Opportunities and challenges of hydrotalcite-related electrocatalysts for seawater splitting: a systematic perspective from materials synthesis, characterization and application

Extensive chloride ions present in seawater can undergo a competitive reaction with water oxidation on the anode during seawater electrocatalysis. The use of alkaline electrolytes enhances the selectivity of seawater oxidation towards the oxygen evolution reaction rather than the chlorine evolution reaction by increasing the potential gap between the two reactions. Layered double hydroxides (LDHs), also known as hydrotalcites, which can withstand alkaline environments, are suitable for seawater oxidation due to their stability and selectivity. Recent years have witnessed a growing number of publications on LDH-catalyzed seawater splitting. To gain a comprehensive understanding of the current state and challenges of LDH-related electrocatalysts in seawater electrocatalysis, this review conducts a thorough assessment of recent advances in the synthesis, characterization, and electrocatalytic performance of LDH-related materials. First, the review introduces the reaction mechanisms of seawater electrocatalysis over LDH-related materials. The second part presents the common synthetic methods of LDHs, along with the advantages and limitations of each method, as well as various characterization techniques for investigating the structure-activity relationship. Subsequently, the principles for designing LDH-based electrocatalysts and modulating their electrocatalytic activities for seawater splitting are summarized. Furthermore, this review concludes with an analysis of the electrocatalytic performances of LDH derivatives (metal(oxy)hydroxides and phosphides) obtained from LDH precursors. Finally, the challenges and prospects of LDH-related electrocatalysts for seawater electrolysis are discussed.