Effects of stacking layers and different doping elements on the electronic structures and quantum capacitance of graphene: A DFT study

The influence of boron (B), nitrogen (N), oxygen (O), and sulfur (S) doping on enhancing quantum capacitance were investigated through a series of the surface-doped trilayer graphene structures by using density functional theory (DFT) calculations. The quantum capacitance of monolayer models was enhanced through a single doping, a triple doping, and a vacancy defect. Our calculations suggested that the layer interactions within the trilayer models decreased the quantum capacitance but increased the stability of the doped structures. Inter- estingly, in the case of sulfur dopants with significantly larger atomic size than carbon, the stacking layers induced a surface distortion that could avoid the steric clashes with stacking layers and enhanced the stability. In conclusion, this work provided more realistic models of modified carbon-based electrodes for supercapacitors with more accurate information from the combined effects of doping and stacking layers.