Graphene quantum dots (GQDs) are synthesized from bio-waste and are further modified to produce amine-terminated GQDs (Am-GQDs) which have higher dispersibility and photoluminescence intensity than those of GQDs. A strong fluorescence quenching of Am-GQDs (switch-off) is observed for a number of metal ions, but only for the Ag(+) ions is the original fluorescence regenerated (switch-on) upon addition of L-cysteine.

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Graphical abstractSeveral organic precursors have been used to fabricate Fe-based catalysts using sacrificial support method. Those catalysts were then included in air breathing cathodes for microbial fuel cells working at neutral environment. Electrochemical performances and surface chemistry were measured and related.

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Blue fluorescent graphene quantum dots (GQDs) are synthesized from small haloaromatic molecules by laser photochemistry. The process involves a bottom‐up photochemical stitching mechanism of the free radicals generated by irradiation of ultraviolet photons (λ = 248 nm) on o‐dichlorobenzene. The GQDs are further demonstrated to be of importance as fluorescent nanoprobes in bioimaging of cells.