Correction: Unique perforated graphene derived from Bougainvillea flowers for high-power supercapacitors: a green approach.

Correction for 'Unique perforated graphene derived from Bougainvillea flowers for high-power supercapacitors: a green approach' by Rajendra P. Panmand et al., Nanoscale, 2017, 9, 4801-4809.

Nanostructured WO3/graphene composites for sensing NO x at room temperature.

WO3 has emerged as an outstanding nanomaterial composite for gas sensing applications. In this paper, we report the synthesis of WO3 using two different capping agents, namely, oxalic acid and citric acid, along with cetyltrimethyl ammonium bromide (CTAB). The effect of capping agent on the morphology of WO3 material was investigated and presented. The WO3 materials were characterized using X-ray diffraction analysis (XRD), field emission transmission electron microscopy (FETEM), field emission scanning electron microscopy (FESEM), particle size distribution (PSD) analysis, and UV-visible spectroscopic analysis. WO3 synthesized using oxalic acid exhibited orthorhombic phase with crystallite size of 10 nm, while WO3 obtained using citric acid shows monoclinic phase with crystallite size of 20 nm. WO3 obtained using both capping agents were used to study their gas sensing characteristics, particularly for NO x gas. The cross sensitivity towards interfering gases and organic vapors such as acetone, ethanol, methanol and triethylamine (TEA) was monitored and explained. Furthermore, the composites of WO3 were prepared with graphene by physical mixing to improve the sensitivity, response and recovery time. The composites were tested for gas sensing at room temperature as well as at 50 °C and 100 °C. The results indicated that the citric acid-assisted WO3 material exhibits better response towards NO x sensing when compared with oxalic acid-assisted WO3. Moreover, the sensitivity of the WO3/graphene nanocomposite was better than that of the pristine WO3 material towards NO x gas. The WO3 composite prepared using citric acid as capping agent and graphene exhibits sensing response and recovery time of 29 and 24 s, respectively.

BiVO4 Fern Architectures: A Competitive Anode for Lithium-Ion Batteries.

The development of high-performance anode materials for lithium-ion batteries (LIBs) is currently subject to much interest. In this study, BiVO4 fern architectures are introduced as a new anode material for LIBs. The BiVO4 fern shows an excellent reversible capacity of 769 mAh g-1 (ultrahigh volumetric capacity of 3984 mAh cm-3 ) at 0.12 A g-1 with large capacity retention. A LIB full cell is then assembled with a BiVO4 fern anode and LiFePO4 (LFP, commercial) as cathode material. The device can achieve a capacity of 140 mAh g-1 at 1C rate, that is, 81 % of the capacity of the cathode and maintained to 104 mAh g-1 at a high rate of 8C, which makes BiVO4 a promising candidate as a high-energy anode material for LIBs.

Unique perforated graphene derived from Bougainvillea flowers for high-power supercapacitors: a green approach.

Herein, we demonstrated a green approach for the synthesis of high surface area (850 m2 g-1) mesoporous perforated graphene (PG) from Bougainvillea flower for the first time using a template free single-step method. The existence of PG was confirmed by XRD, Raman spectroscopy, FESEM, and FETEM. Surprisingly, FETEM clearly showed 5-10 nm perforation on the graphene sheets. More significantly, these mesoporous perforated graphene sheets can be produced in large scale using the present green approach. Considering high surface area and unique perforated graphene architecture, these PGs were studied for supercapacitor applications in detail without any chemical or physical activation. The nanoporosity and high conductivity of PG derived from Bougainvillea flower exhibited excellent supercapacitive performance. According to the supercapacitor study, the synthesized perforated graphene sheets conferred a very high specific capacitance of 458 F g-1 and an energy density of 63.7 Wh kg-1 at the power density of around 273.2 Wh kg-1 in aqueous 1 M Na2SO4. Significantly, the areal capacitance of PG was observed to be very high, i.e. 67.2 mF cm-2. The cyclability study results showed excellent stability of synthesized perforated graphene sheets up to 10 000 cycles. Note that the specific and areal capacitance and the energy density of the synthesized PGs are much higher than the earlier reported values. The high supercapacitive performance may be due to high surface area and mesoporosity of PG. The present approach has a good potential to produce cheaper and high surface area PG. These PGs are good candidates as an anode material in the lithium-ion battery.

Nanostructured CdS sensitized CdWO4 nanorods for hydrogen generation from hydrogen sulfide and dye degradation under sunlight.

In this report, CdS nanoparticles have been grown on the surface of CdWO4 nanorods via an in-situ approach and their high photocatalytic ability toward dye degradation and H2 evolution from H2S splitting under visible light has been demonstrated. The structural and optical properties as well as morphologies with varying amount of CdS to form CdS@CdWO4 have been investigated. Elemental mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the sensitization of CdWO4 nanorods by CdS nanoparticles. A decrease in the PL emission of CdWO4 was observed with increasing amount of CdS nanoparticles loading possibly due to the formation of trap states. Considering the band gap in visible region, the photocatalytic study has been performed for H2 production from H2S and dye degradation under natural sunlight. The steady evolution of H2 was observed from an aqueous H2S solution even without noble metal. Moreover, the rate of photocatalytic H2 evolution over CdS modified CdWO4 is ca. 5.6 times higher than that of sole CdWO4 under visible light. CdS modified CdWO4 showed a good ability toward the photo-degradation of methylene Blue. The rate of dye degradation over CdS modified CdWO4 is ca. 7.4 times higher than that of pristine CdWO4 under natural sunlight. With increase in amount of CdS nanoparticle loading on CdWO4 nanorods the hydrogen generation was observed to be decreased where as dye degradation rate is increased. Such nano-heterostructures may have potential in other photocatalytic reactions.

Determination of trace concentrations of elements in high purity tellurium by radio frequency glow discharge optical emission spectrometer (RF-GDOES).

A method was established for the determination of trace impurities in high purity tellurium (Te) 99.9999 (6N) by radio frequency glow discharge optical emission spectrometry (RF-GDOES). The optimized parameters are power, argon pressure, pre-integration time, analysis time and selection of wavelength. Nine elements Se, Ca, Mg, Si, Fe, Cr, Cu, Ni and Pb were analysed in 6N Te, out of which only three elemental peaks (Se, Ca, and Mg) were detected and the remaining six elements ( Si, Fe, Cr, Cu, Ni and Pb) were below detection levels. Finally, the method was evaluated by the analysis of the above traces using inductively coupled plasma mass spectrometry (ICP-MS) and was found to be satisfactory. The detection limits for most of the elements were below 10 ng/g and R.S.D. was around 10%, which indicated that this method could fully satisfy the requirements for the trace analysis in high purity Te metal.