Layered double hydroxide for photocatalytic application toward CO2 reduction and water splitting: Recent advances, synthesis, heterojunction formation, challenges, and future directions

Solar fuel production through water splitting and CO2 reduction by employing photocatalytic materials is a paradigm track to present renewable energy sources and lessen global warming. Among these materials, layered double hydroxides (LDHs) have been widely investigated in CO2 reduction and water splitting to produce chemical fuels. However, pure LDHs suffer from sluggish charge-carrier transport, a great electron–hole recombination rate as well as tend to cause agglomeration. Due to the aforementioned bottlenecks, numerous modification techniques have been considerably explored to enhance the potential of LDHs toward photocatalytic water splitting and CO2 photoreduction. Therefore, this article presents a thorough review of developments made for the construction and modification of LDH photocatalyst properties aiming to enhance water splitting and photocatalytic CO2 reduction. The review starts with the techniques adopted to synthesize LDH-based structures toward enhanced structure and morphology. The key semiconducting, optical, and electronic properties are studied to understand the conduct of LDH materials toward excellent photocatalytic material. The study then deliberates the techniques such as morphological engineering, hybridization with conducting and semiconducting materials, vacancy creation and defect engineering, components tuning, photothermal catalysis, heterojunction, and heterostructural engineering employed for the enrichment of photocatalytic properties. The study also discusses the steps taken to enhance the adsorption of LDHs and coupling of computational and operando techniques toward semiconducting, structural, and optical properties to investigate the best-performing photocatalysts. The study also reviews the recent advancements of LDH for applications toward water splitting and CO2 conversion.