Search

Sunlight-driven water splitting allows renewable hydrogen to be produced from abundant and environmentally benign water. Large-scale societal implementation of this green fuel production technology within energy generation systems is essential for the establishment of sustainable future societies. Among various technologies, photocatalytic water splitting using particulate semiconductors has attracted increasing attention as a method to produce large amounts of green fuels at low cost. The key to making this technology practical is the development of photocatalysts capable of splitting water with high solar-to-fuel energy conversion efficiency. Furthermore, advances that enable the deployment of water-splitting photocatalysts over large areas are necessary, as is the ability to recover hydrogen safely and efficiently from the produced oxyhydrogen gas. This lead article describes the key discoveries and recent research trends in photosynthesis using particulate semiconductors and photocatalyst sheets for overall water splitting, via one-step excitation and two-step excitation (Z-scheme reactions), as well as for direct conversion of carbon dioxide into renewable fuels using water as an electron donor. We describe the latest advances in solar water-splitting and carbon dioxide reduction systems and pathways to improve their future performance, together with challenges and solutions in their practical application and scalability, including the fixation of particulate photocatalysts, hydrogen recovery, safety design of reactor systems, and approaches to separately generate hydrogen and oxygen from water.

Photocatalytic H2O2 generation system based on polymer catalyst receives increasing attention in recent years; however, the insufficient charge separation efficiency and low oxygen adsorption/activation capacity severely limit their potential application. In this study, a sulfur (C=S) functionalized polymer catalyst is reported through a green water‐mediated and catalyst‐free multi‐component reactions (MCRs) route. The sulfur functional group endows the polymer with a suitable energy band and facilitates the separation of photogenerated electron‐hole pair. The reported polymer achieves a high H2O2 production efficiency (3132 μmol g−1 h−1) in pure water without oxygen aeration. To demonstrate their potential in in situ wastewater treatment, a panel reactor system (20×20 cm) is constructed for large‐scale production of H2O2, which realizes continuous degradation of emerging pollutants including antibiotics and bisphenol A under natural sunlight irradiation condition. The H2O2 utilization efficiency of the photo‐self‐Fenton system using in situ generated H2O2 is found 7.9 times higher than that of the traditional photo‐Fenton system. This study offers new insights in green synthesis and design of functional polymer photocatalyst, and demonstrates the feasibility of panel reactor system for large‐scale continuous H2O2 photocatalytic production and water treatment. [ABSTRACT FROM AUTHOR]

Photocatalytic overall water splitting reaction driven by sunlight has been studied as a means of producing renewable solar hydrogen on a large scale. The practicality of this technology will ultimately depend on the cost of the produced solar hydrogen. This cost, in turn, is determined by various factors such as solar-to-hydrogen energy conversion efficiency, scalability, construction/operating costs and the service life of such systems. This article both summarizes the current state of development of photocatalytic overall water splitting technology and presents issues that must be addressed in the future to allow such systems to have real-world utility.