Two-dimensional molybdenum oxides and sulfides for energy systems: Toward efficient and eco-friendly solutions

Two-dimensional (2D) molybdenum-based compounds, including molybdenum oxides and sulfides, offer a promising alternative to traditional materials for energy storage and conversion due to their abundance, less toxicity, high electrical conductivity, chemical stability, and tuneable redox properties. Despite the considerable potential, significant challenges remain in integration of these materials into practical energy devices. Addressing these challenges necessitate a thorough understanding and mitigation of interface-related phenomena such as charge transfer kinetics and ion diffusion limitations to optimize device performance and longevity. This review discusses the key issues and mitigation strategies for molybdenum oxides and sulfides in applications such as supercapacitors, batteries, electrocatalysis, photocatalysis, and solar cells. Additionally, the environmental impact and sustainability of large-scale production processes of these materials that warrant careful considerations, emphasizing resource utilization and waste management has been briefly summarized. Finally, we provide future perspectives and identified challenges, providing insights for further research in this field.