Recent Advances in Complex Hollow Electrocatalysts for Water Splitting

Electrochemical water splitting powered by renewable energy sources has been considered as an attractive hydrogen generation technology with high-purity product and zero carbon emission. However, the efficient realization of large-scale water splitting is severely hampered by the sluggish hydrogen/oxygen evolution reaction (HER/OER). As an important class of functional materials, complex hollow electrocatalysts provide promising solutions to accelerate the HER/OER kinetics owing to their advantageous features, such as abundant exposed active sites, increased contact area between catalysts and electrolyte, and shortened mass/charge transport length. Herein, the recent advances in the development of complex hollow electrocatalysts and their outstanding performances in water splitting are summarized. Beginning with the introduction of reaction mechanisms and design principles, achievements in engineering complex hollow HER/OER electrocatalysts are highlighted with the focus on structural modulation, composition control, and electrocatalytic evaluation. Finally, some present challenges and future perspectives for advanced complex hollow electrocatalysts toward water splitting are further discussed.