基于多金属氧酸盐催化剂的光驱动产氢研究进展

能源和环境问题是21世纪人类面临的两个巨大挑战.鉴于此,为了实现人类社会的可持续发展,寻求能够替代化石能源的安全无污染可再生能源已迫在眉睫.太阳光驱动水分解是实现太阳能转化生产清洁可再生氢能的理想方法,其分解产物氢气和氧气在燃烧释放能量的同时生成洁净无污染的可饮用水,实现了完美的可持续能量循环,对于解决当今全球面临的能源危机与环境污染问题具有巨大的应用价值.然而,长期以来光驱动水分解所面临的巨大难题是半反应动力学非常缓慢,通常需要克服较高的能量势垒,导致整体能量转化效率低.利用非贵金属制备高催化效能、低成本的水分解催化材料成为该领域的研究热点和难点.目前,已报道的光驱动产氢催化剂可以被归纳为两大类:均相催化剂和异相催化剂.均相催化剂通常具备高催化活性、高选择性以及易于进行机理研究等优点,而异相催化剂则具备廉价、易得和高稳定性等优点;然而它们也存在一些不容忽视的问题,如均相催化剂的低稳定性、易分解失活,异相催化剂表面易被毒化失活、低催化转化数及转化频率等.如何设计合成兼具二者优点的产氢催化剂吸引了领域内研究者的广泛关注.作为一类新兴的多电子转移催化剂,多金属氧酸盐因其丰富多样的合成策略以及高度可调的物理化学及光化学性质,已被广泛用于催化水分解制氢气研究.该类多金属氧酸盐催化剂具备了介于均相分子化合物和异相金属氧化物之间的结构,这种独特的结构赋予它们同时具备均相分子催化剂的高活性、高选择性、高可控性、易于进行机理性研究等优点,又具备异相金属氧化物催化剂的廉价易得及稳定性高等优势.随着研究的开展,基于多金属氧酸盐的光催化产氢体系已由当初的贵金属辅助逐渐转变为丰产元素参与,光源的选择方面也从与太阳光谱匹配度低的紫外光转变为可见光.本文对30多年来基于多金属氧酸盐催化剂的光驱动产氢成果进行了综述,主要包括有/无贵金属辅助的多金属氧酸盐,多酸@金属有机框架复合物,多酸-半导体复合材料在紫外光或可见光条件下的光催化产氢研究;同时讨论总结了不同类型催化体系的反应机理;并对该领域的未来发展趋势及研究方向进行了展望.

Research advances of light-driven hydrogen evolution using polyoxometalate-based catalysts

With the increasing concerns to energy shortage and environmental problems in modern society, the development of cheap, clean, and sustainable energy alternatives has been attracting tremen-dous attention globally. Among various strategies of renewable energy exploration, solar-driven water splitting into its compositional elements H2 and O2 is an ideal approach to convert and store renewable solar energy into chemical bonds. In recent few decades, as an emerging new type of catalysts, polyoxometalates (POMs) have been widely utilized for water splitting due to their versa-tile synthetic methodology and highly tunable physicochemical and photochemical properties. This critical review addresses the research advances of light-driven hydrogen evolution using polyoxo-metalate-based catalysts, including plenary POMs, transition-metal-substituted POMs, POM@MOF composites, and POM-semiconductor hybrids, under UV, near UV and visible light irradiation. In addition, the catalytic mechanism for each reaction system has been thoroughly discussed and summarized. Finally, a comprehensive outlook of this research area is also prospected.