Broadband radar absorbing metamaterial based on Al @SiO2 conductive composite film.

Artificially designed metamaterial structures can manipulate electromagnetic waves, endowing them with exotic physical properties that are not found in natural materials, such as negative refractive index, superlens, and inverse Doppler effect. These characteristics are widely applied in various engineering and military applications. Due to increasingly complex application environments and innovation in radar detection technology, the combination of broadband absorption performance under thin thickness and efficient preparation methods at low cost is often the focus of research on new generation stealth materials. Here, we propose Al@SiO2 composite conductive film metamaterial (Al@SiO2 CCFM) to achieve wideband absorption of electromagnetic waves. This metamaterial structure combines two resonant units, resulting in three absorption bands in the absorption curve. The results show that the absorption rate of the metamaterial is above 90% in the frequency range of 10.6 GHz to 26.0 GHz. The resonance mechanism between multiple structures is a prerequisite for achieving wideband absorption. The materials Al and SiO2 used in Al@SiO2 CCFM are inexpensive and abundant, and the fabrication method is simple. Therefore, they hold great potential for large-scale applications in the multispectral stealth and electromagnetic shielding field.

Study on a Pig Vocalization Classification Method Based on Multi-Feature Fusion.

To improve the classification of pig vocalization using vocal signals and improve recognition accuracy, a pig vocalization classification method based on multi-feature fusion is proposed in this study. With the typical vocalization of pigs in large-scale breeding houses as the research object, short-time energy, frequency centroid, formant frequency and first-order difference, and Mel frequency cepstral coefficient and first-order difference were extracted as the fusion features. These fusion features were improved using principal component analysis. A pig vocalization classification model with a BP neural network optimized based on the genetic algorithm was constructed. The results showed that using the improved features to recognize pig grunting, squealing, and coughing, the average recognition accuracy was 93.2%; the recognition precisions were 87.9%, 98.1%, and 92.7%, respectively, with an average of 92.9%; and the recognition recalls were 92.0%, 99.1%, and 87.4%, respectively, with an average of 92.8%, which indicated that the proposed pig vocalization classification method had good recognition precision and recall, and could provide a reference for pig vocalization information feedback and automatic recognition.

Decrypting the Electron-Withdrawing Effect of Au-Decorated Bi2 O3 for Efficient CO2 -to-Formate Electroreduction.

Although the electron-withdrawing effect of gold (Au) is highlighted in catalytic reactions, its enhancement mechanism for electron transport, especially in the electrochemical process, is still unclear. Herein, Au-decorated Bi2 O3 (Au-Bi2 O3 ) is proposed as a proof-of-concept to investigate the electron-withdrawing effect in the electrocatalytic CO2 reduction reaction (eCO2 RR) process. Evidence from in situ Raman spectra and in situ XRD tests reveals that, compared to Bi2 O3 , Bi species in Au-Bi2 O3 can be reduced to metallic Bi more rapidly and more easily driven by the electron-withdrawing effect of Au. The XPS tests after eCO2 RR further validates the transformation from Bi3+ to Bi0 in Au-Bi2 O3 is more complete. Meanwhile, in the in situ Fourier transform infrared (FTIR) spectra, the key intermediates (CO2 *- and OCHO*- ) appear at the more positive potential, indicating that metallic Bi is favorable for eCO2 RR due to the lower energy barrier as corroborated by density function theory (DFT) calculations. Au don't directly participate in the conversion from CO2 to formate as the reaction sites, but utilize the electron-withdrawing effect to motivate Bi-sites to deliver higher catalytic activity and higher selectivity to formate at a lower applied potential. This study not only has an insight into the electron-withdrawing effect of Au on the eCO2 RR process, but also develops a new perspective for engineering electron-withdrawing effect in electrocatalysts for high-efficient CO2 -to-formate conversion.

Electronic Structure Modulation Induced by Cobalt-doping and Lattice-Contracting on Armor-Like Ruthenium Oxide Drives pH-Universal Oxygen Evolution.

