Self-assembling hydrogel scaffolds for photocatalytic hydrogen production.
Self-assembling hydrogel scaffolds for photocatalytic hydrogen production.
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在超分子化学中，将产生可储存燃料所需的所有分子组分整合到软材料中是一个有趣的目标。这个概念的灵感来自于光合细胞器的内部结构，如植物叶绿体，它们共同定位参与光吸收，电荷传输和催化的分子，以产生与光能的化学键。我们在这里报告的光驱动生产氢内的水凝胶支架由超分子自组装的？单酰亚胺两亲物。形成的带电带可以静电吸引镍基催化剂，电解质屏蔽促进凝胶化。我们发现，通过催化剂或电解质的屏蔽，导致生色团组装体的二维结晶和增强分子之间的电子耦合的涌现现象。在水凝胶支架的三维环境中观察到氢的光催化产生，并且该材料容易放置在固体支持物的表面上或孔中。开发整合所有必要分子成分的软材料，以在阳光下产生可储存燃料，是一个尚未探索的化学领域，对可再生能源具有潜在影响。这样的系统可能具有优于使用大量液体、昂贵或有毒无机颗粒的分散体或复杂装置的优点。这种具有综合功能和高含水量的柔软材料的使用受到植物叶绿体内部结构的生物启发。这些光合细胞器已经进化为在其基质中的堆叠脂质双层内共定位蛋白质机器，其整合光吸收、电荷传输和将光能转化为化学键所需的催化功能。在过去的几十年里，模仿自然光合系统的努力集中在水氧化和质子还原的有效催化剂的开发上。在其他最近的工作中，催化剂已被耦合到光吸收的CdSe量子点，硅微棒，和有机染料，创造人工光合系统。还展示了能够使用地球丰富的资源进行水分解和燃料生成反应的功能装置。生物螺旋软材料的开发，可以塑造成形状，并整合光收集，电荷传输和催化功能，以生产太阳能燃料，这是一个明显的差距。这种差距可以通过自组装材料的策略来解决，其中自下而上的方法微调催化系统的所有功能方面。有机系统的寿命可能比无机系统短，但由于其软物质性质和生产所需的低能源，在可持续能源方面可能有自己的一席之地。我们在这里报告了一种策略，以创建超分子水凝胶，将光吸收发色团和催化剂整合到光驱动的氢气（H2）生产的材料中。我们在这里的工作只集中在创造一个可成形的催化材料所必需的超分子化学，因此没有探索它可能整合到一个光电阴极，不需要牺牲电子供体。我们设计了一种带电荷的两亲性生色团，它具有通过疏水性坍塌自组装成超分子聚合物的能力。在足够高的浓度和静电屏蔽条件下，带电的超分子聚合物可以很容易地产生凝胶形式的三维网络。这些网络可能是高度水合的，并含有生产太阳能燃料所需的可溶性成分。与此同时，与天然的光合作用天线一样，通过π轨道重叠形成的共轭分子的超分子结构应该具有吸收光、分裂激子并将电荷传输到催化反应中心的能力。尽管对共轭分子的凝胶化和光捕获能力进行了大量的工作，但尚未报道π-共轭凝胶用于人工光合应用的用途。通过分子设计，我们在这里展示了一个超分子催化体系，利用静电吸引将催化剂定位在发色团凝胶内。
Integration in a soft material of all molecular components necessary to generate storable fuels is an interesting target in supramolecular chemistry. The concept is inspired by the internal structure of photosynthetic organelles such as plant chloroplasts which co-localize molecules involved in light absorption, charge transport, and catalysis to create chemical bonds with light energy. We report here on the light-driven production of hydrogen inside a hydrogel scaffold built by the supramolecular self-assembly of a perylene monoimide amphiphile. The charged ribbons formed can electrostatically attract a nickel-based catalyst, and electrolyte screening promotes gelation. We found the emergent phenomenon that screening by the catalyst or the electrolytes led to two-dimensional crystallization of the chromophore assemblies and enhanced the electronic coupling among the molecules. Photocatalytic production of hydrogen is observed in the three-dimensional environment of the hydrogel scaffold and the material is easily placed on surfaces or in the pores of solid supports. The development of soft materials that integrate all necessary molecular components to generate storable fuels in the presence of sunlight is an unexplored area of chemistry with potential impact in renewable energy. Such systems could have advantages over the use of large volumes of liquids, dispersions of expensive or toxic inorganic particles, or complex devices. The use of such soft materials with integrated functions and high water content is bioinspired by the internal structure of chloroplasts in plants. These photosynthetic organelles have evolved to co-localize within stacked lipid bilayers in their stroma the protein machinery which integrates light-absorption, charge transport, and the catalytic functions necessary to convert light energy into chemical bonds. Efforts to emulate natural photosynthetic systems over the past several decades have concentrated on the development of efficient catalysts for water oxidation and proton reduction. In other recent work, catalysts have been coupled to light absorbing CdSe quantum dots, Si microrods, and organic dyes to create artificial photosynthetic systems. Also functional devices capable of performing water-splitting and fuel-generating reactions using earth-abundant resources have been demonstrated. The development of bionspired soft materials that can be shaped into forms and integrate light-harvesting, charge transport, and catalytic functions to produce solar fuels is an obvious gap. This gap can be addressed through self-assembly strategies for materials in which a bottom-up approach fine tunes all functional aspects of a catalytic system. Organic systems may have shorter lifetimes than their inorganic counterparts, but could have their own niche in sustainable energy given their soft matter nature and low energy requirements for production. We report here on a strategy to create supramolecular hydrogels that integrate both light-absorbing chromophores and catalysts into a material for light-driven hydrogen (H2) production. Our work here is focused only on the supramolecular chemistry necessary to create a formable catalytic material and therefore does not explore its possible integration into a photocathode that would not require a sacrificial electron donor. We designed a charged amphiphilic chromophore with the capacity to self-assemble into supramolecular polymers via hydrophobic collapse. At sufficiently high concentrations and under electrostatic screening conditions, charged supramolecular polymers can easily produce a three-dimensional network that takes the form of a gel. These networks could be highly hydrated and host the soluble components necessary to produce the solar fuel. At the same time, much like natural photosynthetic antennae, supramolecular structures of conjugated molecules formed through π orbital overlap should have the capacity to absorb light, split excitons, and transport the charges to catalytic reaction centers. Despite the large body of work on the gelation and light harvesting abilities of conjugated molecules, the use of π-conjugated gels for artificial photosynthetic applications has not been reported. Through molecular design, we demonstrate here a supramolecular catalytic system that localizes catalysts within chromophore gels using electrostatic attraction.
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DOI：
10.1126/science.1182340
发表时间：
2010-01-29
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Cui H;Pashuck ET;Velichko YS;Weigand SJ;Cheetham AG;Newcomb CJ;Stupp SI
通讯作者：
Stupp SI
影响因子：
4.6
作者：
Jain, Avijita;Lense, Sheri;Shaw, Wendy J.
通讯作者：
Shaw, Wendy J.
影响因子：
32.5
作者：
Poddutoori, Premaladha;Co, Dick T.;Wasielewski, Michael R.
通讯作者：
Wasielewski, Michael R.
影响因子：
32.5
作者：
Veldkamp, Brad S.;Han, Won-Sik;Wasielewski, Michael R.
通讯作者：
Wasielewski, Michael R.
影响因子：
15
作者：
Spano, Frank C.;Meskers, Stefan C. J.;Beljonne, David
通讯作者：
Beljonne, David