Interfacial Engineering of Nanoporous Architectures in Ga2O3 Film toward Self-Aligned Tubular Nanostructure with an Enhanced Photocatalytic Activity on Water Splitting

Suppressed charge recombination via defect engineering of confined semiconducting quantum dots for photoelectrocatalysis

Confined semiconducting CuSe quantum dots with abundant Se vacancies are synthesized by pulsed laser deposition with in situ vacuum annealing. With the presence of Se vacancies, the photogenerated charge recombination is suppressed by the self-introduced in-gap trapping states, thus enhancing the photoelectrocatalytic activity under solar illumination.

Fabrication and Characterization of Tantalum-Iron Composites for Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution represents a transformative avenue in addressing the challenges of fossil fuels, heralding a renewable and pristine alternative to conventional fossil fuel-driven energy paradigms. Yet, a formidable challenge is crafting a high-efficacy, stable photocatalyst that optimizes solar energy transduction and charge partitioning even under adversarial conditions. Within the scope of this investigation, tantalum-iron heterojunction composites characterized by intricate, discoidal nanostructured materials were meticulously synthesized using a solvothermal-augmented calcination protocol. The X-ray diffraction, coupled with Rietveld refinements delineated the nuanced alterations in phase constitution and structural intricacies engendered by disparate calcination thermal regimes. An exhaustive study encompassing nano-morphology, electronic band attributes, bandgap dynamics, and a rigorous appraisal of their photocatalytic prowess has been executed for the composite array. Intriguingly, the specimen denoted as 1000-1, a heterojunction composite of TaO2/Ta2O5/FeTaO4, manifested an exemplary photocatalytic hydrogen evolution capacity, registering at 51.24 µmol/g, which eclipses its counterpart, 1100-1 (Ta2O5/FeTaO4), by an impressive margin. Such revelations amplify the prospective utility of these tantalum iron matrices, endorsing their candidacy as potent agents for sustainable hydrogen production via photocatalysis.

Formation of porous Ga oxide with high-aspect-ratio nanoholes by anodizing single Ga crystal

I developed a simple crystal growth process to obtain a single Ga crystal. The crystal orientation of a Ga plate could be controlled by a crystal growth process using a seed Ga crystal. By anodizing a [100]-direction highly oriented Ga plate, I realized the formation of a highly ordered array of high-aspect-ratio straight nanoholes. It was observed that the nanohole growth direction depends on the crystal orientation of a Ga plate. To date, this dependence has yet to be observed in materials other than porous Ga oxide obtained by an anodization process. The present fabrication process is expected to be applied to the fabrication of various functional devices requiring a porous Ga oxide with high-aspect-ratio straight nanoholes, such as hydrogen formation devices and functional filters.

Electrochemical Oxidation to Fabricate Micro-Nano-Scale Surface Wrinkling of Liquid Metals

Constructing wrinkled structures on the surface of materials to obtain new functions has broad application prospects. Here a generalized method is reported to fabricate multi-scale and diverse-dimensional oxide wrinkles on liquid metal surfaces by an electrochemical anodization method. The oxide film on the surface of the liquid metal is successfully thickened to hundreds of nanometers by electrochemical anodization, and then the micro-wrinkles with height differences of several hundred nanometers are obtained by the growth stress. It is succeeded in altering the distribution of growth stress by changing the substrate geometry to induce different wrinkle morphologies, such as one-dimensional striped wrinkles and two-dimensional labyrinth wrinkles. Further, radial wrinkles are obtained under the hoop stress induced by the difference in surface tensions. These hierarchical wrinkles of different scales can exist on the liquid metal surface simultaneously. Surface wrinkles of liquid metal may have potential applications in the future for flexible electronics, sensors, displays, and so on.

Field-Assisted Formation of NH4CoF3 Mesocrystals toward Hierarchical Co3O4 Cuboids as Anode Materials for Lithium-Ion Batteries

Porous NH₄CoF₃ mesocrystalline cuboids with highly exposed {100} facets are grown by in situ reaction of products produced by high field anodization of cobalt metal foil, via a nonclassical crystallization process involving oriented particle aggregation. 3D nano-micro hierarchical Co₃O₄ cuboids are obtained by thermal annealing of NH₄CoF₃ mesocrystals. The microstructure and morphology of products are characterized by electron microscopy and X-ray diffraction. The combination of small nanoparticle subunits, micrometer-sized overall particles, and porous structure provides the obtained hierarchical Co₃O₄ cuboids with large electrolyte-electrode contact areas, channels for large lithium ion flux, pore accessibility, and structural stability, leading to excellent rate and cyclic performance as lithium-ion battery (LIB) anodes.

Comparative Study of Pore Characterizations of Anodized Al–0.5 wt.% Cu Thin Films in Oxalic and Phosphoric Acids

Porous anodic alumina (PAA) thin films, having interconnected pores, were fabricated from Cu-doped aluminum films deposited on [Formula: see text]-type silicon wafers by anodization. The anodization was done at four different anodizing voltages (60[Formula: see text]V, 70[Formula: see text]V, 80[Formula: see text]V and 90[Formula: see text]V) in phosphoric acid and two voltages (60[Formula: see text]V and 70[Formula: see text]V) in oxalic acid. The aluminum and PAA samples were characterized by SEM and XRD while the pore arrangement, pore density, pore diameter, pore circularity and pore regularity were also analyzed. XRD spectra confirmed the aluminum to be crystalline with the dominant plane being (220), the Cu-rich phase have an average particle size of [Formula: see text][Formula: see text]nm uniformly distributed within the Al matrix of 0.4-[Formula: see text]m grain size. The steady-state current density through the anodization increased by 117% and 49% for oxalic and phosphoric acids, respectively, for 10[Formula: see text]V increase (from 60 to 70 V) in anodization voltage. Similarly, the etching rate increased by 100% for oxalic acid and by 40% for phosphoric acid which are responsible for 47% and 29% decreases in anodization duration, respectively. The highest value of circularity obtained for anodized Al–0.5[Formula: see text]wt.% Cu formed in oxalic acid at 60[Formula: see text]V was 0.86, and it was 0.80 for the phosphoric acid at 90[Formula: see text]V. Anodization of Al–0.5[Formula: see text]wt.% Cu films allows the formation of circular pores directly on [Formula: see text]-type silicon wafers which is of importance for future nanofabrication of advanced electronics. The results of anodized Al–0.5[Formula: see text]wt.% Cu thin film were compared with other anodized systems such as anodized pure Al and Al doped with Si.