜的可控制备及其电催化二氧化碳转化研究

Sustainable conversion of CO2 into value-added chemicals under ambient condition has a significant effect on economic development and society benefit. Searching for scalable and stable electrocatalysts for the CO2 reduction reaction (CO2RR) is the key challenge in electrocatalytic CO2 conversion system. Carbon-base electrocatalysts are particularly attractive in the fields of energy conversion and electrocatalysis due to their low cost, chemical stability as well as tunable conductivity. However, nowadays the widely-studied carbon-based electrocatalysts almost exclusively exist in powder form, when they are utilized as electrodes in practical electrocatalytic process, they suffered from complicated engineering procedures, low catalytic activity, deteriorated long-term operational stability as well as other drawbacks. To overcome these experimental hurdles and raise the technological potential of carbon-based electrocatalysts to drive efficient electrocatalytic CO2RR, in this project, the highly ionic cross-linked precursors are designed and applied to in-situ preparation of single-crystal-like hierarchical nanoporous carbon membranes, which can be directly utilized as electrode for electrocatalytic conversion of CO2. The p-n Junctions and Mott-Schottky effects are employed to tune the electrocatalytic performance of as-prepared carbon membranes. This project will thoroughly investigate and study the effect of structures and compositions of as-prepared carbon membranes as well as types of electrolytes on the electrocatalytic performance of CO2RR. Furthermore, we will probe into the process of absorption and migration of CO2 molecular on the surface of carbon membranes by combining experimental results, in-situ characterizations and molecular dynamic simulation, offering a novel strategy and theoretical evidence for rational designing high performance electrocatalysts for CO2 conversion.

常温常压下将CO2电催化转化为高附加值的化学品具有重大的经济价值和社会效益。电催化CO2转化的核心技术是研发高效稳定且易大规模生产的电催化剂。碳基催化剂因其价廉易得等优点在能源转化、电催化领域备受青睐。目前，碳基催化剂的研究仍处于调控粉末状碳材料的微结构和组分阶段。针对目前粉末碳基电极制备工艺复杂，催化活性低和稳定性差等缺陷，本项目旨在通过设计合成离子交联的前驱体，原位制备具有类单晶结构、多级孔结构并可直接作为电极使用的碳基薄膜，探索其在电催化CO2转化领域的应用。通过p-n异质结、莫特肖特基效应来调控碳基薄膜的催化性能。深入考察碳基薄膜的结构、组成及电解质种类等对CO2还原性能和还原产物的影响。结合原位表征技术和分子动力学模拟，深入探讨CO2分子在碳基薄膜催表面的吸附、迁移等重要过程，阐释碳基薄膜电催化CO2还原反应的作用机制，为理性设计高性能的CO2转化电催化剂提供新的思路和理论依据。

设计开发高性能多孔碳膜的宏量制备技术是一项具有重要意义和应用价值的研究方向。杂原子掺杂多孔碳膜的规模制备主要取决于软模版和炭化工艺的进展，其中软模板是需要优先解决的问题。首先合成了系列功能聚离子液体，通过静电络合诱导相分离的方法，宏量制备了系列孔径可调控的全聚离子液体多孔膜。深入探讨了聚离子液体结构与其孔径之间的构效关系。研究结果表明，聚阳离子的亲疏水性能对孔径的影响较小，但可大幅度改变膜的机械性能；阴离子的亲疏水性能对孔径的影响较大，越疏水，膜的孔径越小。我们成功开发了系列孔径从70 nm~5μm可大范围调控的全聚离子液体多孔膜；进一步地优化了炭化工艺。大量实验结果表明，相比较传统惰性气体保护的炭化过程，真空炭化可大幅度提高多孔碳膜的结晶度及电导率。此项研究建立了一种全聚离子液体多孔膜的可控制备方法，发现了真空炭化工艺是制备高性能碳材料的有效方法。通过聚离子液体结构设计结合真空炭化工艺，实现了多孔碳膜孔径的精准调控及多功能化，实验室规模制备了系列高性能多孔碳膜，所制备的杂原子掺杂的多孔碳膜直接作为电极在电化学能源转化领域具有了良好的应用价值，为高性能多孔碳膜的设计制备提供了新材料和技术。