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With the resistive random access memory (ReRAM) devices based on the Al/BaTiO3 (BTO)/ITO structure fabricated at hand, by cross-analyzing the resistive memory characteristics in terms of various barium titanate (BTO) film thicknesses, it is found that the device with 60 nm thick BTO can be switched more than 425 times, while the corresponding SET/RESET voltage, the on-off ratio, and the retention time are −0.69 V/0.475 V, 102, and more than 104 seconds, respectively. Furthermore, the aforementioned ReRAM with a low switching voltage and low power consumption is further integrated with a waveguide resonator in the form of a dual microdisk aligned in a parallel fashion. As the separation gap between the two microdisks is fixed at 15 μm, the ReRAM-mediated dual disk resonator would render a 180° phase reversal between the spectral outputs of the through-port and drop-port. If the gap is shortened to 10 and 5 μm, the expected phase reversal could also be retrieved due to the selective combinations of different memory states associated with each of the two ReRAM microdisks as witnessed by a series of characterization measurements. [ABSTRACT FROM AUTHOR]

This work investigates experimentally and numerically the chemical kinetics of OH species generated in kHz helium atmospheric-pressure dielectric barrier discharges with different H2O concentrations. The OH densities of cases are determined from measurements of the ultraviolet absorption spectroscopy (UVAS) system with transition parameters evaluated by LIFBASE. The 1D plasma fluid model (PFM) with compiled chemistry covering chemical kinetics of helium, H2O, and interaction reactions of reactive species including the formation of charged cluster ions is employed to capture the discharge dynamics for analyzing mechanisms of OH species properly. The simulated current densities of cases with 0.8% and 2.0% H2O concentrations increase from 29 to 51 A mâˆ'2, agreeing with experimental measurements. The simulated OH density increases from 1.7 Ă— 1019 mâˆ'3 to 2.4 Ă— 1019 mâˆ'3 as the H2O concentration increases from 0.4% to 2.0%, agreeing with OH densities interpreted from the UVAS system for cases with various H2O concentrations. In general, the 1D PFM developed captures the discharge behavior and predicts the OH densities of cases with different H2O concentrations. The simulated results reveal that the electron and H2O+ are essential species for OH production through dissociative reactions (e + H2O â†' e + OH + H) and (H2O+ + H2O â†' H+(H2O) + OH) contributing to 61% and 23% of OH production, respectively. It is observed that the OH self-recombination reaction (OH + OH + He â†' H2O2 + He) contributes to 32% of OH consumption as the dominant reaction. Moreover, the stepwise recombination reactions (OH + H2O2 â†' H2O + HO2 and OH + HO2 â†' O2 + H2O) initiated by OH species contribute to the overall 27% of OH consumption as another dominant mechanism. The Penning ionization reactions involving water molecules are the dominant reactions for electron production in the present discharge with H2O up to 0.8%, then the electron-impact ionization becomes the dominant reaction for electron production in cases with higher H2O concentrations. As the essential species contributing to the OH consumption, H species is produced majorly from the dissociation reaction (e + H2O â†' e + OH + H). As one of the dominant OH production reactions, the dissociative attachment (e + H2O â†' Hâˆ' + OH) is the dominant electron consumption reaction, resulting in the reactive Hâˆ' species as the source of negative cluster ions. The high average reaction rates of dissociative attachment reactions consume most of the electrons after the breakdown, which leads to the variation of discharge current density. The saturation of OH species, which is observed experimentally and numerically, is attributed to the transition of electron chemical kinetics and the recombination reactions of OH species. [ABSTRACT FROM AUTHOR]

Plasmonic photocatalysis, combing noble metal nanoparticles (NMNPs) with semiconductors, has been widely studied and proven to perform better than pure semiconductors. The plasmonic effects are mainly based on the localized surface plasmon resonance (LSPR) of NMNPs. The LSPR wavelength depends on several parameters, such as size, shape, the surrounding media, and the interdistance of the NMNPs. In this study, graphene-modified plate-like BiVO4 composites, combined with silver nanoplates (AgNPts), were successfully prepared and used as a photocatalyst for CO2 photoconversion. Triangular silver nanoplates (TAgNPts), icosahedral silver nanoparticles (I-AgNPs), and decahedra silver nanoparticles (D-AgNPs) were synthesized using photochemical methods and introduced to the nanocomposites to compare the shape-dependent plasmonic effect. Among them, T-AgNPts/graphene/BiVO4 exhibited the highest photoreduction efficiency of CO2 to CH4, at 18.1 μmolg−1h−1, which is 5.03 times higher than that of pure BiVO4 under the irradiation of a Hg lamp. A possible CO2 photoreduction mechanism was proposed to explain the synergetic effect of each component in TAgNPts/graphene/BiVO4. This high efficiency reveals the importance of considering the compositions of photocatalysts for converting CO2 to solar fuels. [ABSTRACT FROM AUTHOR]