With the increased demand for green and sustainable sources of fuels, photocatalytic hydrogen gas production using semiconductor catalysts is attracting tremendous attention. In this perspective article, we will discuss the state-of-the-art development of small molecule-based semiconductors for photocatalytic green hydrogen production. Organic small molecules have the benefits of easy structural engineering allowing fine modulation of optical and electronic properties for the development of efficient photocatalysts. Small molecule-based photocatalyst development is advantageous compared to that of their polymer counterparts due to various reasons including less tedious synthesis, easily tunable optical and electronic properties, improved water dispersibility, etc. Conjugated donor–acceptor, porphyrin, perylene, and organic heterojunction nanoparticles are discussed in this article for their photocatalytic activity in the hydrogen evolution reaction. We have highlighted literature reports emphasizing the impact of heteroatom substitution, conjugation, band gap, exciton diffusion length, planarity, crystallinity, molecular packing, water solubility, etc. on photocatalytic performance.

中文翻译：

---

小分子作为光催化剂向生产绿色氢的演变


随着对绿色和可持续燃料来源的需求增加，使用半导体催化剂的光催化氢气生产引起了极大的关注。在这篇前瞻性文章中，我们将讨论用于光催化绿色氢气生产的基于小分子的半导体的最新发展。有机小分子具有易于结构工程的优点，允许对光学和电子特性进行精细调制，以开发高效的光催化剂。由于各种原因，基于小分子的光催化剂开发优于聚合物，包括合成不那么繁琐、易于调整的光学和电子特性、改进的水分散性等。本文讨论了共轭供体-受体、卟啉、苝和有机异质结纳米颗粒在析氢反应中的光催化活性。我们重点介绍了杂原子取代、共轭、带隙、激子扩散长度、平面度、结晶度、分子堆积、水溶性等对光催化性能的影响的文献报告。