A poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hydrogel is prepared by thermal treatment of a commercial PEDOT:PSS (PH1000) suspension in 0.1 mol L sulfuric acid followed by partially removing its PSS component with concentrated sulfuric acid. This hydrogel has a low solid content of 4% (by weight) and an extremely high conductivity of 880 S m . It can be fabricated into different shapes such as films, fibers, and columns with arbitrary sizes for practical applications. A highly conductive and mechanically strong porous fiber is prepared by drying PEDOT:PSS hydrogel fiber to fabricate a current-collector-free solid-state flexible supercapacitor. This fiber supercapacitor delivers a volumetric capacitance as high as 202 F cm at 0.54 A cm with an extraordinary high-rate performance. It also shows excellent electrochemical stability and high flexibility, promising for the application as wearable energy-storage devices.

Base-induced graphene oxide (GO) liquid crystals form a highly ordered texture. This microstructure can be inherited by graphene foams prepared by hydrothermal reduction, showing a long-range ordered microstructure of graphene sheets in 3D. This provides an insightful understanding into the supramolecular chemistry of GO sheets.

Graphene oxide membranes (GOMs) are mechanically stable in various organic solvents, and their nanochannels can be narrowed by thermal annealing or widened by solvation. Therefore, the semipermeability of GOMs can be easily modulated, and they can be used as "multipurpose membranes" for molecular sieving in organic media.

An electrochemical capacitor (EC) with H2SO4 treated PEDOT:PSS/graphite foil electrodes exhibited the highest areal and volumetric specific capacitances among the reported ECs with phase angles larger than −80° at 120 Hz.

Conducting polymers (CPs) have been widely applied as electrocatalysts and photocatalysts in energy-related systems, sensors, and environmental protection. This is mainly due to their promising catalytic activities, high conductivities, and unique electrochemical and optical properties. Furthermore, CPs can be cheaply and conveniently prepared in large scale via chemical or electrochemical approaches. In this Perspective, we review the recent advancements on the synthesis and applications of CP-based inherent and composite catalysts and CP-derived heteroatom-doped carbon catalysts. The mechanisms of catalysis will be introduced, and the challenges of developing CP-based catalysts with practical importance will be discussed.

The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering are usually the largest components in the electronic circuits because of their low specific capacitances and bulky sizes. Herein, nitrogen-doped holey graphene (NHG) films were prepared by thermal annealing the composite films of polyvinylpyrrolidone (PVP), graphene oxide (GO), and ferric oxide (Fe2O3) nanorods followed by chemical etching with hydrochloride acid. The typical electrochemical capacitor with NHG electrodes exhibited high areal and volumetric specific capacitances of 478 μF cm(-2) and 1.2 F cm(-3) at 120 Hz, ultrafast frequency response with a phase angle of -81.2° and a resistor-capacitor time constant of 203 μs at 120 Hz, as well as excellent cycling stability. Thus, it is promising to replace conventional AEC for AC line-filtering in miniaturized electronics.

window (around 3 V) are more favorable for practical applications. Up to date, only an ultrafast OEC based on CNT films has been reported in literature. [10] However, the preparation of CNT electrodes involved complicated processes of vacuum filtration and expensive chemical vapor deposition. Therefore, a facile and scalable method to fabricate OECs with excellent AC line-filtering performances still remains as a challenge.In this paper, we report the fabrication of OECs based on electrochemically reduced less defective graphene oxide (ERLGO) films with oriented 3D interconnected porous structures. For optimizing the performance of ERLGO electrode, LGO sheets with a small average size of 0.7 µm (sLGO) were used and the resulting ERsLGO electrode was further deeply reduced in an organic electrolyte. The typical OEC exhibited high areal specific energy density, excellent electrochemical stability, and superior rate capability, promising for AC line filtering. These OECs can also be connected in series or parallel to meet various demands in industrial levels. Results and DiscussionThe graphene electrode (Figure 1a) was prepared by electrochemical reduction of LGO or sLGO sheets in their aqueous dispersion (3 mg mL −1 ) at −1.1 V for 4 s, then further deeply reduced in an organic electrolyte at −2.0 V for 20 s. The organic electrolyte was 1 mol L −1 acetonitrile (AN) solution of tetraethylammonium-tetrafluoroborate (TEABF 4 ). LGO sheets were prepared by oxidation of graphite flakes at a low temperature of 0 °C. [19] They have an average lateral dimension of 7 µm (Figure 1b, Figure S1, Supporting Information). During the electrodeposition process, LGO sheets were selfassembled onto the surface of substrate electrode upon the driving by directional electric field. [20] Simultaneously, they were electrochemically reduced to ERLGO sheets to form a porous network because of π-π stacking and hydrophobic interactions. However, the ERLGO electrode has a relatively disordered porous structure ( Figure S2, Supporting Information) because of the steric obstacles of these large graphene sheets during their self-assembling process. Therefore, we pulverized LGO sheets in their aqueous dispersion by sonication, significantly reducing their average size to around 0.7 µm (Figure 1c, Less-defective graphene oxide sheets with a small average size of 0.7 µm are electrochemically reduced to form a hydrogel film with highly oriented porous structure. It is applied as the electrode of organic electrochemical capacitor (OEC) after solvent change with organic electrolyte and deep reduction in this organic medium. At 120 Hz, the typical OEC exhibits a high areal specific energy density of 472 µF V 2 cm −2 with a wide workable voltage window of 2.5 V, a phase angle of −80.5°, a resistor-capacitor time constant (τ RC ) of 0.219 ms, and an excellent electrochemical stability. Thus, it is promising to replace aluminum electrolytic capacitors for AC line filtering. Furthermore, two identical OECs connected in series keep the performance of single...

Reduced graphene oxide (rGO) sheets were self-assembled onto the surfaces of electrospun polymer nanofibers to form an ultrathin coating. These rGO/polymer composite nanofibers were used to fabricate nitrogen dioxide (NO2) sensor. This sensor can be performed at room temperature, and it exhibited a high sensitivity of 1.03 ppm(-1) with excellent selectivity and good reversibility. Furthermore, the limit of detection was experimentally measured to be as low as 150 ppb, and this value is much lower than the threshold exposure limit proposed by American Conference of Governmental Industrial Hygienists (200 ppb).