Structure,antioxidative potency and potential scavenging of OH and OOH of phenylethyl-3,4-dihydroxyhydrocinnamate in protic and aprotic media: DFT study

DFT methods including B3LYP, B3PW91 and M05–2 x associated to 6–31 + G(d,p) were used for the structural and antioxidant potency studies of phenylethyl-3,4-dihydroxy-hydrocinnamate (PDH). Solvents were employed according to their protric and aprotic character. So, calculated structures agree with the experimental data. O₄H₄ is propitious to scavenge radicals whatever the medium except in water where O₃H₃ and O₄H₄ are competitive. The explicit solvents of dichloromethane (DCM) and water present a disparity of OH bond dissociation enthalpy and free energy (BDE and BDFE). These parameters are low in continuum except in water. The ionization potentials (IP) and potential affinities (PA) are low in solvents. BDE, IP and PA are each, approximatively constant in mixed solvent treatment in water using n-H₂O (n = 3,5,8). Elsewhere, H-atom transfer (HAT) mechanism is favoured in vacuum and DCM, whereas sequential proton loss electron transfer (SPLET) is likely in protic solvents. A discord between HAT and SPLET in benzene is observed. The PDH compound is more antioxidant and resistant to oxidation than caffeic acid phenethyl ester (CAPE). The potential of scavenging of OH and OOH whatever the reaction channel shows that they decay rapidly in any media through HAT. PDH is easily deprotonated in the protic solvents and the resulting product is the most antioxidant and the least resistant to oxidation.     

The effect of external electric field on the performance of perovskite solar cells

Planar heterojunction perovskite solar cells were fabricated through a low temperature approach. We find that the device performance significantly depends on the external bias before and during measurements. By appropriate optimization of the bias conditions, we could achieve an 8-fold increase in the power conversion efficiency. The significant improvement in device performance might be caused by the ion motion in the perovskite under the external electric field.     

A Transmetalation Synthetic Strategy to Engineer Atomically Dispersed MnN2O2 Electrocatalytic Centers Driving High-Performance Li?S Battery

Sluggish sulfur redox reaction (SROR) kinetics accompanying lithium polysulfides (LiPSs) shuttle effect becomes a stumbling block for commercial application of Li S battery. High-efficient single atom catalysts (SACs) are desired to improve the SROR conversion capability; however, the sparse active sites as well as partial sites encapsulated in bulk-phase are fatal to the catalytic performance. Herein, high loading (5.02 wt.%) atomically dispersed manganese sites (MnSA) on hollow nitrogen-doped carbonaceous support (HNC) are realized for the MnSA@HNC SAC by a facile transmetalation synthetic strategy. The thin-walled hollow structure (≈12 nm) anchoring the unique trans-MnN₂O₂ sites of MnSA@HNC provides a shuttle buffer zone and catalytic conversion site for LiPSs. Both electrochemical measurement and theoretical calculation indicate that the MnSA@HNC with abundant trans-MnN₂O₂ sites have extremely high bidirectional SROR catalytic activity. The assembled Li S battery based on the MnSA@HNC modified separator can deliver a large specific capacity of 1422 mAh g⁻¹ at 0.1 C and stable cycling over 1400 cycles with an ultralow decay rate of 0.033% per cycle at 1 C. More impressively, a flexible pouch cell on account of the MnSA@HNC modified separator may release a high initial specific capacity of 1192 mAh g⁻¹ at 0.1 C and uninterruptedly work after the bending-unbending processes.     

In-situ study on hydrogen bubble evolution in the liquid Al/solid Ni interconnection by synchrotron radiation X-ray radiography

Synchrotron X-ray radiography was used to carry out an in-situ observation of the hydrogen bubble evolution in the liquid Al/solid Ni interconnection. The individual bubble mainly grows in a stochastic way during heating. The size distribution for groups of bubbles follows a Gaussian distribution in the early stage and Lifshitz-Slyozov-Wagner (LSW) diffusion controlled distribution in the final stage. The intermetallic compounds (IMCs) first form during solidification, following by the hydrogen bubbles. The bubbles between two adjacent Al₃Ni grains grow unidirectionally along the liquid channel, with the bottom being impeded by the Al₃Ni phase and the radius of the growth front being smaller. For the bubbles at triple junctions, they grow along the liquid channel and the crack with morphology transition.     

WO3 cocatalyst improves hydrogen evolution capacity of ZnCdS under visible light irradiation

Semiconductor photocatalysts can convert solar energy into clean pollution-free hydrogen energy and thus are a novel technology to alleviate the energy crisis. To acquire catalysts with higher photocatalytic hydrogen production efficiency, we synthesized ZnCdS catalysts from a hydrothermal method and the WO₃ cocatalyst through temperature-programmed reduction. The surface morphology and optical properties of the catalysts were characterized via X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis spectroscopy, which proved the successful synthesis of the WO₃/ZnCdS compound catalysts. The effects of WO₃ dosage on the photocatalytic activity of ZnCdS were studied, and in particular, the hydrogen production activity of the 35 wt% WO₃/ZnCdS was the highest to 98.68 μmol/mg, about 9.6 times that of pure ZnCdS (10.28 μmol/mg). After 5 cycles, it yet had high repeatability and preserved high hydrogen production activity after 100 h of photocatalytic tests. The underlying mechanism was explored via photoluminescence and photocurrent assays. It was found the 35 wt% WO₃/ZnCdS generated higher photocurrent than pure ZnCdS, indicating WO₃ could facilitate electron transfer to involve more electrons in hydrolysis reactions, thereby increasing the photoelectron use efficiency and photocatalytic hydrogen production activity.     

Graphite nanopowder functionalized 3-D acrylamide polymeric anode for enhanced performance of microbial fuel cell

3-D highly conductive polyvinyl formaldehyde sponges functionalized with acrylamide are fabricated using polyvinyl alcohol with varying concentrations of graphite nanopowder. The properties of the fabricated anodes are analyzed and its application in microbial fuel cells is evaluated. A comparative study with Graphite felt is also performed to evaluate its commercial viability. The presence of Hydroxyl and Amine functional groups enhanced the hydrophilic and biocompatible nature of the synthesized anodes. The phylogenetic analysis substantiated the biocompatible nature and mercury porosimetry showed macroporous nature of the fabricated anode. The highest power density of ~8 W/m² is recorded for C10 establishing solid biofilm formation. A ~94% COD removal revealed the versatility of the anode for MFC based wastewater treatment. The MFC performance was twice than that of control and was also highest among the most reported modified 3-D anodes. The durability study displayed the commercial opportunity of the anode for real-time MFC operation.     

Planar organic spin valves using nanostructured Ni80Fe20 magnetic contacts

Planar organic spin valves were fabricated by evaporating organic semiconductor PTCDI-C₁₃ onto pairs of patterned Ni₈₀Fe₂₀ magnetic nanowires separated by 120 nm. Control over the relative alignment of magnetisation in the nanowires was achieved by including a domain wall ‘nucleation pad’ at the end of one of the wires to ensure a large separation in magnetic switching fields. Switching behaviour was investigated by optical and X-ray magnetic imaging. Room temperature organic magnetoresistance of −0.35% was observed, which is large compared to that achieved in vertical spin valves with similar materials. We attribute the enhanced performance of the planar geometry to the deposition of the semiconductor on top of the metal, which improves the quality of metal–semiconductor interfaces compared to the metal-on-semiconductor interfaces in vertical spin valves.