Search

Developing an optimized electronic structure of α-NiS electrode material is critical for its high-rate electrochemical performance of quasi-solid-state capacitor. Herein, Al3+ have been doped into α-NiS lattice and the reduced graphene oxide (rGO) is employed to modify Al-doping α-NiS, to alleviate the low-mobility charge of α-NiS. The electronic structure and electrochemical properties of α-NiS hollow spheres induced by Al-doping and rGO modification are investigated, both experimental characterization and theoretical results confirm Al-doping affect the electronic structure and electrochemical performance of α-NiS hollow spheres. In the composite of Al-doping α-NiS and rGO (named as Al x Ni 1-x S/rGO), the doped heteroatom improves the intrinsic electronic structure of α-NiS and the rGO provides a good electric conducting network, leading to an enhanced electrochemical performance of α-NiS as high-rate electrode material. After evaluation, the optimized Al 0.2 Ni 0.8 S/rGO composite shows a superior reversible capacity of 1096 C g−1 at 2 A g−1, and retains a capability of 471 C g−1 at a high-rate of 30 A g−1. Moreover, an asymmetric quasi-solid-state hybrid capacitors assembled by Al 0.2 Ni 0.8 S/rGO and activated carbon presents a high energy density of 30.6 Wh kg−1. This work provides a foundational strategy for the modification of α-NiS through Al-doping and combining with rGO, which has a positive effect on α-NiS electrode material in quasi-solid-state hybrid capacitors. [ABSTRACT FROM AUTHOR]

The electrochemical performance of hybrid capacitors is seriously affected by the slow charging and discharging of the bulk phase. Here, Co-doped amorphous NiMoS4 modified with reduced graphene oxide (rGO) was prepared by a simple one-step hydrothermal method, and the obtained Co-doped NiMoS4/rGO nanocomposite (Ni1−xCoxMoS4/rGO) exhibits a high specific surface area, realizing the redox reaction from the bulk to the surface. Owing to the doping of Co with abundant redox active sites and the support of rGO sheets with high conductivity and a stable structure, the Ni1−xCoxMoS4/rGO anode assembled with an oxidized needle coke (NCO) cathode shows an excellent energy density of 28.9 W h kg−1 at a power density of 968.3 W kg−1. In addition, the hybrid supercapacitor displays a superior cycling performance with a capacity retention of 92.4% after 10 000 cycles. The construction of the Co-doped NiMoS4/rGO nanocomposite provides an effective strategy to boost the activity and stability of amorphous NiMoS4 for high-performance hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

Bisphenol A is a pollutant issued from the degradation of plastics such as polycarbonate and epoxy resins, yet actual bisphenol A monitoring in environmental samples is limited. Here we present the electrochemical detection of bisphenol A with a novel composite, MoS2–CoS2/reduced graphene oxide, obtained by a facile two-step hydrothermal process using MoS2 nanoflowers, CoS2 nano-polyhedrons and reduced graphene oxide. Results show that the linear range of the electrochemical sensor is wider, of 0.02–200 μM, and the detection limit is lower, of 2.5 nM, than actual electrochemical sensors. These findings are explained by good conductivity and the presence of abundant active sites. [ABSTRACT FROM AUTHOR]

Spherical Ni2SnO4 nanoparticles were uniformly loaded on reduced graphene oxide (RGO) sheets via a hydrothermal process. The obtained nickel stannate–reduced graphene oxide (Ni2SnO4–RGO) composite was used as a catalyst for activating persulfate (PS). The heterostructure composed of Ni2SnO4 and RGO prevents both the agglomeration of Ni2SnO4 nanoparticles and the restacking of RGO sheets. The synergy between the two components affords enhanced Ni2SnO4–RGO catalytic activity. Using Ni2SnO4–RGO to activate PS can degrade bisphenol A (BPA) at a faster rate with less PS, in comparison with the most recently reported catalysts. BPA solution (50 mL, 0.10 mM) can be 100% degraded by PS (0.02 g) within 30 min at pH 8 using Ni2SnO4–RGO (0.02 g) as the catalyst. Moreover, the preparation of Ni2SnO4–RGO is simple, inexpensive and environment-friendly. The radical scavenging study indicates that sulfate radicals () and hydroxyl radicals (˙OH) are involved in the oxidation, in which plays a leading role. In addition, Ni2SnO4–RGO retains high catalytic activity after four consecutive cycles, exhibiting greatly enhanced stability in comparison with Ni2SnO4. Besides, the effect of different inorganic anions on the degradation was also explored. [ABSTRACT FROM AUTHOR]

