No abstract

Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.

Synthesis of nanocrystals with exposed high-energy facets is a well-known challenge in many fields of science and technology. The higher reactivity of these facets simultaneously makes them desirable catalysts for sluggish chemical reactions and leads to their small populations in an equilibrated crystal. Using anatase TiO 2 as an example, we demonstrate a facile approach for creating high surface area, stable nanosheets comprised of nearly 100% exposed (001) facets. Our approach relies on spontaneous assembly of the nanosheets into three-dimensional, hierarchical spheres that stabilizes them from collapse. We show that the high surface density of exposed TiO 2 (001) facets leads to fast lithium insertion/deinsertion processes in batteries that mimic features seen in high power electrochemical capacitors.2