Exquisite design of RuO2 -based catalysts to simultaneously improve activity and stability under harsh conditions and reduce the Ru dosage is crucial for advancing energy conversion involving oxygen evolution reaction (OER). Herein, a distinctive cobalt-doped RuOx framework is constructed on Co3 O4 nanocones (Co3 O4 @CoRuOx ) as a promising strategy to realize above urgent desires. Extensive experimental characterization and theoretical analysis demonstrate that cobalt doped in RuOx lattice brings the oxygen vacancies and lattice contraction, which jointly redistribute the electron configuration of RuOx . The optimized d-band center balances the adsorption energies of oxygenated intermediates, lowing the thermodynamical barrier of the rate-determining step; and meanwhile, the over-oxidation and dissolution of Ru species are restrained because of the p-band down-shifting of the lattice oxygen. Co3 O4 @CoRuOx with 3.7 wt.% Ru delivers the extremely low OER overpotentials at 10 mA cm-2 in alkaline (167 mV), neutral (229 mV), and acidic electrolytes (161 mV), and super operating stability over dozens of hours. The unprecedented activity ranks first in all pH-universal OER catalysts reported so far. These findings provide a route to produce robust low-loading Ru catalysts and an engineering approach for regulating the central active metal through synergy of co-existing defects to improve the catalytic performance and stability.

Electronic Modulation Induced by Ni-VN Heterojunction Reinforces Electrolytic Hydrogen Evolution Coupled with Biomass Upgrade.

The renewable electricity-driven hydrogen evolution reaction (HER) coupled with biomass oxidation is a powerful avenue to maximize the energy efficiency and economic feedback, but challenging. Herein, porous Ni-VN heterojunction nanosheets on nickel foam (Ni-VN/NF) are constructed as a robust electrocatalyst to simultaneously catalyze HER and 5-hydroxymethylfurfural electrooxidation reaction (HMF EOR). Benefiting from the surface reconstruction of Ni-VN heterojunction during the oxidation process, the derived NiOOH-VN/NF energetically catalyzes HMF into 2,5-furandicarboxylic acid (FDCA), yielding the high HMF conversion (>99%), FDCA yield (99%), and Faradaic efficiency (>98%) at the lower oxidation potential along with the superior cycling stability. Ni-VN/NF is also surperactive for HER, exhibiting an onset potential of ≈0 mV and Tafel slope of 45 mV dec-1 . The integrated Ni-VN/NF||Ni-VN/NF configuration delivers a compelling cell voltage of 1.426 V at 10 mA cm-2 for the H2 O-HMF paired electrolysis, about 100 mV lower than that for water splitting. Theoretically, for Ni-VN/NF, the superiority in HMF EOR and HER is mainly dominated by the local electronic distribution at the heterogenous interface, which accelerates the charge transfer and optimize the adsorption of reactants/intermediates by modulating the d-band center, therefore being an advisable thermodynamic and kinetic process.

CoO-Co Heterojunction Covered with Carbon Enables Highly Efficient Integration of Hydrogen Evolution and 5-Hydroxymethylfurfural Oxidation.

The renewable-energy-driven integration of hydrogen production and biomass conversion into value-added products is desirable for the current global energy transition, but still a challenge. Herein, carbon-coated CoO-Co heterojunction arrays were built on copper foam (CoO-Co@C/CF) by the carbothermal reduction to catalyze the hydrogen evolution reaction (HER) coupled with a 5-hydroxymethylfurfural electrooxidation reaction (HMFEOR). The electronic modulation induced by the CoO-Co heterojunction endows CoO-Co@C/CF with a powerful catalytic ability. CoO-Co@C/CF is energetic for HER, yielding an overpotential of 69 mV at 10 mA·cm-1 and Tafel slope of 58 mV·dec-1. Meanwhile, CoO-Co@C/CF delivers an excellent electrochemical activity for the selective conversion from HMF into 2,5-furandicarboxylic acid (FDCA), achieving a conversion of 100%, FDCA yield of 99.4% and faradaic efficiency of 99.4% at the lower oxidation potential, along with an excellent cycling stability. The integrated CoO-Co@C/CF||CoO-Co@C/CF configuration actualizes the H2O-HMF-coupled electrolysis at a satisfactory cell voltage of 1.448 V at 10 mA·cm-2. This work highlights the feasibility of engineering double active sites for the coupled electrolytic system.

