Enhanced Photocatalytic Hydrogen Evolution of In2S3 by Decorating In2O3 with Rich Oxygen Vacancies

The hydrogen (H2) evolution rates of photocatalysts suffer from weak oxidation and reduction ability and low photogenerated charge carrier separation efficiency. Herein, by combining band-gap structure optimization and vacancy modulation through a one-step hydrothermal method, In2O3 containing oxygen vacancy (Ov/In2O3) is simply introduced into In2S3 to promote photocatalytic hydrogen evolution. Specifically, the change in the sulfur source ratio can induce the coexistence of Ov/In2O3 and In2S3 in a high-temperature hydrothermal process. Under light irradiation, In2S3@Ov/In2O3-0.1 nanosheets hold a remarkable average H2 evolution rate up to 4.04 mmol g-1 h-1, which is 32.14, 11.91, and 2.25-fold better than those of pristine In2S3, In2S3@Ov/In2O3-0.02, and In2S3@Ov/In2O3-0.25 nanosheets, respectively. The ultraviolet-visible (UV-vis) diffuse reflectance and photoluminescence (PL) spectra reveal that the formation of Ov/In2O3 in In2S3 optimizes the band-gap structure and accelerates the migration of the photogenerated charge carrier of In2S3@Ov/In2O3-x nanosheets, respectively. Both the enhancement of oxidation and reduction ability and photogenerated charge carrier separation ability are responsible for the remarkable improvement in photocatalytic H2 evolution performance. This work provides a new strategy to prepare a composite of metal sulfide and metal oxide through a one-step hydrothermal method.

Gold@mesoporous polydopamine nanoparticles modified self-healing hydrogel for sport-injuring therapy

Sports-related damage is a prevalent issue, which a combination therapy including photothermal irradiation, self-healing dressing and antibacterial treatment is an effective way to rehabilitate it. In the study, a multifunctional hydrogel was developed to meet the requirement. Firstly, mesoporous polydopamine (MPDA) was prepared, where gold nanoparticles (Au NPs) were formed in its mesoporous structure, to construct Au@MPDA NPs with nanosize about 200 nm. Synergetic and efficient photothermal effect was achieved by the combination of the two photothermal agents. The Au@MPDA NPs were then added to modify polyvinyl alcohol-carboxymethyl chitosan-borax (PCB) hydrogel. Via rheological property characterization, cell experiments and antibacterial evaluation, high photothermal efficiency and effective antibacterial activity of Au@MPDA@PCB hydrogel was obtained with the aid of Au@MPDA NPs, together with self-healing property. When treated in motion-related tissue, the modified hydrogel showed excellent adaptive property and photothermal effect in situ. This study is beneficial for developing a novel rehabilitation treatment strategy for sports-related injuries.

Plasmonic Nanocrystal Assembly-Semiconductor Hybrids for Boosting Visible to Near-Infrared Photocatalysis

Plasmonic metal-semiconductor hybrid photocatalysts have received much attention because of their wide light harvesting range and efficient charge carrier generation capability originating from plasmon energy transfer. Here, we introduce a plasmonic metal-semiconductor hybrid nanostructure consisting of a Au core-satellite assembly and crystalline TiO2. The formation of Au@TiO2-Au core-satellite assemblies using TiO2 as a spacer and the subsequent growth of outer TiO2 shells on the core-satellite assemblies, followed by calcination, successfully generated Au core-satellite assembly@TiO2 nanostructures. Exquisite control over the growth of the TiO2 interlayer enabled the regulation of the gap distance between the core and satellite Au nanocrystals within the same hybrid morphology. Due to the structural controllability of the present approach, the gap-distance-dependent plasmonic and photocatalytic properties of the hybrid nanostructures could be explored. The nanostructures possessing the most closely arranged Au nanocrystals showed high photocatalytic activity under visible to near-infrared light irradiation, which can be attributed to strong plasmon coupling between the core and satellite Au nanocrystals that can expedite the formation of intense plasmon energy and its transfer to TiO2.

