纳米多孔Au-Cu、Au-Pd电催化选择性的动力学调控机理

Electrochemical catalysis involved by multiple electrons and protons plays an important role in energy storage and conversion, promoting the global carbon cycle. Amongst these reactions, oxygen reduction reaction and carbon dioxide reduction will induce a variety of intermediate species, so that catalytic selectivity of electrochemical electrodes is the key issue during the composition design and structure optimizations of the catalysts. This project intends to construct nanoporous Au-Cu, Au-Pd alloy catalysts, and tailor the absorption energies of key intermediates such as *OH, *OOH, *CO and *COOH at various atomic sites by adjusting bulk composition, coordination environment, surface composition, and pore size. Based on surface plasmon excitation of nanoporous metals to refractive index of surrounding dielectrics and the conventional monitoring of the output products, the temporal evolution of the intermediates and final products can be quantitatively measured. In this case, different experimental parameters such as the overpotential, electrolyte composition, partial pressures of the reducible gases in the electrolytes, and pH value can assist the improved selectivity of catalytic reactions, in which case the kinetic parameters k of catalytic reactions getting involved with the key intermediate product should be reliably evaluated and balanced. This project intends to reveal the catalytic kinetics of nanoporous alloys and establish a quantitative model to describe the rule to unravel the kinetics principle to improve catalytic selectivity. The targeting outcome of this project will benefit to reveal the mechanism of molecular adsorption, charge transfer and electrochemical catalysis at single atomic site, and provide theoretical support for the rational design of alloy catalysts with high performances.

多电子和多质子参与的电催化反应在能源存储与转换、促进全球碳循环等领域具有举足轻重的作用，其中氧还原和二氧化碳还原的中间产物种类繁多，催化选择性成为电极成分与结构设计的关键因素。本项目拟构建多孔Au-Cu、Au-Pd合金催化剂，通过调节块体成分、配位环境、表面组分、孔径等参数来精细调控*OH、*OOH、*CO和*COOH等关键中间产物在不同原子位点的吸附能。利用多孔合金的表面等离激元和折射率传感性能，结合气相和液相产物检测方法，测量中间产物和生成物的时域演化趋势。计算与中间产物关联的反应动力学参数k，并结合过电位调节、溶液成分、气体分压、pH值等实验条件来协调生成和消耗关键中间产物的k值，从而提高终端产物的选择性。本项目拟揭示多孔合金的催化动力学规律，建立定量模型来描述催化选择性的动力学调控原理。将有助于揭示单原子位点的分子吸附、电荷转移、电催化机理，为设计高性能合金催化剂提供理论基础。

近年来，以二氧化碳还原反应为代表的多电子、多质子电催化反应在能量转化、能源存储以及碳中和等研究领域受到越来越多的关注。调节反应的速率决定步骤，调节催化剂与各种中间产物之间的吸附能，从而提高目标产物的选择性与电流密度是二氧化碳催化还原领域的核心与难点。我们设计纳米多孔合金的成分与表面形貌，通过晶面调控与原子迁移优化催化电极的电子结构，取得以下成果：(1) 诱导纳米多孔合金的元素偏析，使催化电极发生表面重构，从而提高催化反应的产物选择性和电化学活性；(2) 通过晶面调控和引入拉伸应力，调节纳米多孔金的表面能，优化催化电极与中间产物之间的吸附作用，提高催化反应的活性；(3) 设计并制备多级多孔壳层和纳米薄片，分析反应物传输动力学与催化选择性的关联。此外，在制备纳米材料用于电化学催化析氢反应、可见光单向散射和紫外光区表面等离激元共振等研究也取得了成果。