A versatile method based on the matrix assisted pulsed laser evaporation (MAPLE) technique was used for the fabrication of graphene-based electrodes for application in supercapacitors. The simultaneous deposition and chemical transformation of graphene oxide (GO) and GO–NiO nanoparticles was attained by including nitrogen-containing chemically reactive compounds (ammonia, urea and melamine) in aqueous MAPLE targets. Morphological analyses reveal the formation of hundreds of nanometres to tens of micrometres thick porous films on both plastic and metallic flexible substrates. Structural and compositional studies, carried out by transmission electron microscopy, and Raman and X-ray photoelectron spectroscopies, disclose significant deoxidation and nitrogen doping of the GO material. The electrodes reveal remarkable electrochemical performance, showing a maximum volumetric capacitance of 350 F cm⁻³ (9 mF cm⁻² areal capacitance) in aqueous electrolyte. Symmetric supercapacitors fabricated with these electrodes reveal excellent long-term stability at high specific intensities. From the obtained results, it can be asserted that the reactive inverse MAPLE method stands out as a promising technology not only for the adaptable fabrication of flexible graphene-based composite electrodes but also for a wide variety of advanced functional materials for diverse applications.

Graphene nano-walls (GNWs) are promising materials that can be used as an electrode in electrochemical devices. We have grown GNWs by inductively-coupled plasma-enhanced chemical vapor deposition on stainless steel (AISI304) substrate. In order to enhance the super-capacitive properties of the electrodes, we have deposited a thin layer of MnO₂ by electrodeposition method. We studied the effect of annealing temperature on the electrochemical properties of the samples between 70 °C and 600 °C. Best performance for supercapacitor applications was obtained after annealing at 70 °C with a specific capacitance of 104 F·g⁻¹ at 150 mV·s⁻¹ and a cycling stability of more than 14k cycles with excellent coulombic efficiency and 73% capacitance retention. Electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements reveal fast proton diffusion (1.3 × 10⁻¹³ cm²·s⁻¹) and surface redox reaction after annealing at 70 °C.

A versatile method is explored to decorate vertically aligned multi-walled carbon nanotubes (VACNTs) with NiO nanostructures. Multi-walled VACNTs are grown by plasma-enhanced chemical vapor deposition and coated with NiO nanoparticles (NPs) by drop casting. After that, the system is submitted to nanosecond pulsed UV laser irradiation in atmospheric environment. Laser irradiation provokes rapid heating–melting–cooling processes which lead to the recrystallization of NiO NPs on the outer walls of VACNTs. In this way, and depending on the laser fluence and the number of accumulated pulses, different nano-architectures such as continuous NiO coatings and spiny features on VACNTs are obtained. High-resolution scanning and transmission electron microscopies and Raman spectroscopy, corroborated with photothermal simulations, suggest that the grown nanostructures are mainly created by the laser-induced high temperatures (photothermal mechanisms). However, the observed reconstruction of the outer graphitic shells of VACNTs point to the catalytic action of NiO NPs, probably induced by the direct action of laser radiation.