Materials for Renewable and Sustainable Energy

Suriwong, Tawat; Bunmephiphit, Chanon; Wamae, Warisa; Banthuek, Sathit

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0121-0

This study investigates the influence of Ni–Al coating thickness on the spectral selectivity and thermal performance of a parabolic trough collector (PTC). Three thicknesses of Ni–Al coating for use as solar absorber material were successfully prepared on the outer surface of a stainless steel 316L (SS) tube by flame spray. The phase, morphology, and reflectance (R) of the Ni–Al coatings were characterized using several techniques. The PTC and solar receiver tube were specially designed and constructed for observing the collector thermal performance by following ASHRAE 93-1986. Looking at the results, the actual average thicknesses of the three Ni–Al coatings turn out to be 195, 215, and 299 μm. The morphology and chemical composition of all three thicknesses are similar. The chemical composition in the cross-sectional view exhibits non-uniform distribution. The three thicknesses of the coating are composed of NiO and Al2O3 phases, which also corresponded to the results of SEM–EDX mapping. The differences in a solar absorptance (α) of the three thicknesses of Ni–Al coating are not statistically significant, with an average α value of 0.74–0.75. However, there are differences in thermal efficiency of the PTC depending on the thickness of the Ni–Al coating. Of the three samples, the thickest one (299 µm) demonstrates the highest ability to convert solar radiation into thermal energy.

Majewski, Artur; Dhir, Aman

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0123-y

In this paper, the behaviour of silver as cathode conductive material, interconnect wire, and sealing for anode lead connection for microtubular solid oxide fuel cells (µSOFC) is reported. The changes in silver morphology are examined by scanning electron microscopy on cells that had been operated under reformed methane. It is found that using silver in an solid oxide fuel cell (SOFC) stack can improve the cell performance. However, it is also concluded that silver may be responsible for cell degradation. This report brings together and explains all the known problems with application of silver for SOFCs. The results show that silver is unstable in interconnect and in cathode environments. It is found that the process of cell passivation/activation promotes silver migration. The difference in thermal expansion of silver and sealant results in damage to the glass. It is concluded that when silver is exposed to a dual atmosphere condition, high levels of porosity formation is seen in the dense silver interconnect. The relevance of application of silver in SOFC stacks is discussed.

Thakur, A.; Lokhande, B.

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0125-9

PPy-Cr2O3 hybrid flexible electrodes (HFEs) have been synthesized by successive ionic layer adsorption and reaction (SILAR) method using flexible aluminum (Al) strips (derived from cold drink cans) as substrates. For the synthesis, 0.1 M pyrrole and 0.02 M K2Cr2O7 dissolved in 0.5 M aqueous H2SO4 were used as precursors while the flexible aluminum strips derived from waste cold drink cans were used as substrates. XRD pattern shows the peak at $$50.48^\circ$$ 50 . 48 ∘ indicating the existence of rhombohedral Cr2O3 in the hybrid. FTIR spectrum corroborates the formation of hybrid. SEM image exhibits porous morphology with interconnected granules. TEM image depicts the Cr2O3 granules of average size 20 nm and PPy globules of average size 50 nm. The liquid–solid contact angle was found to be $$10^\circ 30{\prime }$$ 10 ∘ 30 ′ indicating the near-superhydrophilic nature of HFE. Cyclic voltammetric (CV) analyses of HFEs have been carried out in each of 20 ml, 0.5 M solutions H2SO4, Na2SO4, and K2SO4. Changes in potential window, redox behavior and hence, the specific capacitance have been observed. The pseudocapacitance of HFE is combined effect of doping–dedoping of PPy matrix with SO4 2− anions as well as redox reaction shown by Cr2O3. HFE shows maximum specific capacitance 4246 Fg−1 in K2SO4 as measured from CV. HFE shows appreciable stability with 58.20% retention in capacitance even after 1000 cycles.

Calva-Yáñez, J.; Solís de la Fuente, M.; Ramírez-Vargas, M.; Rincón, M.

