Vink-van Ittersum Maaike E T, Betz-Güttner Erik, Hellebrand Eric, Keijzer Claudia J, Peerlings Matt L J, Ngene Peter, de Jongh Petra E
Materials Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University Universiteitsweg 99 3584CG Utrecht The Netherlands
Department of Earth Sciences, Utrecht University The Netherlands.
React Chem Eng. 2025 Jun 25. doi: 10.1039/d5re00068h.
The electrochemical reduction of CO combined with efficient CO capture is a promising approach to close the carbon cycle. We studied the effect of pore size on the activity and selectivity of porous Ag electrodes using template-based electrodes as model catalysts. Using polymer spheres with sizes between 115 nm and 372 nm as templates, ordered porous Ag catalysts with different pore diameters were obtained. These well-defined model systems allowed us to understand the effect of pore size on CO and H production. At the most cathodic potential, around -1.05 V, up to 4 times more CO than H was formed. The intrinsic CO production depends on the pore size, as it increases when changing the pore diameters from ∼100 nm to ∼300 nm. At pore diameters above ∼300 nm, the pore size does not affect the intrinsic CO production anymore. For the first time, FIB-SEM was used to quantitatively analyse the porosity of the electrodes and correlate it with trends in intrinsic activity. The catalyst with a pore diameter of ∼200 nm had the highest tortuosity of 2.41, which led to an increased CO production. The catalysts with a pore diameter of ∼200 nm and smaller have pore networks that are twice as long as the pore network of catalysts with ∼400 nm pores. This leads to an additional potential drop, which lowers the effective driving force for the electrochemical reaction. Disentanglement of these different factors is important for rational design of porous CO reduction catalysts.
将CO的电化学还原与高效的CO捕获相结合是实现碳循环闭合的一种很有前景的方法。我们使用基于模板的电极作为模型催化剂，研究了孔径对多孔银电极活性和选择性的影响。以尺寸在115 nm至372 nm之间的聚合物球体为模板，获得了具有不同孔径的有序多孔银催化剂。这些定义明确的模型系统使我们能够了解孔径对CO和H生成的影响。在最负的电位，约-1.05 V时，生成的CO比H多4倍。本征CO生成量取决于孔径，当孔径从约100 nm变为约300 nm时，本征CO生成量增加。在孔径大于约300 nm时，孔径不再影响本征CO生成量。首次使用聚焦离子束扫描电子显微镜（FIB-SEM）对电极的孔隙率进行定量分析，并将其与本征活性趋势相关联。孔径约为200 nm的催化剂具有最高的曲折度2.41，这导致CO生成量增加。孔径约为200 nm及更小的催化剂的孔网络长度是孔径约为400 nm的催化剂孔网络长度的两倍。这导致了额外的电位降，从而降低了电化学反应的有效驱动力。区分这些不同因素对于合理设计多孔CO还原催化剂很重要。
