Enhancement of the supercapacitive properties of laser deposited graphene-based electrodes through carbon nanotube loading and nitrogen doping

• Published in: Physical chemistry chemical physics : PCCP 2019, Vol.21 (45), p.25175-25186
• Main Authors: Pérez del Pino, Ángel, Rodríguez López, Marta, Ramadan, Mohamed Ahmed, García Lebière, Pablo, Logofatu, Constantin, Martínez-Rovira, Immaculada, Yousef, Ibraheem, György, Enikö
• Format: Article
• Language: English
• Subjects: Ammonia; Capacitance; Carbon; Coated electrodes; Doping; Electric charge; Electric double layer; Electrodes; Energy storage; Graphene; Laser deposition; Lasers; Multi wall carbon nanotubes; Nanostructure; Nickel oxides; Nitrogen; Porosity; Pulsed lasers; Redox reactions
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c9cp04237g

Several technological routes are being investigated for improving the energy storage capability and power delivery of electrochemical capacitors. In this work, ternary hybrid electrodes composed of conducting graphene/reduced graphene oxide (rGO), which store charge mainly through electric double-layer mechanisms, covered by NiO nanostructures, for adding pseudocapacitance, were fabricated through a matrix assisted pulsed laser evaporation technique. The incorporation of multiwall carbon nanotubes (MWCNTs) provokes an increase of the porosity and thus, a substantial enhancement of the electrodes' capacitance (from 4 to 20 F cm −3 at 10 mV s −1 ). Volumetric capacitances of 34 F cm −3 were also obtained with electrodes containing just carbon nanotubes coated with NiO nanostructures. Moreover, the use of nitrogen containing precursors (ammonia, urea) for laser-induced N-doping of the nanocarbons also provokes a notable increase of the capacitance. Remarkably, N-containing groups in rGO-MWCNTs mainly add electric double layer charge storage, pointing to an increase of electrode porosity, whereas redox reactions contribute with a minor diffusion fraction. It was also observed that the loading of carbon nanotubes leads to an increase of diffusion-controlled charge storage mechanisms versus capacitive ones in rGO-based electrodes, the opposite effect being observed in graphene electrodes. Laser-deposited graphene-based electrodes for supercapacitors show significant improvement of capacitance after loading with carbon nanotubes and nitrogen doping. Several electrochemical mechanisms act in the charge storage process.