Ultrafast photo-annealed carbon-coated SiO2 sphere electrodes for NO2 gas sensing

There is great interest in carbon-based printed electronics as a promising technology to achieve lighter, thinner and flexible electronic devices at low-costs. Despite the surge of enthusiasm in this area, research advances in printed electronics are not yet able to realize diverse carbon structures yet. This is due to the limitations in conventional solution-based printing methods (e.g., inkjet printing, roll-to-roll, screen printing). Processes such as polymer phase-inversion offer one possibility but a much faster and efficient method should be devised for reliable production. Here, we demonstrate laser printing combined with intense pulsed-light (IPL) annealing as a novel and efficient technique which can form inter-connected carbon spheres electrode on flexible polymer substrate. Our observations show that the printed patterns from a laser printer consist of a solid-state polymer matrix with inorganic nanoparticles randomly embedded inside. Through ultrafast (5 ms) IPL treatment, core/shell type nanosphere arrays of carbon-coated SiO2 were successfully fabricated, which could be used as a functional platform for highly selective NO2 gas sensing.