Quantum capacitance engineering in homo and hetero bilayer structure of blue phosphorene electrode for supercapacitor applications: Using ab-initio calculation

In this work, the structural, electronic properties, quantum capacitance (CQ), surface charge density (Q), isosurface charge density difference and bader charge analysis of homo- and hetero-bilayer structures of BP, ZnO, GaN and hexagonal boron nitride forming supercapacitor electrode are studied. The effect of doping of Cu-atom in the substrate of homo- and hetero-bilayer was also investigated to modulate the charge storage and electronic properties of BP. All the properties are calculated theoretically using density functional theory (DFT). DFT-D3 method with the Becke-Johnson damping function is used as the dispersion correction factor for all the calculations. The calculated results find that hetero-bilayer structure gives better results as compared to homo-bilayer structure. In this work, results also revealed that doping of transition atoms significantly enhances the CQand Q of hetero-bilayer structure. For the aqueous system, all the bilayers exhibited asymmetrical behaviour except the BP-ZnO hetero-bilayer. Cu-doped BP-ZnO (1554.8μC/cm2), and Cu-doped BP-HBN (−1438.4μC/cm2) hetero-bilayer structure is best for anode and cathode material. In the case of ionic/organic systems, all bilayers showed asymmetrical behaviour. Cu-doped BP-ZnO (−5250 μC/cm2), and BP-GaN (3660μC/cm2) hetero-bilayer structure is the best cathode and anode material.