Shuaishuai Zhang,Lingling Zhang,Li Liu,Xiao Wang,Jing Pan,Xiqiang Pan,Han Yu,Shuyan Song
Formaldehyde (HCHO) is a harmful gas of volatile organic compounds (VOCs) and its removal is essential to protect human health. Low-temperature elimination of HCHO by non-noble catalysts is one of the most crucial research topics nowadays. Herein, ultrathin MnO 2 nanosheets grown on Ni-Co layered double hydroxide nanocages (NiCo-LDH@MnO 2 ) were fabricated via a hydrothermal method and subsequently used to eliminate HCHO at low temperature. The NiCo-LDH@MnO 2 -1 catalysts (mass ratio of NiCo-LDH to KMnO 4 of 1:1) performed excellent catalytic activity towards HCHO (100 ppm) at 80 °C. After the fifth cycles, the NiCo-LDH@MnO 2 -1 exhibited excellent stable activity towards the oxidation of HCHO. According to the physicochemical characterization analysis, the enhanced catalytic activity over NiCo-LDH@MnO 2 is attributed to the unique hollow nanocage structure, suitable composition , as well as the synergistic influence of MnO 2 and NiCo-LDH. The results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) presented that the abundant active species (e.g., O 2 − , O − and –OH) can contribute to the adsorption of HCHO on the surface of NiCo-LDH@MnO 2 and promote to oxidize HCHO into the DOM, formate, and carbonate species. Furthermore, NiCo-LDH@MnO 2 displayed good durability for low concentration HCHO (∼9 ppm) at room temperature under 12 h, indicating that the NiCo-LDH@MnO 2 is competitive and inexpensive efficient catalysts for the applications of indoor HCHO purification.
Xiao Li,Yuan-Zhuo Tan,An-Ran Xue,Zhuo Wang,Yuan-Ru Guo,Qing-Jiang Pan
In research out of the sustainable electrochemical energy storage material , NiCo-LDH/MnO 2 composite has been prepared via simple hydrothermal method . The experimental characterizations of XRD , SEM/TEM and XPS have been utilized to explore the structure and morphology of prepared composite. The needle-like MnO 2 was found adhered to NiCo-LDH sheet. The composite's electrochemical properties were evaluated through cyclic voltammetry , galvanostatic charge-discharge and electrochemical impedance spectroscopy . It has been realized that the MnO 2 dosage not only changes the composite's microstructure but also affects its electrochemical properties. The best specific capacitance (2602 F g −1 at a current density of 1 A g −1 ) was achieved for the composite sample with 38% MnO 2 (mass), which is almost two times high from the same composite in previous reports. With the sample, the assembled asymmetric supercapacitor exhibits a remarkable energy density of 19.56 Wh . Kg −1 at 800.29 W Kg −1 . It could be attributed to the synergetic effects of two components as well as their good interfacial coupling. The good electrochemical activity makes our synthesized composite feasible to be applied as electrode material and provides valuable insights for the development of smart capacitors utilizing NiCo-LDH.
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