Unraveling quantum capacitance of black phosphorene by the doping of non-metals for energy storage applications using DFT method

Supercapacitor plays a pivotal role as energy storage devices in the context of eliminating energy resources. Black Phosphorene (BP) is highly regarded as a potential electrode for supercapacitor (SC) because of its outstanding properties, including excellent carrier mobility and unique electronic properties. In this research work, the monolayer of BP and bilayer of BP (BP/BP) structure is investigated by using DFT. Moreover, the effect of doping and co-doping of non-metal (oxygen, nitrogen) in the mono- and bi-layer was also investigated to increase their performance by modulating the charge storage, and electronic properties of BP. The structural properties, density of states, quantum capacitance, surface charge density, bader charge analysis, isosurface charge density difference, integrated charge density of monolayer and bilayer are studied. The density functional theory (DFT) is used to calculate all above mention properties. DFT-D3 method with Becke-Johnson damping function is used as dispersion correction factor for all the calculations of bilayer. The calculated results find that bilayer structure gives better results as compared to monolayer structure. In this work, results also revealed that doping of oxygen and nitrogen atom significantly enhance the C_Q and Q of mono- and bi-layer structure. For aqueous system, all the composites exhibited asymmetrical behavior except BP/BP bilayer. BP-N/BP-N (1369.8µC/cm²), and BP-O/BP-O (-1298.1µC/cm²) bilayer structure are best for anode and cathode material. In case of ionic/organic system, all composites showed asymmetrical behavior. BP-O/BP-O (-6053.5µC/cm²), and BP-N/BP-N (9329.8µC/cm²) bilayer structure is best cathode and anode material.