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0126-8

Electron lifetime and photoelectrochemical performance of carbon-doped TiO2 electrodes are presented. Thin films of random disposed ribbon-like structures of C-doped TiO2 were applied onto FTO substrates using spray and dip-coating techniques. The fabricated electrodes show photocurrent enhancement 20 times greater than compact TiO2 electrode, and electron lifetimes 2 orders of magnitude lower than compact TiO2 films. Enhancement in photocurrent suggests a beneficial role of C-doping which compensates the transport properties expected to deteriorate in disordered and thicker architectures. Due to its large surface area, C-doped TiO2 electrodes can be used as matrix for the deposition of QD sensitizers for photovoltaic applications or as photoanode for photocatalytic applications. Still optimization on film thickness and passivation strategies must be implemented to increase the carrier lifetime.

Wagh, Rahul; Kulkarni, Anil; Baviskar, Prashant; Pathan, Habib; Patil, Rajendra

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0119-7

This work reports a chemical solution sensitization of HgS nanocrystals on mesoporous TiO2 films for different deposition times. The adsorption of the precursor ions and the surface growth of the crystal were found to be affected during the temporal deposition of the HgS over spin-coated TiO2 films. The synthesized electrodes were characterized by structural, morphological, wettability, optical, photovoltaic, and electrochemical performances. The results designate the qualitative confirmation of the TiO2/HgS heterojunction formation, and the combination is explored for the photovoltaic application, which is first of its kind.

Wagh, Rahul; Kulkarni, Anil; Baviskar, Prashant; Pathan, Habib; Patil, Rajendra

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0124-x

In the original version of this article, the name of the following author name was not correct.

Vijayaraghavan, S.; Ashok, Aditya; Gopakumar, Gopika; Menon, Harigovind; Nair, Shantikumar; Shanmugam, Mariyappan

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0120-1

Cadmium telluride (CdTe) thin films of different thicknesses deposited onto titanium dioxide (TiO2) nanoparticle layer by spray pyrolysis deposition (SPD) are demonstrated as major photo-active semiconductor in photo-electrochemical solar cell configuration using iodide/triiodide (I−/I3 −) redox couple as a hole transport layer. The CdTe–TiO2 heterogeneous films were characterized by X-ray photoelectron spectroscopy which identified doublet split of Cd 3d and Ti 2p which confirms CdTe and TiO2. Optical absorbance and transmittance of CdTe and TiO2 films which were examined by UV–Vis spectroscopy confirm that the optical bandgap of CdTe is 1.5 eV with a dominant photo-absorption in the spectral window of 350–800 nm, while TiO2 showed a bandgap of 3.1 eV and is optically transparent in the visible spectral window. The present work examined photo-anodes comprising 1, 3, 5, and 10 SPD cycles of CdTe coated on TiO2 nanoparticle layer. The solar cell with 5 SPD cycles of CdTe resulting in 0.4% efficiency. Results can be articulated to the CdTe deposited by 5 SPD cycles provided an optimum surface coverage in the bulk of TiO2, while the higher SPD cycles leads to agglomeration which blocks the porosity of the heterogeneous films.

Rahmaninasab, Mohammad; Raygan, Shahram; Abdizadeh, Hossein; Pourabdoli, Mahdi; Mirghaderi, Seyyed

2018 Materials for Renewable and Sustainable Energy

doi: 10.1007/s40243-018-0122-z

MgH2 + mischmetal nanostructured composite was synthesized from MgH2 plus 6 and 10 wt% of mischmetal by ball-milling at various times. XRD studies revealed that cerium hydride was produced during the milling in all samples. Sievert test results indicated that the samples containing 6 wt% of mischmetal showed a higher desorption compared with the ones containing 10 wt% of mischmetal. The high amount of cerium hydride in the samples may be the reason, while hydrogen desorption properties decreased by adding more catalyst. Furthermore, BET results showed that the addition of the catalyst to the samples resulted in agglomerate formation in shorter milling times. The agglomerate formation increased with adding more amounts of mischmetal, thus decreasing the hydrogen desorption properties of the composite. The best results were obtained from the 30 h-milled sample containing 6 wt% of catalyst. The on-set desorption temperature of this sample was 100 °C lower than that of as-received MgH2.