Influence of Oxidative Etching of Au Nanostructures by KMnO4 on its Surface Morphology, Electro-kinetic Properties and Improved Catalytic Activity

Etching-Based Chiroplasmonic Sensing with Helicoid Au Nanocrystals for Anti-Interference Biochemical Detection

Plasmonic nanomaterials with intrinsic chiral morphology represent a profound and intriguing topic in sensing applications due to their ultrasensitive chiral structure-dependent chiroptical activity. Here, an H2O2-assisted etching strategy is reported, enabling the tunable chiroptical activity of chiral helicoid Au nanocrystals by varying size and morphology. This approach forms the foundation of a chiroplasmonic sensing method leveraging the chiroptical signal response induced by morphological changes. Notably, the method exhibits excellent anti-interference performance, enabling reliable detection in complex and colored sample environments. Moreover, the strategy is extended for glucose detection through glucose oxidase-catalyzed H2O2 production, with quantitative detection in real colored samples confirming its reliability. The chiroplasmonic sensing based on helicoid Au nanocrystal etching exhibits remarkable detection performance in complex environments, offering the potential for practical applications in biochemical analysis and diagnostics.

Chemically Roughened, Sputtered Au Films with Trace-Loaded Manganese Oxide for both On-Chip and Off-Chip High Frequency Supercapacitors

High frequency supercapacitors (HFSCs) are promising in alternating current line filtering and adaptable storage of high-frequency pulse electrical energy. Herein, we report a facile yet integrated-circuit-compatible fabrication of HFSC electrodes by combining chemical roughening of the sputtered metal (Au) films and in situ trace loading of a pseudocapacitive material (MnO x ). The developed electrode fabrication route is versatile for different substrates, and is described with the application paradigms of both on-chip (with Si/SiO2 substrate) and off-chip (without Si/SiO2 substrate, with Ti substrate as an example in this study) HFSCs. With Au/MnO x films on Si/SiO2 substrates as the working electrodes, the derived on-chip HFSC displayed satisfactory performance in high frequency applications (i.e., an areal capacitance of 131.7 µF cm-2, a phase angle of -78°, and a RC time constant of 0.27 ms, at 120 Hz).

Polyhedral 30-Faceted BiVO4 Microcrystals Predominantly Enclosed by High-Index Planes Promoting Photocatalytic Water-Splitting Activity

Unprecedented 30-faceted BiVO₄ polyhedra predominantly surrounded by {132}, {321}, and {121} high-index facets are fabricated through the engineering of high-index surfaces by a trace amount of Au nanoparticles. The growth of high-index facets results in a 3-5 fold enhancement of O₂ evolution from photocatalytic water splitting by the BiVO₄ polyhedron, relative to its low-index counterparts. Theory calculations reveal that water dissociation is more energetically favorable on the high-index surfaces than on the low-index (010), (110), and (101) surfaces, which is accompanied by a notable reduction in the overpotential (0.77-1.14 V) for the oxygen evolution reaction. The apparent quantum efficiency of O₂ generation without an external electron supply reaches 18.3% under 430 nm light irradiation, which is an order of magnitude higher than that of the catalysts reported hitherto.