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search.filters.applied.f.access: openAccess × End date: 2024 × Start date: 2020 × DDC: 500 × search.filters.applied.f.series: Nature Communications 14 (2023), Nr. 1 × Subject: catalyst ×

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    Reversibly growing crosslinked polymers with programmable sizes and properties
    ([London] : Nature Publishing Group UK, 2023) Zhou, Xiaozhuang; Zheng, Yijun; Zhang, Haohui; Yang, Li; Cui, Yubo; Krishnan, Baiju P.; Dong, Shihua; Aizenberg, Michael; Xiong, Xinhong; Hu, Yuhang; Aizenberg, Joanna; Cui, Jiaxi
    Growth constitutes a powerful method to post-modulate materials’ structures and functions without compromising their mechanical performance for sustainable use, but the process is irreversible. To address this issue, we here report a growing-degrowing strategy that enables thermosetting materials to either absorb or release components for continuously changing their sizes, shapes, compositions, and a set of properties simultaneously. The strategy is based on the monomer-polymer equilibrium of networks in which supplying or removing small polymerizable components would drive the networks toward expansion or contraction. Using acid-catalyzed equilibration of siloxane as an example, we demonstrate that the size and mechanical properties of the resulting silicone materials can be significantly or finely tuned in both directions of growth and decomposition. The equilibration can be turned off to yield stable products or reactivated again. During the degrowing-growing circle, material structures are selectively varied either uniformly or heterogeneously, by the availability of fillers. Our strategy endows the materials with many appealing capabilities including environment adaptivity, self-healing, and switchability of surface morphologies, shapes, and optical properties. Since monomer-polymer equilibration exists in many polymers, we envision the expansion of the presented strategy to various systems for many applications.
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    Steering carbon dioxide reduction toward C–C coupling using copper electrodes modified with porous molecular films
    ([London] : Nature Publishing Group UK, 2023) Zhao, Siqi; Christensen, Oliver; Sun, Zhaozong; Liang, Hongqing; Bagger, Alexander; Torbensen, Kristian; Nazari, Pegah; Lauritsen, Jeppe Vang; Pedersen, Steen Uttrup; Rossmeisl, Jan; Daasbjerg, Kim
    Copper offers unique capability as catalyst for multicarbon compounds production in the electrochemical carbon dioxide reduction reaction. In lieu of conventional catalysis alloying with other elements, copper can be modified with organic molecules to regulate product distribution. Here, we systematically study to which extent the carbon dioxide reduction is affected by film thickness and porosity. On a polycrystalline copper electrode, immobilization of porous bipyridine-based films of varying thicknesses is shown to result in almost an order of magnitude enhancement of the intrinsic current density pertaining to ethylene formation while multicarbon products selectivity increases from 9.7 to 61.9%. In contrast, the total current density remains mostly unaffected by the modification once it is normalized with respect to the electrochemical active surface area. Supported by a microkinetic model, we propose that porous and thick films increase both local carbon monoxide partial pressure and the carbon monoxide surface coverage by retaining in situ generated carbon monoxide. This reroutes the reaction pathway toward multicarbon products by enhancing carbon–carbon coupling. Our study highlights the significance of customizing the molecular film structure to improve the selectivity of copper catalysts for carbon dioxide reduction reaction.