Graphene based copper‐nickel bimetal nanocomposite (Cu3Ni2‐rGO) was prepared via a one‐step solvothermal procedure, in which Ni(OH)2 and Cu(OH)2 were used as precursors. Structural characterization confirms that the as‐prepared Cu3Ni2‐rGO nanocomposite is composed of Cu3Ni2 nanoparticles in the size range of 20–100 nm and the reduced graphene oxide (rGO) sheets. Benefiting from the combination of Cu3Ni2 and rGO, the Cu3Ni2‐rGO nanocomposite exhibits excellent catalytic performance on reducing highly toxic Cr(VI) at room temperature. The reduction of Cr(VI) (40 mL, 100 mg L−1) can be completed within 6 min using Cu3Ni2‐rGO nanocomposite as the catalyst, which is much more efficient than using monometallic nanocomposite containing only Cu or Ni. Moreover, Cu3Ni2‐rGO nanocomposite can be magnetically separated, which enables effective recycle. Besides, Cu3Ni2‐rGO shows good cycling stability. [ABSTRACT FROM AUTHOR]

A ternary reduced graphene oxide based Bi2O2CO3/BiOCl (rBB) composite was prepared for the first time via a facile hydrothermal approach. The composite has a carnation-like morphology and consists of self-assembled nanoplates. Due to the unique structure and synergistic effect existing among reduced graphene oxide (rGO), Bi2O2CO3 and BiOCl nanoplates, the rBB composite exhibits good photocatalytic activity toward the degradation of ciprofloxacin, which is much higher than that of previously reported oxygen-containing bismuth compound photocatalyst. The combination of rGO with Bi2O2CO3/BiOCl greatly improves the visible-light-driven catalytic activity of the composite with the highest degradation efficiency achieved at a rGO content of 1.0 wt%. 83% of the degradation efficiency can be retained after five cycles, and no obvious decrease is observed from the third cycle. Photogenerated holes and hydroxyl radicals are proved to be the major oxidative species in the degradation. The photocatalytic performance of rBB toward degradation of Tetracycline, Methyl Blue and Rhodamine B is also found quite desirable, making rBB a promising broad spectrum photocatalyst. [ABSTRACT FROM AUTHOR]

Nickel phosphate (Ni3(PO4)2) is a promising electrode material for electrochemical capacitors, but the low intrinsic electrical conductivity and poor rate capability of Ni3(PO4)2 are the main challenges. To tackle these problems, amorphous mesoporous Ni3(PO4)2 with a pore diameter of 2–10 nm is grown on reduced graphene oxide (rGO), and a Ni3(PO4)2/rGO composite is obtained via a facile hydrothermal-calcination method in this work. The Ni3(PO4)2/rGO composite calcined at 300 °C (Ni3(PO4)2/rGO-300) possesses a uniform particle size and a high specific surface area of 198.72 m2 g−1. Benefiting from the structural characteristics, the synergistic effect of components and the high specific surface area, the Ni3(PO4)2/rGO-300 composite exhibits an extremely high specific capacitance of 1726 F g−1 at 0.5 A g−1 and an excellent rate capability of 850 F g−1 at 25 A g−1. In addition, the assembled Ni3(PO4)2/rGO-300//activated carbon asymmetric electrochemical capacitor delivers a good energy density of 57.42 W h kg−1 at a power density of 160 W kg−1. Compared with Ni3(PO4)2/rGO composites calcined at other temperatures and other nickel–phosphorus compounds reported in the literature, the Ni3(PO4)2/rGO-300 composite containing amorphous mesoporous Ni3(PO4)2 exhibits superior electrochemical performance, representing a new kind of electrode material for electrochemical capacitors. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries represent one of the next-generation Li-ion batteries. However, the poor conductivity and large volumetric expansion of sulfur result in low rate performance and unfavorable cycle stability. Herein, a laminated structure of sulfur/reduced graphene oxide intercalated by carbon nanotube (CNT-rGO/S) composites was designed and fabricated for the first time to address the issue. The composites prepared via hydrothermal coprecipitation was endowed a perfect crystal and highly integrated structure, which retained a good electrical conductivity and accommodated the sulfur volume expansion due to the sufficient free space between the CNT-intercalated graphene layers. The CNT-rGO/S cathode exhibits a good capacity of 783.3 mAh g −1 at 0.5 C and a desirable cycling stability with 77.2% of the capacity remaining after 1000 cycles even at a rate as high as 5 C, which offers great potential for practical applications in Li-S batteries. [ABSTRACT FROM AUTHOR]