摘要:
近年来，自组装纳米结构因为其容易制备、稳定、环保以及与各种功能基团、粒子等的多样结合能力吸引了科学家们的目光，成为人们研究的热点课题，在光电池、光催化、水凝胶、药物缓释等方面的实验科学领域得到了广泛的应用。尤其是光催化方面，自组装结构的重复性为激子的传递创造了比较良好的条件，成为众多激子传递平台中的佼佼者。本文报道了一种以苯丙氨酸二肽纳米管和羧基石墨烯为基础的自组装光吸收催化平台，对其结构进行研究，并使用该体系进行了烟酰胺腺嘌呤二核苷酸到它的还原态的催化实验。该体系的微观结构由纳米管和石墨烯膜复合而成，羧基石墨烯的存在能够降低纳米管直径，实现纳米管的形态操控，石墨烯与多肽纳米管复合纳米结构的存在实现了多通道协同激子传递，降低了激子传递的距离，极大增强了催化中心对于激子的接受和使用效率。在复合了光敏剂和催化中心之后，该体系具有较高的稳定性，均一的分散性，很强的光能吸收和转化能力等性质。对于从NADP+往NADPH转变的催化实验表明，该体系有较高的反应速率和催化效率，并且比两种单一结构催化平台效果之和更好，实现了一加一大于二的效应，展现了复合纳米结构光吸收催化平台的巨大潜力和广阔应用前景。
Abstract:
Self-assembly is the way that is used by Mother Nature to create complex materials of hierarchical shapes and diverse functionalities. The photosynthesis apparatus of plant is an example of such complex materials that can direct convert the sunlight energy into chemical energy. Inspired by this, many artificial photosynthesis systems have been successfully engineered. However, most of these systems were based on only one type of simple nanostructure, such as nanosphere or nanotube. The charge separation and exciton transfer in such systems may be further improved by combining multiple nano-structures. Here, we report a novel photo catalysis system based on composite nanostructures of controllable peptide nanotubes and graphene. We use the mixture of diphenylalanine (FF) and carboxyl graphene for the photo catalysis because they are stable under different solvent conditions and highly conductive, which can provide more paths for exciton transfer. Moreover, the diameters of the peptide nanotubes become thinner in the presence of carboxyl graphene, leading to a more uniformly distributed system than simply using the peptide nanotubes alone. The FF peptide nanotubes can connect with the carbonyl graphene (CG) to form the composite nanostructures because of the π-π stacking interaction between benzene rings of FF and conjugated π bond of CG. The composite nanostructures of controllable peptide nanotubes and graphene provide more transmission channels for the excitions since they can travel on the nanotubes, CG or the compound of the both. We also demonstrate that when the photo-harvesting ruthenium complex and catalytic platinum nanoparticles are deposited on the system, the nicotinamide adenine dinucleotide (NADP+) can reduce to NADPH. The catalytic e?ciency and rate are much higher than thaose of other artificial photosynthesis systems reported in the literature. Surprisingly, we find that the catalytic e?ciency of the combined system is better than the sum of separated systems with only FF nanotubes or carboxyl graphene. The high turnover frequency, high reaction rate, and low toxicity of this artificial photosynthesis system will make the combined system attractive for large-scale applications, including optoelectronic industry, energy industry, etc.
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