Towards visible light hydrogen generation: quantum dot-sensitization via efficient light harvesting of hybrid-TiO2

Bottom-up synthesis of nitrogen and oxygen co-decorated carbon quantum dots with enhanced DNA plasmid expression

In this paper, a bottom-up hydrothermal route is reported for the synthesis of oxygen and nitrogen co-decorated carbon quantum dots (CQDs) using ammonium hydrogen citrate (AHC) as a single precursor. DLS data approved the formation of 4.0 nm (average size) CQDs. XRD pattern shows the interlayer spacing (002) of 3.5 Å for CQDs, which is exactly the same as that of crystalline graphite. XPS and FTIR spectra verified the formation of oxygen and nitrogen functional groups on the CQDs surface. Co-decorated carboxyl, hydroxyl and amine groups on the CQDs surfaces make them as promising polyelectrolyte for gene delivery. Toxicity assay showed a survival rate of 70% under different incubation times and up to 500 μg/mL. The highly water-soluble, stable fluorescence and low toxic CQDs increased the gene expression of DNA plasmid in E. coli bacteria 4-fold more than the control group.

Low field magneto-tunable photocurrent in CoFe2O4 nanostructure films for enhanced photoelectrochemical properties

Efficient solar to hydrogen conversion using photoelectrochemical (PEC) process requires semiconducting photoelectrodes with advanced functionalities, while exhibiting high optical absorption and charge transport properties. Herein, we demonstrate magneto-tunable photocurrent in CoFe₂O₄ nanostructure film under low applied magnetic fields for efficient PEC properties. Photocurrent is enhanced from ~1.55 mA/cm² to ~3.47 mA/cm² upon the application of external magnetic field of 600 Oe leading to ~123% enhancement. This enhancement in the photocurrent is attributed to the reduction of optical bandgap and increase in the depletion width at CoFe₂O₄/electrolyte interface resulting in an enhanced generation and separation of the photoexcited charge carriers. The reduction of optical bandgap in the presence of magnetic field is correlated to the shifting of Co²⁺ ions from octahedral to tetrahedral sites which is supported by the Raman spectroscopy results. Electrochemical impedance spectroscopy results confirm a decrease in the charge transfer resistance at the CoFe₂O₄/electrolyte interface in the presence of magnetic field. This work evidences a coupling of photoexcitation properties with magnetic properties of a ferromagnetic-semiconductor and the effect can be termed as magnetophototronic effect.

Highly transparent poly(glycidyl methacrylate-co-acryloisobutyl POSS) for 100 μm-thick submicron patterns with an aspect ratio over 100

This is the first report on the fabrication of defect-free submicron structures with more than 100 μm thickness and an aspect ratio over 100. Highly transparent poly(glycidyl methacrylate-co-acryloisobutyl POSS) (PGP) was synthesized via radical polymerization. The mechanical properties of the PGP submicron structure displayed a Young's modulus of 6.09 GPa and a hardness of 0.16 GPa, 4.2 and 8 times, respectively, than those of SU8 nanopatterns. These enhancements enable the utilization of ultrathick 2D-/3D-submicron structures as an ideal platform for microelectromechanical systems, big data storage systems, energy devices, etc.

Design and Synthesis of Cu@CuS Yolk-Shell Structures with Enhanced Photocatalytic Activity

Non-spherical Cu@CuS yolk-shell structures are successfully obtained using Cu₂O cube templates in a process combining rapid surface sulfidation followed by disproportionation of the Cu₂O core upon treatment with a hydrochloric acid solution. By employing the above method, Cu@CuS yolk-shell structures with different morphologies, including octahedral, truncated octahedral, and cuboctahedral shapes, can be synthesized. The void space within the hollow structures provides a unique confined space, where the metallic copper present in the core of a shell can be protected from agglomeration and oxidation. Furthermore, the presence of metal copper in these hollow structures contributes to improvement in the photocatalytic properties of these materials. The application of these Cu@CuS structures indeed shows clearly improved photocatalytic performance.

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion

This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic-photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.

Metal free earth abundant elemental red phosphorus: a new class of visible light photocatalyst and photoelectrode materials

A proposed photocatalytic mechanism for the photodegradation of RhB over RP under visible photoirradiation.

Light illuminated α-Fe2O3/Pt nanoparticles as water activation agent for photoelectrochemical water splitting

The photoelectrochemical (PEC) water splitting is hampered by strong bonds of H₂O molecules and low ionic conductivity of pure water. The photocatalysts dispersed in pure water can serve as a water activation agent, which provides an alternative pathway to overcome such limitations. Here we report that the light illuminated α−Fe₂O₃/Pt nanoparticles may produce a reservoir of reactive intermediates including H₂O₂, ·OH, OH⁻ and H⁺ capable of promoting the pure water reduction/oxidation half−reactions at cathode and highly photocatalytic−active TiO₂/In₂S₃/AgInS₂ photoanode, respectively. Remarkable photocurrent enhancement has been obtained with α−Fe₂O₃/Pt as water activation agent. The use of α−Fe₂O₃/Pt to promote the reactivity of pure water represents a new paradigm for reproducible hydrogen fuel provision by PEC water splitting, allowing efficient splitting of pure water without adding of corrosive chemicals or sacrificial agent.

TiO2 nanotubes sensitized with CdSe via RF magnetron sputtering for photoelectrochemical applications under visible light irradiation

Highly ordered TiO₂ NT arrays were easily decorated with CdSe via RF magnetron sputtering.

p-Doped three-dimensional graphene nano-networks superior to platinum as a counter electrode for dye-sensitized solar cells

A chemical vapor deposition-grown p-doped three-dimensional graphene nano-network-based DSSC exhibits 6% greater photoconversion efficiency than a Pt-based DSSC.