Ultraviolet Photoluminescence of Carbon Nanospheres and its Surface Plasmon-Induced Enhancement

Coupling solar-driven photothermal effect into photocatalysis for sustainable water treatment

Effectively harnessing renewable and inexhaustible solar radiation for energy conversion has attracted significant research interest in the past decade. Solar thermal conversion, as a ubiquitous phenomenon, can be implemented to evaporate water and concurrently boost photocatalytic performance for addressing freshwater scarcity and energy crisis. Most recently, solar water evaporation accompanied by photocatalytic degradation, sterilization, and hydrogen production has been proposed as a promising avenue to endow new vitality into the field of clean water and energy production. Driven by the advances of rationally designed solar-powered functional materials, a large variety of photothermal-coupled photocatalysis technologies have been exploited. In this context, it is imperative to summarize the recent progress and discuss the challenges in this multidisciplinary field. Herein, we overview photothermal materials based on various fundamental principles and highlight emerging applications in the areas of solar water evaporation, water purification, and solar-driven energy production. Furthermore, the challenges and perspectives toward both fundamental research and practical applications are also proposed. It is envisioned that this review can provide insightful suggestions to further advance the development of integrated solar thermal driven water evaporation and photocatalytic systems to fulfill concurrent energy conversion and environmental applications.

A 3D C@TiO2 multishell nanoframe for simultaneous photothermal catalytic hydrogen generation and organic pollutant degradation

Rapid heat loss and fast charge carrier recombination constitute two crucial issues that hinder the development of efficient solar energy utilization and conversion over the semiconductor in a photothermal catalytic system. Inspired by energy production from waste water, we designed an advanced 3D C@TiO₂ multishell nanoframe (MNF) photocatalyst. Its unique structural features of heat confinement and vibrant photocarrier kinetics lead to excellent photo-thermal conversion for synchronous superior photocatalytic H₂ evolution (503 μmol g^-1h^-1) and 98.2% RhB removal without the use of any co-catalyst and sacrificial reagent under simulated sunlight irradiation (AM 1.5G). Mechanism exploration reveals that the difference between the inner and outer gas pressure formed inside C@TiO₂ precursor facilitates the selective cleavage of outer TiO₂ layers at selected temperatures during calcination. Synergistic effects between residual carbon core and multi-shelled TiO₂ framework endow C@TiO₂ MNF with excellent heat confinement and vibrant photocarrier kinetics. Such MNF photo-thermocatalyst concept provides a novel strategy for effective utilization of solar energy, and this work may open a novel avenue towards advanced nanostructures for efficient waste-to-energy conversion.

Amphiphilicity-adaptable graphene quantum dots to stabilize pH-responsive pickering emulsions at a very low concentration

HYPOTHESIS

Stimuli-responsive Pickering emulsions have attracted considerable interest due to their widespread potential applications. Especially pH-responsive behavior could be easily implemented. In this work, we reported a pH-responsive Pickering emulsion based on amphiphilic graphene quantum dots at a low concentration which shows a great potential from the environmental and economic perspective. The stimuli responsive properties would make the smart Pickering emulsifiers recyclable and reusable.

EXPERIMENTS

The amphiphilic-adaptable graphene quantum dots functionalized by alkyl groups (C-GQDs) were synthesized by a facile one-step pyrolysis method. The pH-responsive emulsion performances were investigated, and the mechanism of pH-responsive of C-GQDs was studied by dynamic light scattering.

FINDINGS

The amphiphilicity of C-GQDs could be acquired controllably and effectively by this facile one-step pyrolysis method, which are able to stabilize Pickering emulsion at a very low concentration (0.001%). The amphiphilicity of C-GQDs are capable of changing in response to environmental stimuli. When the pH value of aqueous solution adjusts to 2, these C-GQDs aggregate in contrast to their stability in neutral condition due to the alternation of surface charges. The pH-responsive aggregation/ dispersion behavior of C-GQDs allows us to tune the interactions between oil-in-water emulsion droplets without introduction of destabilization agents. This will provide huge economic benefits in industrial applications in the future.

Ultraviolet Carbon Nanodots Providing a Dual-Mode Spectral Matching Platform for Synergistic Enhancement of the Fluorescent Sensing

The sensing of chromium(VI) (Cr(VI)) is highly desired, due to its toxic and carcinogenic effects upon human health. Fluorescent probes, especially carbon nanodots (CNDs), have been widely used for Cr(VI) sensing via the inner filter effect (IFE). However, improving the sensitivity of these probes remains a difficult issue. In this work, CNDs derived from β-Lactoglobulin were applied as an ultrasensitive fluorescent probe for Cr(VI). With 260 nm excitation, the CNDs showed multi-band emission, including an ultraviolet 360 nm peak. The spectral matching of the CNDs with Cr(VI) led to synergistic suppression of both the excitation and emission light in the fluorescent sensing. As a consequence, the CNDs showed high sensitivity toward Cr(VI), the detection limit reaching as low as 20 nM. Moreover, taking advantage of the multi-emissive property of the CNDs, the synergistic effect was proven in an IFE-based sensing system, which might be extended to the design of other kinds of fluorescent probes.

Deep-Ultraviolet Emissive Carbon Nanodots

Deep-ultraviolet (DUV) emissive carbon nanodots (CNDs) have been designed theoretically and demonstrated experimentally based on the results of first-principles calculations using the density functional theory method. The emission of the CNDs is located in the range from 280 to 300 nm, which coincides well with the results of theoretical calculation results. The photoluminescence (PL) quantum yield (QY) of the CNDs is up to 31.6%, and the strong emission of the CNDs originates from core-state (π-π*) carriers' radiative recombination and surface passivation. Benefiting from the core-state emission and surface group passivation, the emission of the CNDs is independent of the excitation wavelength and ambient solvent. DUV light-emitting diodes (LEDs) have been fabricated based on the DUV emissive CNDs, and the LEDs can be used as the excitation source to excite blue, green, and red CNDs, indicating their potential application in DUV light sources. This work may provide a clue for the designing and realizing of DUV emissive CNDs, thus promising the potential application of CNDs in DUV light-emitting sources.