Carbon dots as nano-modules for energy conversion and storage

Abstract Materials for energy applications, in particular for conversion and storage of energy, have received an upsurge of interest. Materials of this kind require zero-toxicity, abundance, low-cost, robustness in uses, chemical stability, tunability of properties and ease of preparation to ensure their large scale applications. Carbon dots (C-dots) by virtue of their inherent properties appear to be the most promising material in this regard. C-dots comprising discrete, quasispherical particles with sizes below 10 nm have first been discovered in 2004. Since then research experiences numerous attempts to explore the unique properties of C-dots and to exploit them for energy applications. In this review, we report significant advances of this emerging family of carbon materials in three major fields of energy such as conversion of solar energy into electricity, catalytic splitting of water into hydrogen fuel and storage of electrical energy in supercapacitors and provide an in-depth analysis to highlight their prospects in future applications. At a juncture of global energy crisis, attempts have been made to establish a common venue for researchers working on C-dots for different energy applications. Finally, we address critical insights with the aim towards inspiring more exciting work on C-dots as nano-modules for new energy applications.