Unleashing the versatility of porous nanoarchitectures: A voyage for sustainable electrocatalytic water splitting

Electrochemical overall water splitting (OWS) has drawn much research fascination as a promising technology for energy conversion to produce clean hydrogen fuel as sustainable chemical resources. However, half reaction of the water splitting reaction, which is oxygen evolution reaction (OER) is the main challenge due to the sluggish kinetics and large thermodynamic barrier. Porous-based materials can markedly enhance the accessibility of active sites, increase specific surface area and optimize the adsorption/desorption of reactants. The enhanced activity arising from the porous materials is attributed to the increase in active sites and improved mass transfer. Herein, the recent research advances made in porous electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and OWS are reviewed. This review focuses on the recent advancements in the synthesis strategies, incorporated with the unique roles of porous structure in electrocatalysts are discussed. For boosting the activity, various emerging modification strategies on porous electrocatalysts, covering structure engineering, phase engineering, defect engineering and strain engineering are presented. This review emphasizes on the synthesis methods, how porous materials improve the performance, mechanistic understanding, integrated experiments, theoretical studies in water splitting, advanced modification strategies and proposed synthesis processes. Specially, the structural-activity relationship gives insights into designing and modifying the porous-based materials with unique properties. Finally, the current science challenges and direction for the future development of porous electrocatalysts are highlighted.