Jianxiang Wu

Facile synthesis and supercapacitive properties of Zr-metal organic frameworks (UiO-66)

Metal organic frameworks (MOFs), a kind of crystalline porous material, have attracted much attention due to their high surface area and controllable porous structure. In this paper, we present a new synthesis of Zr-based MOFs with high electrochemical performance by a facile synthetic method of changing the reaction temperature and stirring condition. By varying the reaction temperature, different particle sizes and degrees of crystallization can be obtained. This paper focuses on the electrochemical properties of Zr-based MOFs as electrode materials in supercapacitors. The maximum specific capacitance of Zr-MOF1 obtained at 50 °C can reach up to 1144 F g−1 at a scan rate of 5 mV s−1, which is far higher than Zr-MOF2 (811 F g−1), Zr-MOF3 (517 F g−1) and Zr-MOF4(207 F g−1). The results of electrochemical measurements show that the Zr-MOF1 we synthesized has excellent capacitance performance and good cycling stability over 2000 cycles, which makes it a promising supercapacitor electrode material.

Synthesis of nickel oxalate/zeolitic imidazolate framework-67 (NiC2O4/ZIF-67) as a supercapacitor electrode

ZIF-67, NiC2O4·2H2O and NiC2O4/ZIF-67 materials are synthesized by a hydrothermal method. The NiC2O4/ZIF-67 electrode delivers a maximum capacitance of 1019.7 F g−1 at a scan rate of 5 mV s−1, and can maintain the specific capacitance of 73% after 2000 cycles in the 6 M KOH electrolyte.

Synthesis of nickel carbonate hydroxide/zeolitic imidazolate framework-8 as a supercapacitors electrode

The zeolitic imidazolate framework-8 (ZIF-8), nickel carbonate hydroxide (Ni2CO3(OH)2) and Ni2CO3(OH)2/ZIF-8 composite material are synthesized by a typical solvothermal method. In the Ni2CO3(OH)2/ZIF-8 material, the ZIF-8 acts as the host for the growth of Ni2CO3(OH)2. Their structure and surface morphology are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption isotherms. The porous structure combined with Ni2CO3(OH)2 maximizes the utilization of active material, resulting in a high specific capacitance. As electrode materials for supercapacitors, the ZIF-8, Ni2CO3(OH)2 and Ni2CO3(OH)2/ZIF-8 electrodes exhibit a specific capacitance of 140, 668 and 851 F g−1 respectively at a scan rate of 5 mV s−1 and good stability over 5000 cycles. In particular, Ni2CO3(OH)2/ZIF-8 is a promising candidate for the supercapacitor electrode.

Deep oxidation desulfurization with a new imidazole-type acidic ionic liquid polymer

A new solid acidic ionic liquid polymer (PIL) has been synthesized through the copolymerization of acidic ionic liquid oligomers and divinylbenzene (DVB). Its oxidation activities were investigated through oxidizing benzothiophene. The results showed that the PIL was very efficient for oxidizing benzothiophene with its oxidation capacity reaching 95.5% at 323 K for 20 min. The oxidation activities were quite high so that the reactions can occur simultaneously under very mild conditions. The PIL exhibits the advantages of high activities and high stability.

Amorphous nickel–boron and nickel–manganese–boron alloy as electrochemical pseudocapacitor materials

The nanoparticles of amorphous Ni–B and Ni–Mn–B alloys are synthesized and investigated as electrochemical pseudocapacitor materials for potential energy storage applications. The specific capacitance of Ni–B and Ni–Mn–B electrodes are observed to be 562 and 768 F g−1, respectively. The capacitance of Ni–B and Ni–Mn–B retained 65% and 68% of their initial value after a cycle life of 1500 cycles.

An amorphous nickel–cobalt–boron alloy as advanced pseudocapacitor material

The nanoparticles of amorphous nickel–cobalt–boron alloy powder, prepared by chemical reduction, show superior specific capacitance when used as pseudocapacitor material. The amorphous nickel–cobalt–boron alloy exhibits a noticeable pseudocapacitance with 1310 F g−1 at 1.5 A g−1 in the electrolyte of 6 M KOH.

Synthesis and electrochemical characterization of Ni-B/ZIF-8 as electrode materials for supercapacitors

Ni-B/Zeolitic Imidazolate Frameworks-8 (Ni-B/ZIF-8) is synthesized via a series of solvothermal, incipient wetness impregnation and chemical reduction methods. The ZIF-8 serves as the host for the growth of Ni-B forming a Ni-B/ZIF-8 composite. Characterization by X-ray diffraction and Transmission electron microscope reveals the dispersion of Ni-B in ZIF-8. As electrode materials for supercapacitors, ZIF-8, Ni-B and Ni-B/ZIF-8 electrodes exhibit specific capacitances of 147, 563 and 866 F g−1, respectively at a scan rate of 5 mV s−1 and good stability over 500 cycles. In particular, Ni-B/ZIF-8 is a promising material for supercapacitors.

A facile approach to prepare Bi(OH)3 nanoflakes as high-performance pseudocapacitor materials

Bi(OH)3 nanoflakes are prepared by a facile one-step solvothermal approach. The product has a porous structure built up of many interconnected nanoflakes with a thickness of approximately 20 nm. Bi(OH)3 nanoflakes deliver a specific capacitance of 888 F g−1 at a current density of 1 A g−1.