均相光催化制氢体系有机染料光敏剂的研究进展

Research Progress of Organic Photosensitizers for Homogeneous Photocatalytic Hydrogen Production System

氢能是一种理想的清洁型新能源,在可再生能源中占据重要地位。现阶段国内氢能的发展仍然面临技术不成熟导致的生产效率较低、制氢体系不稳定及氢能应用的综合成本过高等问题,从而阻碍了氢能产业链的发展。我国在碱性电解水制氢与煤气化制氢方面的技术优势明显,制氢规模位居世界首位,但在可再生能源制氢如光催化制氢、电催化制氢等方面,与国际顶尖技术相比还存在较大差距。光催化制氢技术分为非均相制氢和均相制氢两种。由于非均相制氢体系多以半导体为光催化剂,其光吸收效率低且产氢效率并不理想。对于由光敏剂、催化剂和牺牲电子供体组成的均相体系而言,其结构组成简单,便于灵活的系统设计,是颇具潜力的制氢技术。其中光敏剂作为制氢反应的能量捕获器,其选取尤为关键。目前研究最多的是贵金属及其配合物类光敏剂,然而贵金属资源少、成本高,限制了进一步发展。采用纯有机染料代替贵金属基光敏剂构建非贵金属光催化制氢体系有望为均相光催化制氢体系的发展带来新突破。非贵金属光催化制氢体系中的纯有机光敏剂主要分为含氮杂环类、氧杂蒽醌类、氟硼吡咯类和香豆素类等。目前对纯有机染料光催化制氢性能的研究表明其制氢效率要远高于相同实验条件下的金属基光敏剂。由于有机染料存在良好的构效特性,通过结构的设计和修饰可以达到改变和优化光敏剂性能的目的。并且纯有机染料不含金属类元素,具有低廉的成本、丰富的资源,便于合成,逐渐成为该领域研究人员的新宠。本文从均相光催化制氢体系出发,简要介绍了包括体系基本组成、结构类型、光化学理论基础以及制氢机理分析与性能的研究,重点而详细地综述了有机染料为光敏剂的非贵金属光催化制氢体系的研究进展,并对应用有机染料作为制氢体系光敏剂突出特性的筛选设计做出展望,进一步明确未来氢能源技术的发展方向。

Hydrogen energy is kind of an ideal clean new energy and plays an important role in renewable energy.At this stage,the development of hydrogen energy in China still faces many challenges,such as the low production efficiency due to the immature technologies,the instability of hydrogen production system,and the high cost of hydrogen energy applications,which hinders the development of hydrogen energy industry.China has obtained leading technological advantages in hydrogen productions from alkaline electrolytic water and coal gasification.Although China ranks first in the scale of hydrogen productions,there is still a big gap between China and the international top technologies in renewable energy hydrogen production,such as photocatalytic and electrocatalytic hydrogen production.Generally,photocatalytic hydrogen production technology can be divided into two types,heterogeneous and homogeneous hydrogen production technologies.Since most heterogeneous hydrogen production systems use semiconductors as photocatalysts,their light absorption efficiency is low and hydrogen production efficiency is not high.For a homogeneous system composed of photosensitizers,catalysts and sacrificial electron donors,it is a potential hydrogen production technology because of its flexible structure easy to design and adjust systematically.Among them,the photosensitizer is used as the energy harvester for the hydrogen production reaction,and its selection is particularly critical.Recently,noble metals and their complexes photosensitizers have been widely studied.Owing to its limited resource and high cost,the research and development of noble metals based photosensitizers are restricted.As an alternative,the use of pure organic dyes to construct non-noble metal photocatalytic hydrogen production systems is expected to bring a new breakthrough in the development of homogeneous photocatalytic hydrogen production system.In the non-noble metal photocatalytic hydrogen production system,the pure organic photosensitizers are mainly divided into nitrogenous heterocycles,xanthenes,bodipys and coumarins.The current research on the photocatalytic performance of pure organic dyes for hydrogen production shows that their hydrogen production efficiency is much higher than that of metal-based photosensitizers.Because organic dyes have good structure-activity characteristics,the performance of photosensitizers can be changed and optimized by structural design and modification.In addition,pure organic dyes do not contain metal elements,are cost-effective,rich in resources,and easy to synthesize,and thus have gradually arose much attention in hydrogen production.In this review,we firstly discussed the homogeneous photocatalytic hydrogen production system,including its basic composition,structure types,photochemical theoretical basis,hydrogen production mechanism analysis and performance research.The advances of non-noble metal photocatalytic hydrogen production system with organic dyes as photosensitizer is reviewed with particular emphasis.Finally,current trends related to the screening design of using organic dyes as photosensitizers for hydrogen production system is outlined,and we further clarified the development direction of hydrogen energy technology.