Effect of pH on Anodic Formation of Nanoporous Gold Films in Chloride Solutions: Optimization of Anodization for Ultrahigh Porous Structures

Nanoporous gold (NPG) structures have useful applications based on their unique physical and chemical properties; therefore, the development of NPG preparation methods is the subject of extensive research. Recently, the anodization of Au surfaces was suggested as an efficient method for preparing porous Au structures. In this work, the mechanistic aspects of the anodization of Au in Cl^–-containing solutions for the preparation of NPG layers were investigated. The effects of the experimental parameters of the anodization reaction on the porosity of the NPG layers in terms of the roughness factor (<i>R</i>_f) were examined. The anodic formation of NPG was more effective in buffered solutions than in unbuffered electrolytes. The <i>R</i>_f of the NPG layer was sensitive to the electrolyte pH; this was ascribed to the efficient formation of protecting layers of gold oxide on the newly formed NPG structures. In buffer solutions at pH 8, ultrahigh porous NPG layers with <i>R</i>_f values of 1300 were obtained within 15 min. The ultrahigh porous NPG layers were used for the electrochemical detection of glucose; a high sensitivity of 135 μA mM^–1 cm^–2 was achieved in the presence of 0.1 M Cl^–. This straightforward and time-saving preparation of NPG surfaces will provide new opportunities for applications of NPG structures

Disentangling plasmonic and catalytic effects in a practical plasmon-enhanced Lithium–Oxygen battery

Despite possessing high theoretical energy density, rechargeable Li–O2 batteries face critical drawbacks towards commercialization. In line with recent attempts to integrate solar energy exploitation in high-energy storage, here we investigate the promise of plasmonic materials with unique light-interacting properties (localized surface plasmon resonance, LSPR) and emerging application in catalysis. Au nanoparticles (NPs) at increasing contents/sizes are incorporated on conventional Ketjen Black cathodes, with preliminary half-cell measurements underlining the promise of LSPR-generated hot-carriers on the O2 electrochemistry. The illuminated battery with facile Li2O2 formation/decomposition, small Li2O2 particles, and suppressed carboxylate side-products unlocks a round-trip efficiency boost from 75.2 to 80.2% (first cycle) and a ?1.2-fold full capacity enhancement. Even more remarkably, with continuous cycling (30 cycles), a 680 mV-overpotential suppression is here reported. Comparatively, dark conditions reveal negligible Au-driven catalytic effects, whereas LSPR-induced local heat effects are ruled out upon meticulous assessment of the product selectivity in cells at increasing temperatures. These outstanding efficiencies are ensured even with larger particles (5–100 nm), as corroborated by corresponding galvanostatic profiles and finite-difference time-domain simulations, pinpointing the practicality of our cathodes towards scale-up. This contribution is the first to disentangle catalytic effects and plasmon relaxation pathways over practical carbon-based cathodes for high-energy storage.</p

sj-docx-1-jpe-10.1177_0739456X211044215 – Supplemental material for Changing Trends in Long-Term Sentiments and Neighborhood Determinants in a Shrinking City

Supplemental material, sj-docx-1-jpe-10.1177_0739456X211044215 for Changing Trends in Long-Term Sentiments and Neighborhood Determinants in a Shrinking City by Yunmi Park, Minju Kim, Jiyeon Shin and Megan E. Heim LaFrombois in Journal of Planning Education and Research</p

Single-Phase Perovskite SrIrO₃ Nanofibers as a Highly Efficient Electrocatalyst for a pH-Universal Oxygen Evolution Reaction

pH-universal electrocatalysts are desirable for high efficiency of water electrolysis. Herein, we report the facile synthesis of single-phase perovskite SrIrO3 nanofibers (NFs) and demonstrate that SrIrO3 NFs are promising electrocatalysts for the oxygen evolution reaction (OER) in a wide range of pH. Single-phase SrIrO3 NFs were synthesized by electrospinning and subsequent calcination processes, and the electrocatalytic performance of SrIrO3 NFs toward the OER was evaluated under acidic, neutral, and alkaline media. A large surface area due to the NF morphology with an average diameter of 105.5 (± 15.5) nm led to enhanced catalytic activity of SrIrO3 NFs, representing smaller overpotentials and Tafel slopes under pH-universal conditions than IrO2/Ir NFs and commercial Ir/C. SrIrO3 NFs also manifested remarkably stable activity for continuous OER operation in all three electrolytes, even though a considerable amount of Sr was leached out of them. The long-lasting high OER activity of SrIrO3 NFs could be ascribed to stable Ir cations taking B sites of the perovskite oxide structure, known as an active site for electrocatalysis. The initial perovskite crystal structure of SrIrO3 was maintained for a certain time even after significant Sr leaching. This work is the first application of SrIrO3 perovskite for pH-universal OER catalysis