A Bimetallic Organic Framework with Mn in MIL-101(Cr) for Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) show excellent performance in terms of specific capacity and energy density. However, the cyclic stability of LSBs is compromised due to the "shuttle effect", which hinders the practical applications of LSBs. Herein, a metal-organic framework (MOF) based on Cr ions as the main body composition, commonly known as MIL-101(Cr), was utilized to minimize the shuttle effect and improve the cyclic performance of LSBs. To obtain MOFs with a certain adsorption capacity for lithium polysulfide and a certain catalytic capacity, we propose an effective strategy of incorporating sulfur-loving metal ions (Mn) into the skeleton to enhance the reaction kinetics at the electrode. Based on the oxidation doping method, Mn²⁺ was uniformly dispersed in MIL-101(Cr) to produce bimetallic Cr₂O₃/MnO_x as a novel sulfur-carrying cathode material. Then, a sulfur injection process was carried out by melt diffusion to obtain the sulfur-containing Cr₂O₃/MnO_x-S electrode. Moreover, an LSB assembled with Cr₂O₃/MnO_x-S showed improved first-cycle discharge (1285 mAh·g^-1 at 0.1 C) and cyclic performance (721 mAh·g^-1 at 0.1 C after 100 cycles), and the overall performance was much better than that of monometallic MIL-101(Cr) as a sulfur carrier. These results revealed that the physical immobilization method of MIL-101(Cr) positively affected the adsorption of polysulfides, while the bimetallic composite Cr₂O₃/MnO_x formed by the doping of sulfur-loving Mn²⁺ into the porous MOF produced a good catalytic effect during LSB charging. This research provides a novel approach for preparing efficient sulfur-containing materials for LSBs.

Hybrid Plasmonic Nanomaterials for Hydrogen Generation and Carbon Dioxide Reduction

The successful development of artificial photosynthesis requires finding new materials able to efficiently harvest sunlight and catalyze hydrogen generation and carbon dioxide reduction reactions. Plasmonic nanoparticles are promising candidates for these tasks, due to their ability to confine solar energy into molecular regions. Here, we review recent developments in hybrid plasmonic photocatalysis, including the combination of plasmonic nanomaterials with catalytic metals, semiconductors, perovskites, 2D materials, metal-organic frameworks, and electrochemical cells. We perform a quantitative comparison of the demonstrated activity and selectivity of these materials for solar fuel generation in the liquid phase. In this way, we critically assess the state-of-the-art of hybrid plasmonic photocatalysts for solar fuel production, allowing its benchmarking against other existing heterogeneous catalysts. Our analysis allows the identification of the best performing plasmonic systems, useful to design a new generation of plasmonic catalysts.

Investigation of the local photothermal effects by fabricating CQDs/Au/TiO2 photoelectrode in PEC water splitting system

The high efficiency of photoanode material is great significant for photoelectrochemical (PEC) water splitting. Herein, CQDs/Au/TiO2 nanorods array composite photoanode was constructed with special attention to local photothermal effects. The...

Gold Nanorods: The Most Versatile Plasmonic Nanoparticles

Gold nanorods (NRs), pseudo-one-dimensional rod-shaped nanoparticles (NPs), have become one of the burgeoning materials in the recent years due to their anisotropic shape and adjustable plasmonic properties. With the continuous improvement in synthetic methods, a variety of materials have been attached around Au NRs to achieve unexpected or improved plasmonic properties and explore state-of-the-art technologies. In this review, we comprehensively summarize the latest progress on Au NRs, the most versatile anisotropic plasmonic NPs. We present a representative overview of the advances in the synthetic strategies and outline an extensive catalogue of Au-NR-based heterostructures with tailored architectures and special functionalities. The bottom-up assembly of Au NRs into preprogrammed metastructures is then discussed, as well as the design principles. We also provide a systematic elucidation of the different plasmonic properties associated with the Au-NR-based structures, followed by a discussion of the promising applications of Au NRs in various fields. We finally discuss the future research directions and challenges of Au NRs.

Near-infrared light-responsive photothermal α-Fe2O3@Au/PDA core/shell nanostructure with on-off controllable anti-bacterial effects

Antimicrobial materials are expected to be alternatives for antibiotics against multidrug-resistant bacteria. In this paper, non-spherical α-Fe₂O₃@Au/PDA core/shell nanoparticles with tunable shapes are synthesized by a one-step in situ oxidation-redox polymerization method toward near infrared light-responsive antibacterial therapy. The thickness and composition of the Au/PDA hybrid shell can be controlled by varying the concentration of HAuCl₄ and the dopamine precursor. Owing to the wonderful photothermal characteristics originating from the Au/PDA shell, the spindle α-Fe₂O₃@Au/PDA core shell nanoparticles exhibit excellent photothermal sterilization effects against both Escherichia coli and Staphylococcus aureus at low concentrations. Meanwhile, the NIR photothermal induced bactericidal performance indicates that α-Fe₂O₃@Au/PDA hybrid particles with tunable non-spherical shapes possess unique controllable antibacterial effects. As a result, this finding provides a simple strategy for fabricating high performance photothermal antibacterial agents and the final products possess high potential in synergistic antimicrobial therapy.

Can Plasmonic Effect Cause an Increase in the Catalytic Reduction of p-nitrophenol by Sodium Borohydride over Au Nanorods?

