Highly crystalline and aromatic nitrogen-doped graphene quantum dots (N-GQDs) which demonstrate unparalleled electrochemical sensing properties toward nitroaromatics were made from a single source, polyaniline (PANI), by a simple hydrothermal synthetic strategy. The higher sensitivity and the effective differentiation between different nitro compounds exhibited by the N-GQD is evidence of its potential as a sensor for nitro compounds, especially the nitroaromatics. The N-GQD modified glassy carbon electrode (N-GQD/GCE) exhibited record sensitivity for 2,4,6-trinitrophenol (TNP) with a limit of detection (LOD) as low as 0.2 ppb (∼200 ng/l or 1 nM), which is the lowest of the reported values, the previous lowest is in micromolar (μM) levels and extended the remarkable sensing property in real water samples as well. The superior and selective sensing behavior of N-GQD toward TNP and other nitroaromatics is assigned to the richly N-doped aromatic structure of the N-GQD from the precursor PANI, which can possibly promote closer and selective molecular interactions with nitroaromatic compounds through ring stacking, π–π, or hydrogen bonding or a combination of these, and the enhanced conductivity and improved electron transfer ability due to the in situ N-doping.

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Many strategies have been adapted to improve the stability of silicon (Si) based anodes, one of the widely studied methods is to make Si-graphene (SiÀ Gr) materials, all have adapted the sandwiched structure of SiÀ Gr or Si-graphene oxide (Si-GO) where Si nanoparticles (NP) are sandwiched between Gr based materials. Herein, we report a simple strategy to achieve SiÀ Gr based anode with a different structure than that of the intercalated structure, which is expected to provide better stability to the SiÀ Gr based anode, i. e. a core-shell structure. This core-shell structure based on a Si-nanographene oxide (Si-nGO) delivers an initial reversible specific capacity of ∼ 2000 mAhg À 1 and stability of � 250 cycles with 80% capacity retention at an active material (AM) AM mass loading of 1.5 mg cm À 2 , and at ∼ 2.0 mg cm À 2 , ∼ 160 cycles stability was achieved, which is one of the best reported values, meanwhile, intercalated Si-graphene oxide (Si-GO) exhibited only < 50 cycles stability at ∼ 2.0 mg cm À 2 mass loading. Higher current rate performance of Si-nGO was ∼ 70% retention of the initial capacity at 5 C, whereas Si-GO retention was < 25% at 5 C. Thus a change in the structure of SiÀ Gr based anode has improved the stability remarkably and shows that it is a promising strategy towards achieving electrode material for advanced lithium-ion batteries (LIBs).