[Enhancing effects of chemical permeation enhancer propylene glycol and ultrasonic technology on transdermal permeation of Baimai Ointment].

This study aimed to improve the transdermal permeation quantity of Baimai Ointment by investigating the enhancing effects of physical and chemical permeation promoting methods on transdermal permeation of Baimai Ointment. The improved Franz diffusion cell method was used for in vitro transdermal experiment. The abdominal skin of mice was used, and the skin was treated with 3% propylene glycol in the chemical enhancement group. Ultrasonic technology was introduced in the physical enhancement group. The conditions of ultrasonic technology were optimized by single factor trial. Taking Q_(EF) and ER as the indexes of penetration promotion performance, the enhancing effects of the two methods were compared. The results showed that the promotion performance of 3% propylene glycol for ammonium glycyrrhizinate, nardosinone and curcumin of the chemical enhancement group were 1.74, 1.60, and 3.73 times higher than those of the blank group, respectively. The overall permeation efficiency of the Baimai Ointment was significantly improved. The comprehensive promoting effect on each component was curcumin>ammonium glycyrrhizinate>nardosinone. In the physical enhancement group, the penetration promoting effect of ultrasonic power 1.0 W was better than that of 2.0 W and 0.5 W, ultrasonic time 5 min was better than 3 min and 8 min, and the ultrasonic frequency 1 MHz was better than 3 MHz. Therefore, the optimal ultrasonic condition was 1.0 W-5 min-1 MHz. Under this condition, in terms of the transdermal permeation for ammonium glycyrrhizinate, the Q_(EF) and ER of the ultrasonic technology were better than those of 3% propylene glycol. In terms of the transdermal permeation for nardosinone and curcumin, the QEF and ER of 3% propylene glycol were better than those of the ultrasonic technology. Therefore, 3% propylene glycol combined with ultrasonic technology can be used to promote permeation of Baimai Ointment that contains both water-soluble and fat-soluble components in the clinical application. This study provides a theoretical basis for the clinical application of Baimai Ointment and other transdermal preparations.

Boron-Induced Electronic-Structure Reformation of CoP Nanoparticles Drives Enhanced pH-Universal Hydrogen Evolution.

Even though transition-metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)-modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B-CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm-2 ). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons' delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics.

NiSe-Ni0.85 Se Heterostructure Nanoflake Arrays on Carbon Paper as Efficient Electrocatalysts for Overall Water Splitting.

Fabricating cost-effective, bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in basic media is critical for renewable energy generation. Here, NiSe/CP, Ni0.85 Se/CP, and NiSe-Ni0.85 Se/CP heterostructure catalysts with different phase constitutions are successfully prepared through in situ selenylation of a NiO nanoflake array oriented on carbon paper (CP) by tuning the original Ni/Se molar ratio of the raw materials. The relationship between the crystal phase component and electrocatalytic activity is systematically studied. Benefiting from the synergetic effect of the intrinsic metallic state, facile charge transport, abundant catalytic active sites, and multiple electrolyte transmission paths, the optimized NiSe-Ni0.85 Se/CP exhibits a remarkably higher catalytic activity for both the HER and OER than single-phase NiSe/CP and Ni0.85 Se/CP. A current density of 10 mA cm-2 at 1.62 V and a high stability can be obtained by using NiSe-Ni0.85 Se/CP as both the cathode and anode for overall water splitting under alkaline conditions. Density functional theory calculations confirm that H and OH- can be more easily adsorbed on NiSe-Ni0.85 Se than on NiSe and Ni0.85 Se. This study paves the way for enhancing the overall water splitting performance of nickel selenides by fabricating heterophase junctions using nickel selenides with different phases.

