Synthesis and Electronic Modulation of Nanostructured Layered Double Hydroxides for Efficient Electrochemical Oxygen Evolution.

Water electrolysis is considered to be one of the most promising technologies to produce clean fuels. However, its extensive realization critically depends on the progress in cost-effective and high-powered oxygen evolution reaction (OER) electrocatalysts. As a member of the big family of two-dimensional (2D) materials, nanostructured layered double hydroxides (nLDHs) have made significant processes and continuous breakthroughs for OER electrocatalysis. In this review, we discuss the advancements in designing nLDHs for OER in recent years with a unique focus on their electronic modulations and in situ analysis on catalytic processes. We begin with a brief discussion on different synthetic methodologies of nLDHs, including "bottom-up" and "top-down" approaches. Then the general strategies to enhance the catalytic performances of nLDHs reported so far have been summarized, including compositional substitution, heteroatom doping, vacancy engineering, and amorphous/crystalline engineering. Furthermore, we concluded the in situ OER processes and mechanism analysis on engineering efficient nLDHs electrocatalysts. Finally, the research trends, perspectives, and challenges on designing nLDHs have also been carefully outlined. We believe that this progress review may offer enlightening experimental/theoretical guidance for designing highly catalytic active nLDHs and provide new directions to promote their future prosperity for practical utilization in water splitting.