Superhydrophilic edge-rich graphene for the simultaneous and disposable sensing of dopamine, ascorbic acid, and uric acid.

A simple and rapid simultaneous sensing strategy of multiple biomarkers is of great importance but challenging in health diagnosis. In this study, a novel free-standing edge-rich graphene film (fs-ERG) was in situ fabricated via a facile chemical vapor deposition route on a porous Si3N4 substrate. The subsequent superhydrophilic modification of the fs-ERG not only makes it maintain the original abundant edge-rich sites, high conductivity, and hierarchical porosity, but also endows it with collective electrochemical characteristics. Thereafter, the superhydrophilic fs-ERG (S-fs-ERG) demonstrated a fast electron-transfer kinetics towards the oxidation of dopamine (DA), ascorbic acid (AA), and uric acid (UA), which promised a sensitive simultaneous electrochemical determination with low detectable limits of 0.1, 2.5 and 0.5 µM, respectively. Furthermore, this sensing electrode displayed high selectivity in the presence of co-existing interferences as well as excellent reproducibility, and thus performed well in DA, AA and UA detection in real samples. These superior sensing performance metrics combined with the low-cost and scalable fabrication of S-fs-ERG based electrodes bode well for their great potential for the simultaneous and disposable sensing of DA, AA and UA in practical application.

All Si3 N4 Nanowires Membrane Based High-Performance Flexible Solid-State Asymmetric Supercapacitor.

Recently, much attention has been drawn in the development of flexible energy storage devices due to the increasing demands for flexible/portable electronic devices with high energy density, low weight, and good flexibility. Herein, vertically oriented graphene nanosheets (VGNs) are in situ fabricated on the surface of free-standing and flexible Si3 N4 nanowires (NWs) membrane by plasma-enhanced chemical vapor deposition (PECVD), which are directly used as flexible nanoscale conductive substrates. NiCo2 O4 hollow nanospheres (HSs) and FeOOH amorphous nanorods (NRs) are finally prepared on Si3 N4NWs @VGNs, which are served as the positive and negative electrodes, respectively. Profiting from the structural merits, the synthesized Si3 N4NWs @VGNs@NiCo2 O4HSs and Si3 N4NWs @VGNs@FeOOHNRs membrane electrodes exhibit remarkable electrochemical performance. Using Si3 N4NWs membrane as the separator, the assembled all Si3 N4NWs membrane-based flexible solid-state asymmetric supercapacitor (ASC) with a wide operating potential window of 1.8 V yields the outstanding energy density of 96.3 Wh kg-1 , excellent cycling performance (91.7% after 6000 cycles), and good mechanical flexibility. More importantly, this work provides a rational design strategy for the preparation of flexible electrode materials and broadens the applications of Si3 N4NWs in the field of energy storage.