Layered double hydroxide (LDH)-based materials: A mini-review on strategies to improve the performance for photocatalytic water splitting

The high energy demand we currently face in society and the subsequent large consumption of fossil fuels cause its depletion and increase the pollution levels. The quest for the production of clean energy from renewable and sustainable sources remains open. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photoresponsive semiconductor catalysts, is one of the most promising technologies. Significant progress has been made on water splitting in the past few years and a variety of photocatalysts active not only under ultra-violet (UV) light but especially with the visible part of the electromagnetic spectrum have been developed. Layered double hydroxides (LDH)-based materials have emerged as a promising class of nanomaterials for solar energy applications owing to their unique layered structure, compositional flexibility, tunable bandgaps, ease of synthesis and low manufacturing costs. This review covers the most recent research dedicated to LDH materials for photocatalytic water-splitting applications and encompasses a range of synthetic strategies and post-modifications used to enhance their performance. Moreover, we provide a thorough discussion of the experimental conditions crucial to obtaining improved photoactivity and highlight the impact of some specific parameters, namely, catalysts loading, cocatalysts, sacrificial agents, and irradiation sources. This review provides the necessary tools to select the election technique for adequately enhancing the photoactivity of LDH and modified LDH-based materials and concludes with a critical summary that outlines further research directions.