有序介孔壳层/纳米线多级结构的可控合成及其光解水催化与电化学储能

This project aims at the high efficiency of solar energy conversion and storage, and focuses on the two important challenges: the design of semiconductor photoelectrode materials/structures, and the storage of photocatalysis energy. In this project, we propose to rationally synthesize one-dimensional semiconductor photoanode and photocathode arrays with Z-scheme energy structures. In addition, by using a surfactant-templated organic-inorganic self-assembly process, mesoporous shell layers with ordered pore structure and perpendicular pore orientation are grown on the nanowire photoelectrode surface, and served as structured units for hydrogen evolution catalyst and electrochemistry energy storage. These ordered mesoporous-shelled, nanowire hybrid structures have suitable energy band alignment, large specific surface area, long light absorption distance, short charge separation, tunable mesopore size, one-dimensional charge transport properties, and thus are beneficial for improving solar energy absorption, electron/hole pair separation, interface charge transfer, charge transport inside materials, and electrochemical reaction kinetics. Therefore, much enhanced efficiencies in photo-electric conversion, hydrogen evolution and electrochemical energy storage are expected. By the "structure design - material synthesis - property measurement - feedback and optimization" strategy, we further expect to explore new concept for photoelectrode design, and illustrate the relationships between material structures with photocatalytic hydrogen formation and electrochemical energy storage. Moreover, this project will offer new scientific support for novel electrode composites that allow for spontaneous, simultaneous solar-driven water splitting and electrochemical energy storage.

本项目以太阳能的高效转化和存储为目标，针对半导体光电极的结构设计，与光催化反应能量的存储这两个重要的瓶颈问题，拟可控合成具有Z型能级结构、一维纳米线阵列的半导体光阳极与光阴级，并进一步利用表面活性剂分子诱导的自组装，在纳米线表面生长具有有序介孔结构、且孔道取向垂直于基底的介孔壳层，分别作为产氢催化剂与电化学储能结构单元。该有序介孔壳层/纳米线结构具有合适的能级分布、高比表面、长的光吸收程、短的电荷分离程、可控的介孔尺度、一维连续的电荷传输等结构优点，有利于提高太阳光能吸收、电子与空穴的分离效率、界面电荷转移、材料内电荷传输与电化学反应，以获得具有高光电转化效率、产氢效率与电化学储能容量的介孔/纳米线复合材料。通过"结构设计-材料合成-性能测试-反馈优化"，拓展光电极设计理念，阐明材料结构与光解水产氢、电化学储能的规律，为开发新型、可自发、同时进行光催化和电能存储的复合电极材料提供科学依据。

本项目面向太阳能的高效转化和电能的高效存储的需求，设计合成具有同时光电催化分解水、CO2还原的光阳极、光阴级材料与电催化剂，以实现自发、高效的光电转化、以及化学能的存储与高效利用。通过本项目的研究，我们获得如下主要结果。（1）在合成复合介孔/纳米材料的新结构方面，提出界面上或限域空间内，合成具有多级、多尺度、能级匹配的复合介孔/纳米线材料的新机理与新方法；（2）通过研究材料生长中的热力学与动力学规律，研究多组分材料结构、能级匹配规律，提出构效关系与能级调控的新策略，提高其光吸收与光电转化活性；（3）提出了多种过渡金属氧化物的晶格结构、缺陷、价态调控、掺杂的调控方法，成功地制备了多种高性能的电解水产氧催化剂，显著降低了水氧化反应的过电势，提高电流密度和转化效率，并探索其作为双功能催化剂进行电分解水等方面的应用；（4）利用界面电化学催化反应，发展了新型的电能存储材料与分子检测方法。通过催化剂的合成调控，实现界面电荷的高效转移，并将电化学能储存在电极中，获得高功率密度的水系锂离子电池。此外，通过在电极表面连接上具有选择性识别溶液中待测物的分子层，发展了多种高灵敏度的分子传感检测方法。通过本项目的研究，有望发展基于纳米材料的新型的清洁能源转化和储存的技术，发展可作为高效太阳光分解水的半导体电极材料与催化剂。