Unprecedented Ag-Cu2O composited mesocrystals with efficient charge separation and transfer as well as visible light harvesting for enhanced photocatalytic activity

Mechanistic insight into near-infrared light-driven Cu2O/WO2 Ohmic contact photothermal catalysts for high-efficiency antibiotic wastewater purification

Near-infrared (NIR) light-induced photothermal effect is beneficial for accelerating catalytic processes; thus, it is imperative to develop novel photothermal catalysts for promoting practical application. Herein, we synthesized NIR-responsive Cu2O/WO2 Ohmic contact photothermal catalysts through a facile ethylene glycol-assisted liquid-phase reduction method. In this photothermal catalyst, a new-type NIR-responsive Cu2O semiconductor is integrated with an NIR-responsive WO2 semimetal component to form an Ohmic contact, which is more beneficial for simultaneously promoting photocharge separation and enhancing NIR light absorption for a high-efficiency photothermal effect. As expected, the Cu2O/WO2 composite displays higher NIR light-driven photothermal catalytic performance for tetracycline removal from wastewater. Various characterization methods and density functional theory calculations were performed to obtain in-depth mechanistic insights into the NIR light-driven Cu2O/WO2 Ohmic contact photothermal catalysts. Hopefully, this research could provide a useful guideline for researchers focusing on the photothermal engineering of new composite photocatalysts.

Sketching Precursor Evolution to Delineate Growth Pathways for Anatase (TiO2) Crystal Design

Engineering advanced functional materials such as Anatase crystals through the molecular tuning of crystal facets is the current enigma of interest pertinent to solving the structure-property-performance triad. Developing optimal shapes and sizes of crystallite necessitates exploring the nanoscopic growth mechanism via precursor tracking. Here, the tapestry of particles varying in dimensionality (0D-3D), sizes (8-3000 nm), and morphology (aggregated to highly faceted crystals) is generated. To decipher and subsequently modulate the crystallization pathways, high-resolution microscopy (high-resolution transmission electron microscopy(HRTEM) and field emission scanning electron microscopy(FESEM)) is used to sketch time-stamped particle evolution. Interestingly, the studies provide evidence for 4-distinct mechanisms where nanoparticles/nanosheets play direct and/or indirect roles in crystallization through multi-stage aggregation (primary, secondary, and tertiary) beginning with similar growth solutions. The four distinct pathways elucidate bulk particle formation via non-classical routes of crystallization including nanosheet alignment and aggregation, nanocrystallite formation and fusion, nanobeads formation and attachment, and direct nanosheet incorporation in bulk crystals. Notably, the direct evidence of flexible-partially-ordered nanosheets being subsumed along the contours of bulk crystals is captured. These novel syntheses generated uniquely faceted particles with high-indexed surface planes such as (004), (200), and (105), amenable to photocatalytic applications.

Multifunctional modification polyester with Au@Cu2O-ZnO ternary heterojunction fabricated by in situ polymerization

In situ polymerization has been proven to be an effective method to introduce functional materials into polymers. In this work, a nano-heterojunction material was prepared successfully and evenly dispersed in PET by in situ polymerization methods to yield multifunctionally modified PET. The modified PET fibers showed excellent antibacterial activity and strong moisture absorption and perspiration, which could efficiently expel moisture from humans. Significantly, these prepared PET textiles demonstrate a strong safety without any cytotoxicity. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the uniform dispersion of heterojunctions and well-defined truncated octahedra including nano-gold rods. A series of characterizations including FTIR, XPS, XRD and DSC showed that the nano-heterojunction participates in the reaction during polymerization. It is interesting that the SEM images of the modified PET fiber presented an intriguing organ fold structure, which makes a significant contribution to moisture absorption and perspiration. The formation mechanism is discussed preliminarily.

Plasmonic Ag@Cu2O core-shell nanostructures exhibiting near-infrared photothermal effect

This work was devoted to the investigation of the optical properties, structural characterization, and photothermal conversion performance of Ag@Cu2O nanostructures. The selection of anisotropic silver core, specifically Ag nanocubes, was driven by the possibility to tune LSPR across a broader range of the electromagnetic spectrum. The thickness of the Cu2O shell was intentionally changed through the variation in the Cu salt to the metal core nanoparticles ratios. The LSPRs of Ag(nanocube)@Cu2O core-shell nanoparticles can be fine-tuned to the spectral region to become resonant with the excitation wavelengths of 808 nm NIR laser. Due to the high refractive index of the deposited Cu2O, the redshifts of the plasmon band wavelength in the extinction spectra were observed. Consequently, the photothermal activities of the Ag(nanocube)@Cu2O core-shell NPs have been controlled by the shell thickness at the nanoscale. Ag@Cu2O nanoparticles with thickest shell (∼70 nm) exhibit the most efficient NIR photothermal effect under the irradiation of 808 nm laser at ambient conditions. Results of this work demonstrate that Ag@Cu2O hetero-nanostructures may be optimized and used for the efficient transformation of light into other forms of energy, specifically heat.

