Although wide variety of molecular precursors have been used for carbonization-based synthesis of fluorescent carbon nanoparticle, biomolecule-derived carbon nanoparticle with tunable fluorescence is difficult to synthesize. Here, we report a generalized approach for the preparation of fluorescent carbon nanoparticle from various biomolecules, such as lactose, ascorbic acid, tyrosine and sucrose. The method involves controlled carbonization of molecular precursor in ethylene glycol at 190°C in the presence of Na$_3$PO$_4$. The presented synthetic method can produce 20–30 mg of nanoparticles in one batch with fluorescence quantum yield in the range of 1–10% and nanoparticles can be conjugated with primary amine-terminated chemical/biochemical by simple incubation. These fluorescent carbon nanoparticles can be transformed into different nanobioconjugates for various biomedical applications.

The performance of electrochemical water splitting is very much affected by the sluggishness of oxygen evolution reaction (OER) process. Therefore, design and development of low cost, stable and active catalyst for OER process is a challenging issue. In this study we have used cone-shaped pencil graphite (PG), which is commonly used for writing purpose, as anode followed by modification by two-dimensional (2D) nickel sulphide flakes for electrochemical OER in alkaline medium. The dispersed flakes gradually attached to the cone-shaped graphite pencil surface via interaction with exposed graphite sheets along with formation of porous network around the electrode surface via assembly of the flakes. The modified electrocatalyst were well characterized using X-ray diffraction, Raman, field emission scanning electron microscopy, energy dispersive X-ray, inductively coupled plasma atomic emission spectroscopy and electrochemical techniques. We have observed that the electrocatalytic activity and stability of the newly designed anode is far greater than standard IrO$_2$ catalyst-modified PG in alkaline medium and comparable with newly reported Ni-based catalysts modified electrode in literature. The unique shape and porous network facilitate mass diffusion process preventing larger bubble formation. Overall, the approach is very simple and cost effective.