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Laser reduction of graphene oxide (GO) produces graphene effectively. As a low-power laser source, commercial digital video disc (DVD) drives provide a versatile platform to produce reduced graphene films in designed 2D patterns. However, research on how GO characteristics affect its laser reduction efficiency in DVD drives is rarely conducted. Here, we investigate how heating the GO dispersion affects the photoreduction process of GO films in a LightScribe DVD drive. Without noticeably changing the oxygen content, such mild heat treatment significantly improves GO's absorption in the visible region, resulting in significant enhancement on GO's laser reduction efficiency. We demonstrate that the laser reduction efficiency increases with the increasing treatment time. The enhanced reduction level greatly improves the performance of laser-scribed graphene electrodes in applications such as glucose sensors (with an optimal linear response range up to 2550 μM) and supercapacitors (with an optimal areal capacity of 1.37 mF cm

Monitoring the environmental humidity are of great significance to human comfort and product quality in many fields. However, high performance humidity sensors are difficult to be widely used because of their cost and complex preparation process. It is also highly desirable to develop a facile fabrication method that is capable of producing humidity sensors of customized size, shape, and geometry. Here, using a low power DVD drive, we successfully fabricate a highly sensitivity and low-cost humidity sensor, consisting of laser-scribed graphene (LSG) electrode and graphite oxide (GO) sensing layer. The LSG-GO humidity sensor operates in the relative humidity (RH) range of 19 %–97.4 %, demonstrating high sensitivity (4770.14 pF/% RH), quick response/recovery, and excellent sensing stability. In addition, the possible humidity sensing mechanism is discussed with the help of impedance spectroscopy. These results indicate that the LSG/GO sensor, enabled by the facile fabrication process with low power DVD drives, demonstrates promising potential with broad application prospects.

Flexible solid-state supercapacitors provide a promising energy-storage alternative for the rapidly growing flexible and wearable electronic industry. Further improving device energy density and developing a cheap flexible current collector are two major challenges in pushing the technology forward. In this work, we synthesize a nitrogen-doped graphene/MnO2 nanosheet (NGMn) composite by a simple hydrothermal method. Nitrogen-doped graphene acts as a template to induce the growth of layered δ-MnO2 and improves the electronic conductivity of the composite. The NGMn composite exhibits a large specific capacitance of about 305 F g–1 at a scan rate of 5 mV s–1. We also create a cheap and highly conductive flexible current collector using Scotch tape. Flexible solid-state asymmetric supercapacitors are fabricated with NGMn cathode, activated carbon anode, and PVA–LiCl gel electrolyte. The device can achieve a high operation voltage of 1.8 V and exhibits a maximum energy density of 3.5 mWh cm–3 at a power densit...