超薄金属氧化物的调控合成及其离子液体中电催化还原CO2性能研究

Due to its unique physicochemistry properties, the ultrathin metal oxides with two-dimensional (2D) structure (UMOs) have broad potential applications in the electrocatalytic reduction of CO2. In this project, a novel wet-chemical method based on hydrogen-bonding of structure directing agent will be developed to synthesize the UMOs with a thickness less than 2 nm, aiming at preparing a series of UMOs including TiO2 and CeO2 etc. The influences of experimental factors, such as structure directing agent, on the structures of metal oxide will be systematically investigated. Furthermore, a series of metal (M, such as Cu, Ni, Sn and Au)-supported UMOs will be prepared. Using the ionic liquids that can absorb CO2 with high capacity as the catholyte, the as-synthesized UMOs or M/UMOs as electrocatalysts, the electroreduction of CO2 into value-added chemicals (methanol, ethylene and ethanol etc.) will be investigated, and the influences of the catalysts, catholyte, the interaction between UMOs and the ionic liquid electrolyte on the overpotential of CO2 reduction, current efficiency, selectivity to target products and durability of the electrocatalysts will be systematically studied. This project is not only intended to develop a method to prepare UMOs, but also expected to achieve efficient electrocatalytic system for CO2 reduction, and make a great progress on understanding the electrochemical conversion of CO2. This project is related to the multidisciplinary overlap of physical chemistry, material science and green chemistry, which is of significance from the viewpoint of theoretical research and applications.

二维超薄金属氧化物（UMOs）具有特殊的物化性质，在电催化还原CO2方面具有潜在的应用前景。本项目拟发展氢键诱导的可控制备UMOs（厚度<2 nm）的新方法，并合成一系列UMOs（如TiO2和CeO2等），系统研究结构诱导剂等条件对材料形貌的影响规律，揭示形成机理，并制备负载型金属M/UMOs。以CO2吸收容量高的功能离子液水溶液为电解液，（M/）UMOs为电催化剂，进行CO2电还原生成甲醇、乙烯和乙醇等高附加值化合物的研究，考察UMOs结构、电解液组成、UMOs与离子液匹配等对CO2还原的过电位、电流效率、产物选择性和电极稳定性的影响规律，揭示材料构效关系、离子液与UMOs的匹配耦合机制以及CO2电还原反应机理。本项目旨在发展制备UMOs方法的同时，获得CO2电转化的高效催化体系，有望在CO2清洁高效转化方面取得重要进展。项目研究涉及物理化学、材料科学和绿色化学的交叉渗透，具有重要意义。

电催化还原CO2制备能源产品和化学品对可持续发展具有重要意义，是当今科学研究的前沿领域。本项目制备了多种金属氧化物/硫化物纳米复合材料，构建了离子液体电解液-金属氧化物电催化材料耦合反应体系，进行了CO2 电催化还原反应研究，考察了各因素对反应的影响，揭示了催化反应机制，取得一些重要研究成果。例如，制备了碳包覆的Cu2O纳米颗粒，以浓度为30%的 [Bmim][BF4]-乙腈溶液作为电解液，可将CO2电催化还原为乙烯，其法拉第效率达49%，电流密度达47 mA/cm2；制备了导电聚合物凝胶负载的CuO纳米颗粒，采用浓度为30%的 [Bmim][BF4]-乙腈溶液为电解液，可将CO2电催化还原为甲酸，其法拉第效率最高可达99%，电流密度最大可以达到113 mA/cm2；制备了SnS2纳米片，在 [Bmim][BF4]-乙腈电解液体系中，能够有效地将CO2还原为甲酸，CO2还原的法拉第效率高达82%，电流密度最高可达52 mA/cm2。研究发现，离子液体能够有效地降低CO2的反应活化能，并修饰电催化材料的电子结构，稳定反应中间体，离子液体与电催化材料的协同作用实现对CO2的电催化还原。本项目取得的研究成果丰富了电催化还原CO2的研究内容，对相关领域的发展具有一定的推动作用。