基于场致效应的针尖结构d层电子饱和金属硫族电催化材料及CO2还原性能

Carbon dioxide (CO2) is the greenhouse gas that making global warming a pressing issue, and combining its electrochemical reduction with renewable energy sources is thus a promising way for recycling carbon emissions. The cost-effective d-orbit-filled metal chalcogenides have the capacity for reducing CO2 molecules into carbon-based fuels in aqueous solution as electrolyte, but their activity is still low. This is because the adsorption energy for CO2 molecules on d-orbit-filled metal elements is poor, resulting the low concentration of CO2 as the reagent on the surface of the electrocatalytic materials, which leads to the slow dynamic process for CO2 reduction reaction. Thus, this project will design and fabricate needle-tip structural electrocatalysts, because this structure can induce field that concentrates electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. In addition, the atomic step structure on needle-tip could enhance the catalytic performance of materials. Therefore, these could improve the CO2 reduction activity of d-orbit-filled metal chalcogenides as electrocatalysts. Herein, some novel needle-tip-structured d-orbit-filled metal chalcogenide catalysts will be controllably synthesized by means of theoretical and experimental studies, and the relationship of the formation-evolution mechanism of different needle-tip structures and reaction environment will be revealed. Moreover, the design and modulation methods for needle-tip-structured materials synthesis will be established. Furthermore, by using the theoretical simulation and advanced characterizations, the influence of the field-induced effects caused by different needle-tip structures on the transfer and conversion performance of CO2 will be investigated, and the relationship between the field-induced effects and the reaction activity will be concluded. Through the implementation of this project, a series of high-activity and high-selectivity d-orbit-filled metal chalcogenide materials for electrocatalytic CO2 reduction via field-induced effects in aqueous solution will be developed.

电催化还原CO2是实现环境高效碳循环的理想途径。其中，廉价的d层电子饱和过渡金属硫族化合物可在水相体系中高选择性地电催化还原CO2，但该类材料对CO2吸附能较弱，其表面过低的反应物浓度导致动力学过程较慢，使得反应活性较低。因此，本项目将针尖结构诱导的“场致效应”引入该类材料中，通过增加材料表面反应物CO2浓度来加速动力学过程，且针尖表面的原子台阶等结构有助于增强材料催化性能，从而提升反应活性。拟采用理论与实验相结合的方法，揭示材料针尖结构形成演化机制与反应环境间的内在关联，建立不同针尖结构的设计与调控机制；借助模拟与先进表征手段，阐明不同针尖结构对场致效应的影响及场致效应对CO2传递与转化过程的作用规律；最终开发出多种基于场致效应的针尖结构d层电子饱和金属硫族电催化材料，实现其在水相体系中高活性和高选择性地还原CO2。

利用电催化方法将CO2转化为化学品或燃料被认为是实现能源转换、化学储能、以及“碳中和”的有效途径之一。在CO2还原中，电催化剂的本征性质直接决定着催化过程的反应活性和选择性。d层电子饱和金属硫族化合物具有较弱的氢吸附能，可优化反应物传递过程。本项目合成了多种d层电子饱和金属硫族化合物以及其他化合物，包括Bi2S3、硫杂化层状化合物和BiPO4等催化剂材料，并考察了电催化性能，研究了相应的催化机理。.1、通过水热法制备了棒状Bi2S3，经过原位电化学还原得到衍生电催化剂，当施加电位为-1.0 V时，其制甲酸盐法拉第效率为82％，电还原CO2测试稳定性超20小时。.2、设计制备了低配位硫杂化的NiCo层状双氢氧化物并用于甲醇氧化成甲酸盐，起始电位仅需1.22 V，且在100 mA cm-2时工作电位仅为1.39V。与阴极CO2还原配对后，在300 mA cm-2的高电流密度下，实现了2.48 V的低全电池电压下的选择性配对甲酸盐电合成，阴阳两极制甲酸盐的法拉第效率均达100%。.3、通过水热法制备由颗粒组成的BiPO4，通过原位电化学还原得到衍生电催化剂，在-0.9 V工作电位时，甲酸盐法拉第效率达到最高，为91.4%。在200 mA cm-2的高电流密度下，其制甲酸盐法拉第效率超90%，阴极能效达73%。 .这些工作在Angewandte Chemie International Edition等期刊发表标注论文12篇，申请中国发明专利4项，均已公开。项目负责人在项目资助期间获得国家留学基金委公派博士后项目、国家自然科学基金委面上项目，并入聘华东理工大学副教授。