Structural rearrangement by Ni,Cr doping in zinc cobaltite and its influence on supercapacitance

Transitional metal oxides are prevalent in the energy storage devices due to their remarkable electrochemical activity and charge storage capability. In this study, a spinel structured zinc cobaltite (ZnCo₂O₄) is doped with Ni and Cr to form a novel (Ni,Cr:ZnCo₂O₄) electrode material towards supercapacitor (SC) applications. Dopants served as a conductivity booster, particle size reducer and active sites provider benefitting the electrochemical activity. Comparatively, the doped sample delivered a higher capacitance value of 575 Fg^-1 in the potential range of 0–0.6V with 1 M KOH solution as an electrolyte which is higher than that of the pristine material and better cyclic stability is improved from 82.2% to 90.24% for 2000 cycles. The specific capacitance value of 30 Fg^-1 and 73 Fg^-1 at 0.75 Ag^-1 is achieved for the fabricated asymmetric supercapacitor device with Ni,Cr:ZnCo₂O₄ using Cu foil and Ni foam as current collector respectively. The device assembled with doped sample using Ni foam current collector has an energy density of 16.3 WhKg^?1 and a power density of 0.9 KWKg^?1 superseding the performance of the devices constructed with the pristine ZnCo₂O_4. The performance of Ni and Cr doped spinel structured zinc cobaltite device indicates a notable progress towards the direction of better performance supercapacitor applications.     

Green synthesis of LiZnVO4 nanoparticles and its multiple applications towards electrochemical sensor,supercapacitor, humidity sensing,photoluminescence and antioxidant activities

LiZnVO₄ nanoparticles (NPs) were synthesized by a simple combustion method using Hibiscus Rosa Sinensis leaves as a novel fuel and the prepared NPs were characterized using XRD, FT-IR, morphological analysis by SEM and TEM studies, elemental analysis by EDAX and ICP-MS. XRD data of the synthesized NPs were well-matched with the JCPDS number 038–1332 and it confirms the distorted phenacite structure of LiZnVO₄. FT-IR strengthens the bonding of M-M and M–O in LiZnVO₄. Optical characteristics of LiZnVO₄ NPs were studied by photoluminescence (PL) spectroscopy. Vanadate group of the prepared NPs originates a green emission. Examination of latent finger prints (LFP’s) showed a crystal clear patterns under near UV region (365 nm) as they are the prominent techniques in crime investigations. LiZnVO₄ NPs exhibit a strong antioxidant property and act as a good sensor to detect sodium nitrite analyte at extremely low concentrations with limit of detection of 27.5 nM. Three-electrode system supercapacitor device has been fabricated and examined the performances. Specific capacitance of LiZnVO₄ NPs based supercapacitor was found to be 88.7 F/g at a current density of 0.1 mA. Power density (P_d) and energy density (E_d) were found to be 0.51 W/g and 12.3 Wh/Kg, respectively. This device exhibits a stable CV curves up to the scan rate of 10 V/s. Furthermore, LiZnVO₄ NPs acts as an excellent material towards the humidity sensing with a sensitivity factor, sensitivity and limit of detection of 28.0, 0.3 MΩ/%RH and 5%RH, respectively. All the above studies show the diverse potentiality of LiZnVO₄ NPs.

     

Fine-tuning of stannic oxide anodes’ material properties through calcination

Journal of Materials Science: Materials in Electronics - Phase pure stannic oxide (SnO2) is an efficient and reliable anode material for Li ion batteries. Understanding of pure SnO2 phase formation...     

Performance evaluation of high-speed interconnects using dense communication patterns

We study the performance of high-speed interconnects using a set of communication micro-benchmarks. The goal is to identify certain limiting factors and bottlenecks with these interconnects. Our micro-benchmarks are based on dense communication patterns with different communicating partners and varying degrees of these partners. We tested our micro-benchmarks on five platforms: an IBM system of 68-node 16-way Power3, interconnected by a SP switch2; another IBM system of 264-node 4-way Power PC 604e, interconnected by an SP switch; a Compaq cluster of 128-node 4-way ES40/EV67 processor, interconnected by an Quadrics interconnect; an Intel cluster of 16-node dual-CPU Xeon, interconnected by an Quadrics interconnect; and a cluster of 22-node Sun Ultra Sparc, interconnected by an Ethernet network. Our results show many limitations of these networks including the memory contention within a node as the number of communicating processors increased and the limitations of the network interface for communication between multiple processors of different nodes.