Block Copolymer Enabled Synthesis and Assembly of Chiral Metal Oxide Nanoparticle

Chiral metal oxide nanostructures have received tremendous attention in nanotechnological applications owing to their intriguing chiroptical and magnetic properties. Current synthetic methods mostly rely on the use of amino acids or peptides as chiral inducers. Here, we report a general approach to fabricate chiral metal oxide nanostructures with tunable magneto-chiral effects, using block copolymer (BCP) inverse micelle and R/S-mandelic acid (MA). Diverse chiral metal oxide nanostructures are prepared by the selective incorporation of precursors within micellar cores followed by the oxidation process, exhibiting intense chiroptical properties with a g-factor up to 7.0 × 10–3 in the visible–NIR range for the Cr2O3 nanoparticle multilayer. The BCP inverse micelle is found to inhibit the racemization of MA, allowing MA to act as a chiral dopant that imparts chirality to nanostructures via hierarchical chirality transfer. Notably, for paramagnetic nanostructures, magneto-chiroptical modulation is realized by regulating the direction of the external magnetic field. This BCP-driven approach can be extended to the mass production of chiral nanostructures with tunable architectures and optical activities, which may provide insights into the development of chiroptical functional materials

Synthesis of Bicyclic <i>N</i>‑Heterocycles via Photoredox Cycloaddition of Imino-Alkynes and Imino-Alkenes

Cycloaddition reactions offer great advantages regarding atom and step economy for the construction of various carbocycles and heterocycles. While the recent development based on sensitized visible light photocatalysis allowed the synthesis of azetidines via imine-alkene [2 + 2] cycloaddition, imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis has not been reported. In this regard, we report the synthesis of pyrrolizidinones based on intramolecular imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis. This redox-neutral reaction involves formal imine-alkyne metathesis followed by redox-mediated annulation with concomitant rearrangement. In contrast, the use of imino-alkenes provides dihyro-1,4-oxazines via an alternative [4 + 2] cycloaddition pathway. The proposed reaction mechanisms were supported by control experiments and DFT calculations

Synthesis of Bicyclic <i>N</i>‑Heterocycles via Photoredox Cycloaddition of Imino-Alkynes and Imino-Alkenes

Cycloaddition reactions offer great advantages regarding atom and step economy for the construction of various carbocycles and heterocycles. While the recent development based on sensitized visible light photocatalysis allowed the synthesis of azetidines via imine-alkene [2 + 2] cycloaddition, imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis has not been reported. In this regard, we report the synthesis of pyrrolizidinones based on intramolecular imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis. This redox-neutral reaction involves formal imine-alkyne metathesis followed by redox-mediated annulation with concomitant rearrangement. In contrast, the use of imino-alkenes provides dihyro-1,4-oxazines via an alternative [4 + 2] cycloaddition pathway. The proposed reaction mechanisms were supported by control experiments and DFT calculations

Segmentation and Analysis Method for 3D Cell Structures Enhanced with Open-Source AI Tools in Holotomography Images

Poster presented as part of the Crick BioImage Analysis Symposium 2024.Permission has been given by authors to upload to Crick Figshare. Copyright remains with the original authors.</p

Synthesis of Bicyclic <i>N</i>‑Heterocycles via Photoredox Cycloaddition of Imino-Alkynes and Imino-Alkenes

Cycloaddition reactions offer great advantages regarding atom and step economy for the construction of various carbocycles and heterocycles. While the recent development based on sensitized visible light photocatalysis allowed the synthesis of azetidines via imine-alkene [2 + 2] cycloaddition, imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis has not been reported. In this regard, we report the synthesis of pyrrolizidinones based on intramolecular imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis. This redox-neutral reaction involves formal imine-alkyne metathesis followed by redox-mediated annulation with concomitant rearrangement. In contrast, the use of imino-alkenes provides dihyro-1,4-oxazines via an alternative [4 + 2] cycloaddition pathway. The proposed reaction mechanisms were supported by control experiments and DFT calculations

Synthesis of Bicyclic <i>N</i>‑Heterocycles via Photoredox Cycloaddition of Imino-Alkynes and Imino-Alkenes

Cycloaddition reactions offer great advantages regarding atom and step economy for the construction of various carbocycles and heterocycles. While the recent development based on sensitized visible light photocatalysis allowed the synthesis of azetidines via imine-alkene [2 + 2] cycloaddition, imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis has not been reported. In this regard, we report the synthesis of pyrrolizidinones based on intramolecular imine-alkyne [2 + 2] cycloaddition under visible light photocatalysis. This redox-neutral reaction involves formal imine-alkyne metathesis followed by redox-mediated annulation with concomitant rearrangement. In contrast, the use of imino-alkenes provides dihyro-1,4-oxazines via an alternative [4 + 2] cycloaddition pathway. The proposed reaction mechanisms were supported by control experiments and DFT calculations