The growing interest in self-clean coatings owes to their low maintenance cost, high durability, and immense potential applications. Such coatings, for instance, may offer useful resistance against fouling, icing, smear, corrosion and possesses oil-water separation capability. Hence, the design and development of self-cleaning materials is an area of significant interest to researchers worldwide. This exploration prospectus critically reviews and highlights various types of self-cleaning surfaces, their applications, working mechanisms, and fabrication techniques used globally. The comprehensive literature study suggests that an extensive study of surface behavior towards water and oil may jointly determine its self-cleaning nature.

Graphene quantum dots (GQDs) are one of the most promising luminescent carbon derived nanomaterials decorated with multiple useful functional groups and remarkable optoelectronic properties. Heteroatom doping of hexagonal carbon sheet of GQDs is an effective strategy to tailor their properties to meet desired application. In this work, sulfur doped GQDs (S-GQDs) were synthesized by simply pyrolyzing citric acid (CA) as a source of carbon and 3-Mercaptopropionic acid as a source of sulfur dopant. The optimal reaction conditions (ratio of the carbon to dopant source, temperature and time of reaction) were obtained while investigating their effect on the quantum yield and fluorescence properties of GQDs and, are hereby, reported for the first time. The as-synthesized S-GQDs were extensively characterized by different analytical techniques such as transmission electron microscopy (TEM), UV–vis Spectroscopy (UV), Fourier transform infrared spectroscopy, photoluminescence (PL) and x-ray Photoelectron Spectroscopy. S-GQDs were found uniform in size (∼4 nm) and spherical in shape with strong blue fluorescence. Further, for in-depth analysis of experimental results and underlying phenomena, theoretical studies based on density functional theory were performed for chemical structure optimization, possible sites of doping and density of states calculation. The synthesized S-GQDs exhibited excellent solubility in water, a stronger fluorescence and desirably higher quantum yield (57.44%) as compared to that of previously reported undoped GQDs. These successfully demonstrated unique and improved properties of S-GQDs present them as a potential candidate for biomedical, optical, electrical and chemical applications.

Pictorial representation of various topics discussed in the review: GQDs synthesis strategies, properties, their regulation through heteroatom doping/surface functionalization, and (bio)analytical sensors (optical, ECL, electrochemical).

This review summarizes the recent progress in synthetic, functional, structural and property control strategies of GQDs and their current potential applications in biomedical and optoelectronic domain.