Generalized Synthesis of Ultrathin Cobalt-Based Nanosheets from Metallophthalocyanine-Modulated Self-Assemblies for Complementary Water Electrolysis.

The development of effective approaches for preparing large-area, self-standing, ultrathin metal-based nanosheets, which have proved to be favorable for catalytic applications such as water electrolysis, is highly desirable but remains a great challenge. Reported herein is a simple and versatile strategy to synthesize ultrathin Co3 O4 and CoP NSs consisting of close-packed nanoparticles by pyrolyzing cobalt(II) phthalocyanine/graphene oxide (CoPc/GO) assemblies in air and subsequent topotactic phosphidation while preserving the graphene-like morphology. The strong π-π stacking interactions between CoPc and GO, and the inhibiting effect of the tetrapyrrole-derived macrocycle for grain growth during the catalytic carbon gasification contribute to the NSs forming. The resulting homologous Co3 O4 and CoP NSs display outstanding catalytic activity in alkaline media toward the oxygen evolution reaction and the hydrogen evolution reaction, respectively, ascribed to the richly exposed active sites, and the expedited electrolyte/ion transmission path. The integrated asymmetrical two-electrode configuration also presents a superior cell voltage of 1.63 V at 10 mA cm-2 for overall water splitting, accompanied with the excellent durability during long-term cycling. Further evidences validate that this strategy is appropriate to fabricate graphene-like ultrathin NSs of many other metal oxides, such as Fe2 O3 , NiO, MoO3 , and mixed-metal oxides, for various applications.

[Rancidness of Armeniacae Semen Amarum involving Bianzhuang Lunzhi].

This article aims to compare the qualities of Armeniacae Semen Amarum before and after rancidness, in order to study the rancidness of Armeniacae Semen Amarum. In the experiment, content of fatty oil, acid value and peroxide value were determined before and after rancidness,respectively. Meanwhile, HPLC, GC-MS were utilized to analyze laetrile and fatty acid components. Besides, colorimeter and e-nose were introduced to quantify and compare "color and odor". A correlation analysis was conducted on the above results. The results showed that color of post-rancidness Armeniacae Semen Amarum changed from yellow to brown, with sour and lower content of laetrile. On the contrary, acid and peroxide values increased significantly, with changes in fatty acid component. There was a considerable correlation between appearance characteristics and changes in internal quality. The "sensory analysis-quality identification system" can provide a certain scientific basis for prediction of the content of chemical components in traditional Chinese medicine, preliminary judgment of quality of traditional Chinese medicine and real-time quality monitoring, which offers us novel ideas and reference for storage principles of traditional Chinese medicines of "pre-event prediction, during-event intervention and post-event identification".

Visible-Light-Induced Self-Cleaning Property of Bi2Ti2O7-TiO2 Composite Nanowire Arrays.

Bi2Ti2O7-TiO2 composite nanowire arrays were prepared via a two-step sequential solvothermal and subsequent calcination process. The morphology and structure of the Bi2Ti2O7-TiO2 composite nanowire array composite were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The UV-visible diffuse reflectance spectroscopy analysis indicated that the absorption spectrum of the Bi2Ti2O7-TiO2 composite nanowire array composite was extended to the visible-light region due to the existence of Bi2Ti2O7. The Bi2Ti2O7-TiO2 composite nanowire arrays exhibit superhydrophilicity with water contact angles of 0° after irradiation with visible light, and the superhydrophilic nature is retained for at least 15 days. This effect enables us to consider self-cleaning applications that do not require permanent UV exposure. Compared to pure Bi2Ti2O7 and TiO2, the vertically aligned Bi2Ti2O7-TiO2 composite nanowire arrays showed more significant visible-light self-cleaning performance due to the synergistic effect of superhydrophilicity and significant photocatalytic activity caused by effective electron-hole separation at the interfaces of the two semiconductors, which was confirmed by the electrochemical analysis and surface photovoltage technique.

