Metallenes: Recent Advances and Opportunities in Energy Storage and Conversion Applications

The development of advanced energy storage and conversion technology is a significant global concern, in which the innovation in materials would feature prominently for next-generation energy devices. Graphene, as a typical two-dimensional (2D) material, is acknowledged to have a significant impact on today's energy-storage/conversion evolution. The effectuation for future energy landscape should still enlist alternative 2D materials with high electrochemical activity and energy density. As a group of 2D nanomaterials, metallene is considered as a potential candidate because of its fantastic physicochemical properties. In this Review, the structures, synthesis strategies, and properties of various metallenes are systematically introduced. The research progress and latest achievements in the energy field are reviewed, including Li-/Na-/K-ion batteries, Li–S batteries, solar cells, and typical catalytic processes (i.e., CO2/N2/O2 reduction reaction, hydrogen/oxygen evolution reaction, etc.). Besides, the challenges of miscellaneous energy storage/conversion devices and the advantages of applications of metallenes are discussed and compared. Finally, the development prospects are provided as suggested guidelines for future researches.