CO2 Bubble-Assisted Pt Exposure in PtFeNi Porous Film for High-Performance Zinc-Air Battery.

Fine-tuning the exposed active sites of platinum group metal (PGM)-based materials is an efficient way to improve their electrocatalytic performance toward large-scale applications in renewable energy devices such as Zn-air batteries (ZABs). However, traditional synthetic methods trade off durability for the high activity of PGM-based catalysts. Herein, a novel dynamic CO2-bubble template (DCBT) approach was established to electrochemically fine-tuning the exposed Pt active sites in PtFeNi (PFN) porous films (PFs). Particularly, CO2 bubbles were intentionally generated as gas-phase templates by methanol electrooxidation. The generation, adsorption, residing, and desorption of CO2 bubbles on the surface of PFN alloys were explored and controlled by adjusting the frequency of applied triangular-wave voltage. Thereby, the surface morphology and Pt exposure of PFN PFs were controllably regulated by tuning the surface coverage of CO2 bubbles. Consequently, the Pt1.1%Fe8.8%Ni PF with homogeneous nanoporous structure and sufficiently exposed Pt active sites was obtained, showing preeminent activities with a half-wave potential (E1/2) of 0.87 V and onset overpotential (ηonset) of 288 mV at 10 mA cm-2 for oxygen reduction and evolution reactions (ORR and OER), respectively, at an ultralow Pt loading of 0.01 mg cm-2. When tested in ZABs, a high power density of 175.0 mW cm-2 and a narrow voltage gap of 0.64 V were achieved for the long cycling tests over 500 h (750 cycles), indicating that the proposed approach can efficiently improve the activity of PGM catalysts by fine-tuning the microstructure without compromising the durability.

In situ TEM Characterization of Microstructure Evolution and Mechanical Behavior of the 3D-Printed Inconel 718 Exposed to High Temperature.

This in situ transmission electron microscopy work presents a nanoscale characterization of the microstructural evolution in 3D-printed Inconel 718 (IN718) while exposed to elevated temperature and an associated change in the mechanical property under tensile loading. Here, we utilized a specially designed specimen shape that enables tensile testing of nano-sized thin films without off-plane deformations. Additionally, it allows a seamless transition from the in situ heating to tensile experiment using the same specimen, which enables a direct correlation of the microstructure and the mechanical property of the sample. The method was successfully used to observe the residual stress relaxation and the formation of incoherent γ' precipitates when temperature was increased to 700°C. The subsequent in situ tensile test revealed that the exposure of the as-printed IN718 to a high temperature without full heat treatment (solutionizing and double aging) leads to loss of ductility.

Correction: Antioxidant properties of ALD grown nanoceria films with tunable valency.

Correction for 'Antioxidant properties of ALD grown nanoceria films with tunable valency' by Ankur Gupta et al., Biomater. Sci., 2019, DOI: 10.1039/c9bm00397e.

Antioxidant properties of ALD grown nanoceria films with tunable valency.

Herein, we provide the first account of a method to control cerium oxide's mixed valence states (as Ce3+ to Ce4+ ratio) in ultra-thin films formed via atomic layer deposition (ALD). It is determined that modulation of Ce3+/Ce4+ ratio occurs with respect to film thickness and is analogous to the change in surface chemistry observed for cerium oxide nanoparticles with varying particle diameter. The influence of film thickness on enzyme-mimetic radical scavenging is also characterized. Higher film thicknesses show 9-fold increase in catalytic activity. In vitro biocompatibility (apoptosis < 4%) and electrochemical biosensing (lowest concentration: 18 ppt) studies were performed to demonstrate the potential of ALD-grown nanoceria films for biomedical applications.

Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study.

In this study, the thermal stability of a contact structure featuring hole-selective tungsten oxide (WOx) and aluminum deposited onto p-type crystalline silicon (c-Si/WOx/Al) was investigated using a combination of transmission line measurements (TLM) and in situ transmission electron microscopy (TEM) studies. The TEM images provide insight into why the charge carrier transport and recombination characteristics change as a function of temperature, particularly as the samples are annealed at temperatures above 500 °C. In the as-deposited state, a ≈ 2 nm silicon oxide (SiOx) interlayer forms at the c-Si/WOx interface and a ≈ 2-3 nm aluminum oxide (AlOx) interlayer at the WOx/Al interface. When annealing above 500 °C, Al diffusion begins, and above 600 °C complete intermixing of the SiOx, WOx, AlOx and Al layers occurs. This results in a large drop in the contact resistivity, but is the likely reason surface recombination increases at these high temperatures, since a c-Si/Al contact is basically being formed. This work provides some fundamental insight that can help in the development of WOx films as hole-selective rear contacts for p-type solar cells. Furthermore, this study demonstrates that in situ TEM can provide valuable information about thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells.

Periodically Ordered Nanoporous Perovskite Photoelectrode for Efficient Photoelectrochemical Water Splitting.

Nonmetallic materials with localized surface plasmon resonance (LSPR) have a great potential for solar energy harvesting applications. Exploring nonmetallic plasmonic materials is desirable yet challenging. Herein, an efficient nonmetallic plasmonic perovskite photoelectrode, namely, SrTiO3, with a periodically ordered nanoporous structure showing an intense LSPR in the visible light region is reported. The crystalline-core@amorphous-shell structure of the SrTiO3 photoelectrode enables a strong LSPR due to the high charge carrier density induced by oxygen vacancies in the amorphous shell. The reversible tunability in LSPR of the SrTiO3 photoelectrode was observed by oxidation/reduction treatment and incident angle adjusting. Such a nonmetallic plasmonic SrTiO3 photoelectrode displays a dramatic plasmon-enhanced photoelectrochemical water splitting performance with a photocurrent density of 170.0 µA cm-2 under visible light illumination and a maximum incident photon-to-current-conversion efficiency of 4.0% in the visible light region, which are comparable to the state-of-the-art plasmonic noble metal sensitized photoelectrodes.

Biochemical manifestations of anti-tuberculosis drugs induced hepatotoxicity and the effect of silymarin.

In the present study, the biochemical manifestations of liver toxicity caused by co-administration of anti-TB drugs, rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA), in a sub-chronic mode (12 weeks), were investigated. Significant alterations were revealed in (a) increased levels of alanine aminotrasferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) and a high bilirubin content in serum; (b) elevated lipid peroxidation (LPO), intracellular calcium [Ca(2+)](i) and CYP4502EI activity in liver; and (c) decreased glutathione (GSH) content, glutathione peroxidase (GPx) and catalase activities in liver. Silymarin reversed these abnormal alterations. The biochemical changes were supported by histological observations.