Construction of a CoNiHHTP MOF/PHI Z-Scheme Heterojunction for ppb Level NO2 Photoelectric Sensing with 405 nm Irradiation at RT.

Ultrasensitive photoelectric detection of nitrogen dioxide (NO2) with PHI under visible light irradiation at room temperature (RT) remains an ongoing challenge due to the low charge separation and scarce adsorption sites. In this work, a dimensionally matched ultrathin CoNiHHTP MOF/PHI Z-scheme heterojunction is successfully constructed by taking advantage of the π-π interactions existing between the CoNiHHTP MOF and PHI. The amount-optimized heterojunction possesses a record detection limit of 1 ppb (response = 15.6%) for NO2 under 405 nm irradiation at RT, with reduced responsive (3.6 min) and recovery (2.7 min) times, good selectivity and reversibility, and long-time stability (150 days) compared with PHI, even superior to others reported at RT. Based on the time-resolved photoluminescence spectra, in situ X-ray photoelectron spectra, and diffuse reflectance infrared Fourier transform spectroscopy results, the resulting sensing performance is attributed to the favorable Z-scheme charge transfer and separation. Moreover, the Ni nodes favorably present in adjacent metal sites between the lamellae contribute to charge transfer and redistribution, whereas Co nodes could act as selective centers for promoted adsorption of NO2. Interestingly, it is confirmed that the CoNiHHTP MOF/PHI heterojunction could effectively reduce the influence of O2 in the gas-sensitive reaction due to their unique bimetallic (Co and Ni) nodes, which is also favorable for the improved sensing performances for NO2. This work provides a feasible strategy to develop promising PHI-based optoelectronic gas sensors at RT.

Graph autoencoder with mirror temporal convolutional networks for traffic anomaly detection.

Traffic time series anomaly detection has been intensively studied for years because of its potential applications in intelligent transportation. However, classical traffic anomaly detection methods often overlook the evolving dynamic associations between road network nodes, which leads to challenges in capturing the long-term temporal correlations, spatial characteristics, and abnormal node behaviors in datasets with high periodicity and trends, such as morning peak travel periods. In this paper, we propose a mirror temporal graph autoencoder (MTGAE) framework to explore anomalies and capture unseen nodes and the spatiotemporal correlation between nodes in the traffic network. Specifically, we propose the mirror temporal convolutional module to enhance feature extraction capabilities and capture hidden node-to-node features in the traffic network. Morever, we propose the graph convolutional gate recurrent unit cell (GCGRU CELL) module. This module uses Gaussian kernel functions to map data into a high-dimensional space, and enables the identification of anomalous information and potential anomalies within the complex interdependencies of the traffic network, based on prior knowledge and input data. We compared our work with several other advanced deep-learning anomaly detection models. Experimental results on the NYC dataset illustrate that our model works best compared to other models for traffic anomaly detection.

LSPR-dependent SERS performance of silver nanoplates with highly stable and broad tunable LSPRs prepared through an improved seed-mediated strategy.

