Band 6, Heft 1-2 -

The carbon sphere (CS)@nickel cobalt sulfide core-shell nanocomposite at five different mole ratios have been synthesized by a facile low-temperature water-bath method without any thermal treatment. The XRD results on CS, NiCo 2 S 4 and its ternary complexation confirms nanocomposite formation which matches with the cubic structure. The FTIR confirms the complexation of CS and metal-sulfide core-shell. TEM morphology shows CS at NiCo 2 S 4 forming a core-shell which appears as interlinked bunch of grapes. The BET surface analysis observes the high surface area for the core-shell. The XPS studies confirm the elemental presence and valence states of metal composition of the core-shell. Electrochemical studies on the pure NiCo 2 S 4 and CS@NiCo 2 S 4 have shown that CS@NiCo 2 S 4 in 1:1 ratio (scn2) only exhibits higher specific capacitance of 838 F g −1 at 1 A g −1 with capacity retention of 89 % for 5000 cycles than other mole ratios. Using this scn2, asymmetric supercapacitor (ASC) device fabrication has been studied. The electrochemical studies on ASC reveal high energy density of 101 Wh kg −1 with the power density of 6.3 k W kg −1 , and having good cycling stability with 92 % of capacitance retention even after 3000 cycles at 20 A g −1 .

A completely energy autarkic design for a classroom response system is presented. Maloperation by the user is prevented with the chosen design (no unnecessary buttons and switches). Electronic classroom response systems have been around for quite a while and do exist in various forms and flavors. Most commercially available solutions, however, have several disadvantages. The new device is an easy-to-use, robust form of a clicker, which takes its energy from the click itself, due to a very low-power system using only an energy of around 15 μ J per wireless telegram transmitted from each student to the teacher’s computer. The described system serves as both, a method to check students’ progress in any field of lecturing as well as a tool that (by its development) instructs students in the field of “Energy Harvesting for Small Wireless Devices”. The system also contributes to raising awareness of the material and energy balance in today’s electronics.

Organic solar cells deal with small organic molecules for absorption of light at low cost and high efficiency. In this paper, we have analyzed the photovoltaic (PV) characteristics of double heterojunction solar cell that consists of copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI) thin films. Here, CuPc and PTCBI layers are combined by an interfacial layer consisting of nanoscale dots. Different plasmonic materials (i. e. Ag, Au, and graphene) are selected as alternative nanoscale dot layer to examine their effect on solar cell performance. Further, the solar cell performance is also examined via variation in active layer thickness. The choice of interfacial layer material and variation in active layer thickness offer grounds for future efficient PV cells.

Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transforming electrical signals to mechanical signals. In this paper, the use of MEMS devices as a method for harvesting waste heat is explored. A background for the technology and methods is discussed and a method proposed for a working device based upon a thermally heated bimorph actuated by waste radiation alone is investigated. A chopper interrupts the radiant energy inducing an oscillation in the bimorph temperature and thus creates a mechanical motion which can be taken advantage of using piezoelectric materials. Difficulties in harvesting radiant energy with this method are highlighted and suggestions for non-passive energy generation are made based on the outlined principles.