Influence of heteroatom doping on the quantum capacitance of phosphorene supercapacitors

The focus is on new energy storage technologies that can serve as a reliable replacement for lithium-ion batteries and other traditional energy storage devices. In this context, 2D materials-based supercapacitors have recently drawn a lot of attention due to the plethora of available layered materials as well as their enhanced electrochemical performance. Using first-principles density functional theory (DFT) calculations, this study investigates the modulation of the quantum capacitance of monolayer phosphorene in the presence of a semi-metal (Si), a reactive non-metal (S) and two transition metals (Ti, Ni) dopants and compares it to the pristine monolayer phosphorene. The binding energies of the doped systems depict structural stability for all doped systems. The most stable system is discovered to be Si-doped phosphorene with binding energy of −7.44 eV/atom. The band structure and density of states computations are used to study the electronic characteristics of doped and undoped monolayer phosphorene lattices. The Ti doped system shows the highest value of quantum capacitance (92.1 μF/cm 2 at 0.4 V). The results portrayed through this study provide a detailed understanding to enhance the quantum capacitance of phosphorene and shows a promising pathway for phosphorene-based electrode materials for supercapacitors, which are assessed using first-principles density-functional theory calculations. • First computational study on the quantum capacitance of doped phosphorene structures. • Insights on the effects of dopants on the quantum capacitance of phosphorene. • Titanium-doped structures exhibited the maximum quantum capacitance.