The application of the silver plates as a proper substrate for surface enhanced Raman spectroscopy (SERS) was performed to give deep insight on LSPR-dependent SERS performance. Firstly, an improved seed-mediated method is developed to synthesize silver nanoplates (NP) with broad-tuning localized surface plasmon resonance (LSPR) and high stability. The LSPR peaks could be tuned in the range from 485 to ∼1200 nm by controlling the experimental parameters. With the treatment of sodium dodecyl sulfate (SDS), silver NPs exhibit high stability for SERS tests. The LSPR-dependent SERS study was performed by taking four typical silver NPs with LSPR peaks at 485 nm, 614 nm, 906 nm and 1130 nm as substrates. Also, two probe molecules, 4-amino-thiophenol (4-ATP) and rhodamine-6G (R-6G), were used, and both the 458 nm and 633 nm lasers were selected as excitation for the LSPR-dependent SERS study. Our results indicated that the SERS performance is largely dependent on the LSPR of the silver NP substrate at a given excitation wavelength. Specifically, the Raman signals were greatly enhanced when the laser excitation line matched (close to the LSPR band) the peak position of LSPR band. When at the excitation of 633 nm, two orders of magnitude stronger SERS signals would be observed for the Ag-614 substrate than that of the Ag-485 and Ag-1130 substrates with their LSPR peak positions far away from 633 nm. The same result can also be observed when the laser excitation at 458 nm was selected for the Ag-485 substrate. Our study gives a deep insight into LSPR-dependent SERS performance. It also gives a method for giving large SERS enhancement just by selecting a proper excitation wavelength matched to the LSPR of the substrate.

A novel open-tubular capillary electrochromatography with magnetic nanoparticle coating as stationary phase.

A novel open-tubular capillary electrochromatography (OT-CEC) with modified core/shell magnetic nanoparticles coating as stationary phase was introduced using external magnetic force to fix magnetic nanoparticles. The magnetic nanoparticles coating inside the capillary columns could be easily regenerated by removing and re-applying the external magnetic field. Magnetic field intensity, concentration and flow rate of nanoparticles suspension were investigated to achieve simple and stable preparation. Mixture of five organic acids was used as the marker sample to evaluate the OT-CEC system, and the relative column efficiency of anthranilic acid reaches 220,000 plates/m. The excellent within-column and between-column repeatability has been testified with the RSDs of retention time of less than 1.51 and 5.29%, respectively. The aqueous extract of rhizoma gastrodiae was analyzed by the OT-CEC system, and 23 peaks were eluted in 30 min. Compared with conventional open-tubular capillary column, this new system shows faster separation speed and higher column efficiency from the larger surface area of nanoparticles. It has great potential in the method development for the analysis of complex samples, since magnetic coating can effectively prolong the column life by expediently replacing stationary phase to eliminate the pollution or irreversible adsorption.

Cu-coupled Fe/Fe3C covered with thin carbon as stable win-win catalysts to boost electro-Fenton reaction for brewing leachate treatment.

The electro-Fenton oxidation is one of the powerful approaches for achieving the complete mineralization of organic pollutants in water. The key dilemma for efficient industrial application of electro-Fenton oxidation is the complicated post-processing of iron sludge, and the cost and risk associated with H2O2 transportation and storage. Herein, Cu-coupled Fe/Fe3C covered with carbon layer on carbon felt (Cu-Fe/Fe3C@C), engineered by a hydrothermal reaction followed by the consequent thermal-treatment in N2 atmosphere, as a self-supported integrated cathode were used for an onsite oxygen reduction reaction and a Fenton oxidation reaction. Experimental evidences demonstrate that, at the operating potential of -1.1 V, Fe3C can selectively catalyze O2 into H2O2 by 2e reduction pathways with assistance of metal Cu. Meanwhile, metal Fe and Cu incorporated into Cu-Fe/Fe3C@C simultaneously motivate the onsite Fenton oxidation arose by H2O2. Such a win-win catalyst presented high activity in the electro-Fenton process. In acidic environment, the efficient mineralization rate of methylene blue, nitrobenzene, phenol, and bisphenol A can reach more than 70% in 60 min, as well as the excellent stability and durability due to the protection of graphited carbon layer. Compared with tradition electrochemical degrade system, the prepared Cu-Fe/Fe3C@C electrode as cathode for practical refractory brewing leachate treatment reveal more efficient decolorization and mineralization, saving 14.3% of electricity.

Controlled Atmosphere Corrosion Engineering toward Inhomogeneous NiFe-LDH for Energetic Oxygen Evolution.

