Supported metal oxide nanosystems for H2 photo-generation: quo vadis?

Hydrogen has attracted a great share of attention both as an energy carrier and as an irreplaceble reagent for many industrial processes. Photoactivated routes, ranging from photocatalytic and photo-electrochemical water splitting to photoreforming of suitable oxygenates, appear to be attractive long-term solutions among possible strategies for hydrogen production. However, the success of such processes depends on the efficient use of solar energy and on the identification of active and stable catalysts, which, in addition, should be eco-friendly and available in large amounts at accessible costs. Researchers are exploring the use of supported oxide nanomaterials, which enable an easy catalyst recovery and exhibit unique advantages due to their peculiar nano-organization. In this Feature Article, the potential of such systems towards photoinduced hydrogen evolution is discussed based on selected case studies that highlight the relations between structure, morphology, composition, and functional performances of oxide nanomaterials. In addition, potential limitations of oxide-based nanomaterials as well as unexplored key aspects that require special attention in future investigations are discussed