A review of the improved electrochemical property achieved by the incorporation of transition metal-based quantum dots applied in supercapacitors

Owing to their quantum confinement and edge effects, quantum dots exhibit exceptional properties, including an enlarged specific surface area, high surface-to-volume ratios and abundant active sites. These attributes render them applicable in diverse energy-related domains such as solar cells, catalysis, batteries, and supercapacitors. Notably, quantum dots based on transition metals exhibit promising potential in enhancing electrochemical performance within the realm of supercapacitors. By inheriting high redox activity from transition metals, these quantum dots successfully address the limitations associated with low conductivity, cycling stability, and material utilization inherent in conventional supercapacitor materials. This paper systematically reviews recent advancements in the utilization of various transition metal-based quantum dots in supercapacitors, encompassing pristine transition metals, transition metal oxides, transition metal sulfides, and transition metal hydroxides quantum dots. Emphasis is placed on elucidating the outstanding electrochemical properties and underlying mechanisms of action facilitated by transition metal-based quantum dots in the context of supercapacitors. Subsequently, detailed insights into the synthesis and assembly methods of quantum dots are provided. Finally, a thorough discussion on the significant challenges encountered by quantum dots in super- capacitors, along with proposed future research directions, is presented.