Recent Advances in 0D Ni/Co-based Hollow Electrocatalysts for Electrochemical Water Splitting

Electrochemical water splitting using renewable energy sources has been recognized as a sustainable way to produce hydrogen energy due to the characteristics of low-carbon and no pollution. However, the slow hydrogen/oxygen evolution reactions (HER/OER) seriously hinder the practical application of large-scale water splitting. In this paper, the 0D Ni/Co-based hollow material is discussed in detail because of adjustable morphology, low mass density and abundant active sites, which provides an effective solution for improving the HER/OER reaction kinetics. The synthesis methods of hollow materials, such as hard template, soft template and self-template are introduced. Afterward, catalysts with different structural designs of hollow structures are reviewed, including hollow single-shelled structure, hollow core-shelled structure, hollow double-shelled structure and hollow multi-shelled structure (HoMS) catalysts. Wherein, the research progress of the 0D Ni/Co-based HoMS electrocatalysts in recent years and their prominent performances in water splitting are highlighted. Finally, the challenges and development prospects of designing Ni/Co-based HoMS catalysts in water splitting in the future are discussed.