WO3/AuNR/卟啉组装体Z-型光催化剂的构筑及可见光全解水性能研究

Photocatalytic water splitting to hydrogen is one of the important ways to use solar energy to obtain clean energy. Wide spectral absorption and high-efficiency charge separation performance are key factors for the construction of high-efficiency photocatalysts, and the construction of high-efficiency Z-type photocatalysts is an effective method to solve this problem. This project proposed to fix porphyrin assembly (PA) with broad spectral absorption and WO3 based on energy level matching with PA to the two ends of the AuNR with excellent electron transport properties through a two-step method, then the dumbbell-shaped WO3/AuNR/PA composite Z-scheme photocatalyst was obtained. While broadening the spectral absorption range of the composite catalyst, space charge separation was achieved using AuNR as an electron transport medium. At the same time, electrons of WO3 combine with holes of PA to avoid the reduction of WO3 and the oxidation of porphyrin, which increased the stability of the catalyst. It is expected to obtain efficient visible light-driven water splitting performance. The functional mechanism of AuNR end organic ligand modification on the coordination assembly of pyridyl porphyrins was elucidated by researching the directional porphyrins assembly process. The electron-hole transport pathways of WO3 and PA in the catalytic process were investigated to reveal the effect mechanism of the dumbbell-shaped structures dependent electron-hole transport separation property. This project will provide a theoretical basis and experimental basis for the development of novel highly effective overall water splitting Z-scheme photocatalysts based on porphyrin assemblies.

光催化分解水制氢是利用太阳能获得清洁能源的重要途径之一。宽光谱吸收和高效电荷分离性能是构建高效光催化剂的关键因素，而构建高效Ｚ型光催化剂是解决该问题的有效方法。本项目拟构建两步法将具有宽光谱吸收的卟啉组装体（PA）和与之能级匹配的WO3固定在具有优异电子传输性能的金纳米棒（AuNR）两端，得到哑铃形WO3/AuNR/PA复合Z型光催化剂。在拓宽复合催化剂光谱吸收范围的同时，利用AuNR作为电子传输介质实现空间电荷分离，同时WO3的电子与PA的空穴相结合，避免了WO3的还原和卟啉的氧化提高了催化剂的稳定性，有望获得高效的可见光全解水性能。通过研究卟啉的定向组装过程，阐明AuNR端基配体修饰对吡啶基卟啉配位组装的作用机制；研究WO3和PA在催化过程中电子-空穴传输路径，揭示该哑铃形结构对电子空穴传输分离的影响机制，为发展基于卟啉组装体的新型高效Z型全解水光催化剂提供理论依据和实验基础。

可见光催化全解水制氢是获取清洁可再生能源氢能的理想方法，同时也是有效缓解目前人类面临的能源和环境问题的理想途径之一。高效Ｚ型光催化剂既有效抑制光生电子空穴的复合，又保留催化材料原有的氧化还原能力，具有重要的研究前景。本项目1）采用酸碱中和胶束限域组装的方法，以WO3纳米棒为基底，以ZnTPyP为组装基元，制备得到ZnTPyP组装体/WO3有机-无机Z型复合纳米材料，建立了卟啉Z型复合材料的设计思路和合成方法。调控乳化剂种类、组装溶液pH值以及WO3纳米棒的投入量，利用ZnTPyP上吡啶基N与WO3中W原子的配位作用，实现ZnTPyP在WO3纳米棒上的可控组装和卟啉与WO3组合方式的控制，揭示组合方式与光催化制氢性能的构效关系。光催化制氢结果表明，ZnTPyP/WO3肩并肩结构复合催化剂的速率高达74.53 mmol/g/h，是ZnTPyP自组装体的2.62倍；能带结构的表征和计算证实ZnTPyP/WO3复合材料为直接Z型光催化剂。2）将Au纳米颗粒作为电子媒介引入ZnTPyP/WO3复合界面，Au颗粒显著增强电子空穴对的分离，光催化产氢测试结果表明相比于ZnTPyP/WO3，ZnTPyP/Au/WO3制氢速率得到了进一步的提升，为ZnTPyP/WO3的1.54倍，是ZnTPyP组装体的4倍。3）通过调控酸的种类/浓度、CTAB的浓度和钨酸盐的水解速度，实现在Au纳米棒的一端包裹钨酸，制备得到一系列具有不同组成和孔结构的WO3/AuNR蘑菇状纳米复合材料。4）通过调控乳化剂的种类/浓度、Au棒的浓度、4-巯基吡啶的浓度，卟啉的浓度，实现在Au纳米棒的一端包裹卟啉自组装体，制备得到一系列具有不同组成的卟啉/AuNR核壳结构纳米复合材料，获得了较好的光热性能。5）资助期间共发表SCI论文5篇，包括MRS Bull.、APL Mater.、J. Phys. Chem. C等，申请专利8项，授权7项；获批中国博士后科学基金第1批特别资助（站前）项目，协助课题组长培养在读博士生2个，硕士生11个（已毕业5个），本科生4名（毕业1名）。参加国际/国内会议5次，会议报告1次，以第二完成人获河南省自然科学二等奖，河南省教育厅科技成果奖一等奖等奖项。