Light-Powered Self-Adaptive Mesostructured Microrobots for Simultaneous Microplastics Trapping and Fragmentation via in situ Surface Morphing

Microplastics, which comprise one of the omnipresent threats to human health, are diverse in shape and composition. Their negative impacts on human and ecosystem health provide ample incentive to design and execute strategies to trap and degrade diversely structured microplastics, especially from water. This work demonstrates the fabrication of single-component TiO2 superstructured microrobots to photo-trap and photo-fragment microplastics. In a single reaction, rod-like microrobots diverse in shape and with multiple trapping sites, are fabricated to exploit the asymmetry of the microrobotic system advantageous for propulsion. The microrobots work synergistically to photo-catalytically trap and fragment microplastics in water in a coordinated fashion. Hence, a microrobotic model of "unity in diversity" is demonstrated here for the phototrapping and photofragmentation of microplastics. During light irradiation and subsequent photocatalysis, the surface morphology of microrobots transformed into porous flower-like networks that trap microplastics for subsequent degradation. This reconfigurable microrobotic technology represents a significant step forward in the efforts to degrade microplastics.

Chloride-ion-directed synthesis of plate-like Cu2O mesocrystals for effective nitrogen fixation

Cuprous oxide (Cu₂O) mesocrystals, which are composed of numerous nanocrystals with a common crystallographic orientation, are supposed to possess superior photocatalytic abilities than the normal constructions, but very few of them have been reported to date. In this work, plate-like Cu₂O mesocrystals were successfully fabricated via a facile one-pot wet chemical strategy. Unlike the commonly used polymers or small molecules, chloride ions (Cl^-) were employed as structure-directing agents and played the main role in the Cu₂O mesocrystal formation. The formation mechanism was interpreted as follows: the presence of Cl^- inhibited the formation of CuO and Cu by forming the intermediate product CuCl, which was further hydrolyzed to Cu₂O nanocrystals. Cl^- tended to adsorb on the (111) facets of the formed Cu₂O nanocrystals and stabilize them. Then the Cu₂O nanocrystals were aligned side by side through the unabsorbed side faces, leading to mutual nanocrystals orientation and crystallographic lock-in, facilitating the formation of plate-like Cu₂O mesocrystals. The polymer, polyacrylamide (PAM), also promoted the mesocrystals formation by serving as a stabilizer and fixed the crystallographic orientation of the Cu₂O nanocrystals during their orderly stacking process. The plate-like Cu₂O mesocrystals showed a long decay time and pronounced performance toward the visible-light-driven photocatalytic reduction of N₂ into NH₃. This research may stimulate in-depth investigations into the exploration of new synthetic methods for the design and construction of novel mesocrystals.

Apple-like Zinc-Oxide Mesocrystals as Robust and Versatile Photocatalysts for Efficient Degradation of Eight Different Organic Dyes

The discovery of efficient photocatalysts is a promising key approach to solve the environmental crisis caused by hazardous organic dyes. Herein, we have for the first time created ZnO mesocrystals with a novel apple-like morphology. We have developed a one-pot biomineralization route to synthesize ZnO nanostructures at room temperature by using the rod-like protein collagen as the template. The shape of ZnO mesocrystals can be conveniently tuned from fusiform-like and kiwi-like to orange-like, apple-like, and snack-like structures. The apple-like ZnO mesocrystals show a significantly better photodegradation efficiency than the commercial ZnO powder as well as other nanostructured ZnO materials for both rhodamine B (RhB) and methyl orange (MO). Furthermore, the apple-like zinc-oxide mesocrystals can degrade all of the tested eight different types of organic dyes (RhB, rhodamine 6G, methylene blue, Coomassie brilliant blue R250, BPB, MO, Li Chunhong S, and carmine) simply under the exposure of sunlight, demonstrating their superior photodegradation prowess, environmental amiability, and energy-saving features. The novel robust and versatile photocatalyst has greatly advanced our abilities for the elimination of organic dyes. The green, one-pot strategy provides a convenient method for the construction of novel metal-oxide nanostructures with promising applications in environmental protection.