The catalytic reduction of p-nitrophenol (4-NP) to 4-aminopyridine (4-AP) over Au nanoparticles can be increased by light illumination. Whether this is caused by the plasmonic effect remains unclear. The present research carried out a careful examination of the effects of light illumination and temperature on the catalytic conversion of 4-NP to 4-AP over Au nanorods. It was seen that light illumination has no effect on the apparent activation energy; this indicates that the catalytic mechanism is unchanged and the activity increase cannot be attributed to the effect of hot electrons. Based on the simulation of finite-difference time domain, the theoretical analysis also showed that plasmonic heating cannot play a major role. Thermographic mapping showed that the temperature of water solutions shows an increase under light illumination. By taking this temperature increase into consideration, the light-induced increase of the 4-NP to 4-AP conversion can agree well with dark catalysis, which cannot be attributed to the plasmonic effects of the Au nanorods.

Synthesis of Au@TiO2 core-shell nanoparticles with tunable structures for plasmon-enhanced photocatalysis

Plasmonic metal-semiconductor nanocomposites, especially those with core-shell nanostructures, have received extensive attention as they can efficiently expand light absorption and accelerate electron-hole separation thus improving the photocatalytic efficiency. However, controlled synthesis and structure manipulation of plasmonic metal-semiconductor nanocomposites still remain a significant challenge. Herein, a simple and universal method has been developed for the preparation of plasmonic Au@TiO₂ core-shell nanoparticles. Using such a method, uniform TiO₂ shells are successfully coated on Au nanoparticles with various morphologies including nanorods, nanocubes, and nanospheres, and the thickness and crystallinity of the TiO₂ shell can be simply tuned by adjusting the pH value and thermal treatment, respectively. Furthermore, the influence of the morphology of the Au core and the thickness and crystallinity of the TiO₂ shell on the photocatalytic performance of Au@TiO₂ towards the photodegradation of methylene blue is systematically explored. It is found that Au@TiO₂ NPs with nanorod morphology and crystalline TiO₂ shells display the best performance, which is 5 times higher than that of bare Au nanoparticles. This work provides a facile strategy for the fabrication of plasmonic core-shell nanostructures that show excellent performance in plasmon-enhanced photocatalysis.

Fabrication of CdTe QDs/BiOI-Promoted TiO2 Hollow Microspheres with Superior Photocatalytic Performance Under Simulated Sunlight

Hollow and heterostructured architectures are recognized as an effective approach to improve photocatalytic performance. In this work, ternary TiO₂/CdTe/BiOI with hollow structure was constructed via a step-by-step method. In addition, the effect of TiO₂ structural regulation and the energy band alignment of BiOI and CdTe quantum dots (CdTe QDs) with TiO₂ in TiO₂/CdTe/BiOI on photocatalytic dye removal were also studied. The results reveal that the TiO₂/CdTe/BiOI heterostructures with hollow substrates exhibit much higher photocatalytic activities than pure TiO₂, P25, TiO₂/CdTe, and TiO₂/BiOI and ternary TiO₂/CdTe/BiOI with solid substrates. For TiO₂(H)/CdTe/BiOI, several synergistic factors may be responsible for the remarkable visible-light photodegradation performance, such as strong visible-light absorption by BiOI and larger specific surface area.

Amorphous TiO2 nanostructures: synthesis, fundamental properties and photocatalytic applications

In this review, we mainly highlight the advances made in the development of amorphous TiO₂ nanostructures for photocatalysts. Some perspectives on the challenges and new direction are also discussed.

Recent advances and strategies to tailor the energy levels, active sites and electron mobility in titania and its doped/composite analogues for hydrogen evolution in sunlight

Hydrogen production through photocatalytic water reduction, a potential path for future renewable and sustainable energy generation.

Facile one-step synthesis of TiO2/Ag/SnO2 ternary heterostructures with enhanced visible light photocatalytic activity

Novel TiO2/Ag/SnO2 composites were successfully prepared by a facile one-step reduction approach using stannous chloride as both SnO2 precursor and reducing agent. The Ag nanoparticles with sizes of 2.04-3.94 nm were located on TiO2 matrix and immobilized by the surrounded SnO2. The resulted TiO2/Ag/SnO2 nanocomposites were used as photocatalyst for photodegradation of methylene blue under visible light. The experimental results demonstrated that the visible light photocatalytic activity of the TiO2/Ag/SnO2 was significantly enhanced in comparison with the individual TiO2 or the binary composite (TiO2/Ag or TiO2/SnO2) and the degradation rate was up to about 9.5 times that of commercial TiO2. The photocatalytic activity of the TiO2/Ag/SnO2 composites could be well controlled by simply tuning the dosages of Ag precursor and the optimized activity of the composites was obtained when the dosage of Ag precursor was 2%. Moreover, the TiO2/Ag/SnO2 photocatalyst exhibited high stability for degradation of methylene blue even after four successive cycles.