Sulphur-doped carbon-based materials have attracted a great deal of interest because of their important applications in the fields of oxygen reduction reactions, hydrogen storage, supercapacitors, photocatalysts and lithium ion batteries. Here, we report a new member of sulphur-doped carbon-based materials, i.e. sulphur doped graphene quantum dots (S-GQDs). The S-GQDs were prepared by a hydrothermal method using fructose and sulphuric acid as source materials. Absorption and photoluminescence investigations show that inter-band crossings are responsible for the observed multiple emission peaks. The incorporation of ∼1 at% of S into the quantum dots can effectively modify the electronic structure of the S-GQDs by introducing S-related energy levels between π and π* of C. The additional energy levels in the S-GQDs lead to efficient and multiple emission peaks.

Multicolour emission is realized in chlorine-doped GQDs (Cl-GQDs) prepared by a facile hydrothermal method using fructose and hydrochloric acid as source materials. The average diameter of a Cl-GQD is about 5.4 nm with 2 at.% Cl. The emission colour of the Cl-GQDs can be tuned successively from blue to white, orange, green and red simply by varying the excitation wavelength between 300 and 600 nm. The multicolour emission from the Cl-GQDs can be attributed to Cl doping, which introduces additional energy levels between C π and C π*. The multicolour Cl-GQDs should find applications in bioimaging and optoelectronic devices.

The effect of carbon supports on the electrochemical performance of MoS₂ nanosheets for supercapacitor applications was investigated.

The PCE value of the NiCoSe₂-150-based DSSC is 8.76%, which is higher than that of DSSCs based on Pt (8.22%).

CoMn₂O₄@Co₃O₄ core/shell arrays on Ni foam exhibit outstanding electrochemical performance for asymmetric supercapacitors with respect to high specific capacitance and high cycling stability.