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A two-step laser process consisting of surface treatment and pattern scribing was developed to prepare micro-supercapacitors (MSCs) with high electrochemical performance and structural robustness. First, an ultrathin and uniform graphene oxide (GO) film was deposited onto a copper foil by electrophoretic deposition, after which a laser beam with a wavelength of 450 nm was used to remove the oxygen-containing functional groups and introduce porous structures into the GO film. Subsequently, another laser beam with a wavelength of 1064 nm was used to scribe the film to form finger-patterned electrodes. After being assembled into flexible MSCs, the volume specific capacity of the MSCs reached 1.94 F cm−3, and the power and energy densities reached 4 mW cm−3 and 0.172 mWh cm−3, respectively. After 7000 charge-discharge cycles, the device showed excellent cycling stability with a capacitance retention rate of ∼87.5%. Moreover, the MSCs could be bent into different forms with marginal capacitance loss, confirming their high structural tolerance. Remarkably, the laser-irradiated GO (L -GO) film showed high biosafety toward human empirical cells in the biotoxicity tests, indicating that the devices could be adopted as reliable micro-devices with high biosafety for fabricating wearable electronics on human skin. • Two-step laser treatment was firstly combined to prepare finger patterned flexible MSCs. • The laser treatment could both reduce the GO film and regulate the finger electrodes. • The MSCs demonstrate high energy storage performances and outstanding structural tolerance. • Toxicity tests indicate the MSCs show high biosafety on the human empirical cells. • The MSCs could serve as reliable micro-devices for wearable electronics on human skin. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) porous architecture enables the high exploration of graphene excellent properties, i.e. large surface area and superior conductivity. Additionally, heteroatoms doping can improve the electrocatalytic activity of graphene by creating abundant defective/active sites. To combine the prominent advantages of 3D porous structure and heteroatoms doping, we reported the facile synthesis of 3D phosphorus (P)-doped graphene (3D-PG) and evaluated its potential application in electrochemical H 2 O 2 sensing. As an efficient metal-free electrocatalyst, 3D-PG modified electrode exhibited exceptional sensing performances for sensitive, selective and stable detection of H 2 O 2 , which was ascribed to the synergistic effects of 3D porous structure and P-doping in significantly enhancing the eletrocatalytic activity for H 2 O 2 reduction reaction. More importantly, the 3D-PG based sensor could be used for real-time tracking H 2 O 2 released from living HeLa cells, hence making 3D-PG a potential high-performance electrocatalyst for practical electrochemical sensing. [ABSTRACT FROM AUTHOR]

Exploring highly active, durable and low-cost catalysts toward hydrogen evolution reaction (HER) holds a key to clean energy technologies. Heteroatoms-doped graphene-based materials are emerging as the most promising metal-free HER catalysts, but their catalytic activity remains largely unexplored. Herein, by rationally engineering the macroscopic architecture of graphene and its chemical/defective structures, we developed a three-dimensional (3D), N-doped, plasma-etched graphene (3DNG-P) as a highly active metal-free HER catalyst. The obtained 3DNG-P combined the merits of freestanding 3D porous architecture, high-level N-doping and plasma-induced enriched defects, resulting in a highly enhanced HER activity with a low overpotential of 128 mV at 10 mA cm −2 in acidic medium. Furthermore, the 3DNG-P displayed a favorable HER activity and stability over a wide pH range. The present study thus provides a new methodology for the design of graphene-based metal-free catalysts with high HER performance. [ABSTRACT FROM AUTHOR]