High-performance stretchable and wearable electronic skins (E-skins) with high sensitivity and a large sensing range are urgently required with the rapid development of the Internet of things and artificial intelligence. Herein, a reduced graphene oxide (rGO)/polyaniline wrapped sponge is prepared via rGO coating and the in situ synthesis of polyaniline nanowires (PANI NWs) on the backbones of sponge for the fabrication of pressure sensors. From the as-prepared flexible sensor, tunable sensitivity (0.042 to 0.152 kPa-1), wide working range (0-27 kPa), fast response (∼96 ms), high current output (∼300 μA at 1 V), frequency-dependent performance reliable repeatability (∼9000 cycle) and stable signal waveform output can be readily obtained. In addition to tiny physiological activities (voice recognition, swallowing, mouth opening, blowing and breath), robust human motions (finger bending, elbow movement and knee squatting-arising) can also be detected in real-time by the flexible sensors based on rGO/polyaniline wrapped sponge. All the results demonstrate that the flexible pressure sensor based on the functional-sponge is a promising candidate for healthcare monitoring and wearable circuitry in artificial intelligence.
Multifunctional microelectronic components featuring large stretchability, high sensitivity, high signal-to-noise ratio (SNR), and broad sensing range have attracted a huge surge of interest with the fast developing epidermal electronic systems. Here, the epidermal sensors based on all-carbon collaborative percolation network are demonstrated, which consist 3D graphene foam and carbon nanotubes (CNTs) obtained by two-step chemical vapor deposition processes. The nanoscaled CNT networks largely enhance the stretchability and SNR of the 3D microarchitectural graphene foams, endowing the strain sensor with a gauge factor as high as 35, a wide reliable sensing range up to 85%, and excellent cyclic stability (>5000 cycles). The flexible and reversible strain sensor can be easily mounted on human skin as a wearable electronic device for real-time and high accuracy detecting of electrophysiological stimuli and even for acoustic vibration recognition. The rationally designed all-carbon nanoarchitectures are scalable, low cost, and promising in practical applications requiring extraordinary stretchability and ultrahigh SNRs.
Developing highly active electrocatalysts with low cost and high efficiency for oxygen evolution reactions (OER) is important for the practical implementations of hydrogen energy. Here, we report a Zn-doped CoSe nanosheets grown on free-standing carbon fabric collector (CFC), which was synthesized by using a metal-organic framework (MOF) as precursor and followed by a selenylation process. Importantly, the Zn-doped CoSe/CFC electrode exhibited an obviously enhanced catalytic activity for OER in 1 M KOH aqueous solution compared with CoSe/CFC, showing a small overpotential of 356 mV for a current density of 10 mA cm, a small Tafel slope of 88 mV dec, and an excellent stability. The robust and free-standing electrode shows great potential as an economic catalyst for OER applications.
Transition metal
sulfides with designed nanostructure have attracted significant research
interest as electrode materials for supercapacitors. In this work,
core–shell structured Co9S8@N–C@MoS2 nanocubes have been successfully fabricated through a sulfuration
process based on ZIF-67 precursor. Due to improved electrical conductivity
and large surface area, Co9S8@N–C@MoS2 nanocubes with core–shell heterostructure exhibit
better electrochemical performance in supercapacitors compared with
Co9S8. Moreover, the morphology of core–shell
structured Co9S8@N–C@MoS2 nanocubes
can be well-adjusted by tuning the ratio between Co9S8 and MoS2. The homogeneous core–shell structured
Co9S8@N–C@MoS2 nanocubes (S-3)
can be obtained with the mass ratio of Na2MoO4·2H2O and CH4N2S at 1:2. And
the obtained core–shell structured S-3 delivers a high specific
capacitance of 410.0 F g–1 at the current density
of 10.0 A g–1 after 20000 cycles with excellent
cycling stability (101.7% of the initial value). The excellent electrochemical
property is mainly due to the unique structure which induces synergistic
effects between Co9S8 and MoS2.
Electrochemical water-splitting with non-noble metal catalysts provides an eco-friendly strategy for renewable production of hydrogen. In this study, the MoP@C@reduced graphene oxide (rGO) composite was prepared via mild reactions through a chemical bath and postannealing process. With the assistance of citric acid, the MoP@C@rGO composite containing ultrafine MoP nanoparticles with a size of 3 nm anchored on two-dimensional C/rGO nanosheets has been obtained. The chelation effect with citric acid and the merits of rGO not only lead to affordable active sites but also improved the electrical conductivity and stability at the same time. Serving as the hydrogen evolution reaction (HER) electrocatalyst, the MoP@C@rGO composite presents a small overpotential of 168.9 mV at 10 mA cm. It has superior durability when compared to samples of pure MoP, MoP@C, and MoP@rGO. The relative high activity and stable performance as well as the simple preparation process make the MoP@C@rGO composite a promising HER electrocatalyst.
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