The "Fe effect" can maximize the activity of nickel-iron layered double hydroxides (NiFe-LDH) toward oxygen evolution reaction (OER) when the iron content, the lattice distortion, the conductivity, and other related factors are well balanced. It is difficult for the homogeneous NiFe-LDH to take good care of the above requirements at the same time. Herein, we proposed an elaborate atmosphere corrosion strategy to construct porous NiFe-LDH with rich edge/surface-Fe defects on Ni foam (NF). Such edge/surface-Fe defects, mainly caused by the local unequal-stoichiometric ratio of Fe/Ni in the nanometer or subnanometer region, are determined by the unbalanced permeating of the acid vapor and the confined reaction of local Fe and Ni species ionized by the acid vapor. Benefiting from the abundant and fantastic edge/surface-Fe defects, the optimal NiFe-LDH prepared by atmosphere corrosion is more energetic for OER than that synthesized in conventional liquid phase, only a potential of 1.481 and 1.552 VRHE to respectively achieve the current density of 100 and 1000 mA cm-2 as well as a satisfactory stability and reproducibility. An overall water-splitting system assembled by inhomogeneous NiFe-LDH and commercial Pt-C can reach a current density of 100 mA cm-2 at a solar cell of 1.72 V. Additionally, the atmosphere corrosion is very suitable for the large-scale, green, and economic synthesis of metal-based catalysts with high enrichment of defects, highlighting its potential for device and industrial applications.

In situ growth of TiO2 in interlayers of expanded graphite for the fabrication of TiO2-graphene with enhanced photocatalytic activity.

We present a facile route for the preparation of TiO(2)-graphene composites by in situ growth of TiO(2) in the interlayer of inexpensive expanded graphite (EG) under solvothermal conditions. A vacuum-assisted technique combined with the use of a surfactant (cetyltrimethylammonium bromide) plays a key role in the fabrication of such composites. Firstly, the vacuum environment promotes full infusion of the initial solution containing Ti(OBu)(4) and the surfactant into the interlayers of EG. Subsequently, numerous TiO(2) nanoparticles uniformly grow in situ in the interlayers with the help of the surfactant, which facilitates the exfoliation of EG under the solvothermal conditions in ethanol, eventually forming TiO(2)-graphene composites. The as-prepared samples have been characterized by Raman and FTIR spectroscopies, SEM, TEM, AFM, and thermogravimetic analysis. It is shown that a large number of TiO(2) nanoparticles homogeneously cover the surface of high-quality graphene sheets. The graphene exhibits a multi-layered structure (5-7 layers). Notably, the TiO(2)-graphene composite (only 30 wt % of which is TiO(2)) synthesized by subsequent thermal treatment at high temperature under nitrogen shows high photocatalytic activity in the degradation of phenol under visible and UV lights in comparison with bare Degussa P25. The enhanced photocatalytic performance is attributed to increased charge separation, improved light absorbance and light absorption width, and high adsorptivity for pollutants.

Synergetic enhancement of surface reactions and charge separation over holey C3N4/TiO2 2D heterojunctions.

Efficient charge separation and rapid interfacial reaction kinetics are crucial factors that determine the efficiency of photocatalytic hydrogen evolution. Herein, a fascinating 2D heterojunction photocatalyst with superior photocatalytic hydrogen evolution performance - holey C3N4 nanosheets nested with TiO2 nanocrystals (denoted as HCN/TiO2) - is designed and fabricated via an in situ exfoliation and conversion strategy. The HCN/TiO2 is found to exhibit an ultrathin 2D heteroarchitecture with intimate interfacial contact, highly porous structures and ultrasmall TiO2 nanocrystals, leading to drastically improved charge carrier separation, maximized active sites and the promotion of mass transport for photocatalysis. Consequently, the HCN/TiO2 delivers an impressive hydrogen production rate of 282.3 µmol h-1 per 10 mg under AM 1.5 illumination and an apparent quantum efficiency of 13.4% at a wavelength of 420 nm due to the synergetic enhancement of surface reactions and charge separation. The present work provides a promising strategy for developing high-performance 2D heterojunctions for clean energy applications.