An Overview of the Photocatalytic H2 Evolution by Semiconductor-Based Materials for Nonspecialists

The solar-to-chemical energy conversion is promising to tackle sustainability challenges toward a global future. The production of H2 from sunlight represents an attractive alternative to the use of carboniferous fossil fuels to meet our energy demands. In this context, the water splitting reaction photocatalyzed by semiconductors that can be excited under visible or near-infrared light excitation represents an attractive route to the clean generation of H2. In this review, we present an overview of the most important concepts behind the H2 generation, from water splitting, promoted by semiconductor-based systems for readers that were recently introduced to the water splitting topic. Then, we present the main classes of photocatalysts based on semiconductors. For each class of semiconductors, we focused on the examples that lead to the highest activities towards the H2 production and discuss the operation principles, advantages, performances, limitations, and challenges. We cover metal oxides, sulfides, and nitrides. We also discuss strategies in which these materials are combined, including hybridization with metal nanoparticles, other semiconductors, and carbon dots, to achieve improved performances and circumvent the limitations of the individual counterparts.

太阳能-化学能转化技术有望应对全球可持续发展面临的诸多挑战。利用太阳光制备氢气(H2)，是替代含碳化石燃料以满足能源需求的极具吸引力的方案。在此背景下，可在可见光或近红外光激发下产生光响应的半导体光催化水分解反应，是实现清洁制氢(H2)的极具潜力的路径。
本综述面向刚接触水分解领域的读者，系统梳理了基于半导体体系催化水分解制氢(H2)背后的核心概念与关键原理。随后，本文介绍了半导体基光催化剂的主要类别。针对每一类半导体，本文重点选取了制氢(H2)活性最高的代表性案例，并对其工作原理、优势、催化性能、局限性及面临的挑战展开讨论。本文涵盖金属氧化物、硫化物及氮化物三类光催化剂体系。此外，本文还探讨了这类半导体材料的复合改性策略，包括与金属纳米颗粒、其他半导体及碳点(carbon dots)复合，以提升催化性能并规避单一材料的固有局限。