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To probe the phase structure–reactivity relationship of A2B2O7 catalysts for the oxidative coupling of methane (OCM), three model La2B2O7 compounds with Ti4+, Zr4+, or Ce4+ at the B-site have been purposely designed. By decreasing the r A/r B ratios in the order of La2Ti2O7 > La2Zr2O7 > La2Ce2O7, typical monoclinic layered perovskite, cubic ordered pyrochlore, and disordered defective cubic fluorite phase are formed, respectively. The reaction performance of the catalysts based on CH4 conversion and C2 product yield follow the order of La2Ce2O7 > La2Zr2O7 > La2Ti2O7. It has been discovered that superoxide O2 – is the active oxygen species detected on all the catalysts and is responsible for the OCM reaction, whose amount follows also the sequence of La2Ce2O7 > La2Zr2O7 > La2Ti2O7. Moreover, the surface alkalinity related to the superoxide anions observes the same order. This testifies that the amount of surface superoxide O2 – determines the OCM reaction performance over the La2B2O7 compounds. On the basis of the characterization results, the formation of active O2 – species could follow two pathways. For La2Zr2O7 and La2Ce2O7 possessing intrinsic 8a oxygen vacancies, O2 – anions are formed by activating the oxygen species entering into the vacancies in the bulk and then migrating to the catalyst surface. For La2Ti2O7 possessing no oxygen vacancies, they are formed directly by transforming the O2 molecules adsorbed on its surface. Usually, the former pathway generates more abundant O2 – species than the latter one. La2Ce2O7 displays not only promising reaction performance in the low-temperature region, but also potent sulfur and lead poisoning resistance, thus having the potential for application after further optimization.

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Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfO/ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

This work provides a consistent picture of the structural, optical and electronic properties of Fe doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations ranging from 5×10 17 cm −3 to 2×10 20 cm −3 is systematically investigated by means of electron paramagnetic resonance and various optical techniques. Fe 3+ is shown to be a stable charge state at concentrations from 1×10 18 cm −3 . The fine structure of its mid-gap states is successfully established including an effective-mass-like state consisting of a hole bound to Fe 2+ with a binding energy of 50±10 meV. A major excitation mechanism of the Fe 3+ ( 4 T 1 -6 A 1 ) luminescence is identified to be the capture of free holes by Fe 2+ centers. The holes are generated in a two step process via the intrinsic defects involved in the yellow luminescence. The Fe 3+/2+ charge transfer level is found 2.863±0.005 eV above the valence band, suggesting that the internal reference rule does not hold for the prediction of band off-sets of heterojunctions between GaN and other III-V materials. The Fe 2+ ( 5 E-5 T 2 ) transition is observed around 390 meV at any studied Fe concentration by means of Fourier transform infra red spectroscopy. Charge transfer processes and the effective-mass-like state involving both Fe 2+ states are observed. At Fe concentrations from 1×10 19 cm −3 , additional lines occur in EPR and PL spectra which are attributed to defect complexes involving Fe 3+ . With increasing Fe concentration, the Fermi level is shown to move from near the conduction band to the Fe 3+/2+ charge transfer level, where it stays pinned for concentrations from 1×10 19 cm −3 . Contrary to cubic II-VI and III-V materials, both electronic states are effected by only a weak Jahn-Teller interaction.

Nanoparticle-based systems explore not only the delivery efficacy of drugs or contrast agents, but also additional capabilities like reducing the systemic toxicity, especially during cancer chemotherapy. Since some of the noble metal nanoparticles exhibit the catalysis properties which can scavenge the reactive oxygen species (ROS), they can be used as a promising drug delivery platform for reducing the oxidative stress damage in normal tissues caused by some chemotherapy drugs. Herein, in this study, we construct porous Au@Pt nanoparticles and further explore the properties of porous Au@Pt nanoparticles in relieving the oxidative stress damage as well as in tumor growth inhibition by chemo-photothermal co-therapy. The tunable surface pore structure of Au@Pt nanoparticle provides space for Doxorubicin (DOX) loading. cRGD peptide modification enable the DOX-loaded Au@Pt nanoparticles to improve drug delivery properties. The constructed nanocarrier (DOX/Au@Pt-cRGD) shows controlled drug release behavior. Meanwhile, the absorbance peak of the Au@Pt structure in the near-infrared (NIR) portion provides the capacity for in vivo photoacoustic imaging and the high photoconversion efficiency, which make Au@Pt nanoparticle a suitable carrier for photothermal therapy (PTT). Combined with chemotherapy, the nanosystem DOX/Au@Pt-cRGD shows enhanced anticancer therapeutic effects. More importantly, ROS-scavenging activity of Au@Pt alleviates the DOX-induced oxidative stress damage, especially the cardiomyopathy during chemotherapy. Herein, this nanosystem DOX/Au@Pt-cRGD could be explored as reactive oxygen scavenger and drug delivery system for side effects relieving chemo-photothermal combinational therapy.

The structure and stability of endohedral X@C60F n (X = N, H; n = 1, 2) and (H@C60)2 are computed at the B3LYP level of density functional theory. The most stable N@C60F has one endo N−C bond, while N@C60F2 favors nitrogen atom at the cage center. Both H@C60F and H@C60F2 favor isomers with one endo C−H bond. The most stable dimer structure, (H@C60)2, has one intercage C−C bond and two endo C−H bonds, and is stable below 650 K, but dissociates above 650 K.