Ultrasonic neural regulation over two-dimensional graphene analog biomaterials: Enhanced PC12 cell differentiation under diverse ultrasond excitation.

Two-dimensional (2D) biomaterials, with unique planar topology and quantum effect, have been widely recognized as a versatile nanoplatform for bioimaging, drug delivery and tissue engineering. However, during the complex application of nerve repair, in which inflammatory microenvironment control is imperative, the gentle manipulation and trigger of 2D biomaterials with inclusion and diversity is still challenging. Herein, inspired by the emerging clinical progress of ultrasound neuromodulation, we systematically studied ultrasound-excited 2D graphene analogues (graphene, graphene oxide, reduced graphene oxide (rGO) and carbon nitride) to explore their feasibility, accessibility, and adjustability for ultrasound-induced nerve repair in vitro. Quantitative observation of cell differentiation morphology demonstrates that PC12 cells added with rGO show the best compatibility and differentiation performance under the general ultrasound mode (0.5 w/cm2, 2 min/day) compared with graphene, graphene oxide and carbon nitride. Furthermore, the general condition can be improved by using a higher intensity of 0.7 w/cm2, but it cannot go up further. Later, ultrasonic frequency and duty cycle conditions were investigated to demonstrate the unique and remarkable inclusion and diversity of ultrasound over conventional electrical and surgical means. The pulse waveform with power of 1 MHz and duty cycle of 50 % may be even better, while the 3 MHz and 100 % duty cycle may not work. Overall, various graphene analog materials can be regarded as biosafe and accessible in both fundamental research and clinical ultrasound therapy, even for radiologists without material backgrounds. The enormous potential of diverse and personalized 2D biomaterials-based therapies can be expected to provide a new mode of ultrasound neuromodulation.

Construction of an La-BiVO4/O-Doped g-C3N4 Heterojunction Photocatalyst Embedded in Electrospinning Nanofibers.

BiVO4 has been widely used in the field of photocatalysis due to its nontoxic and moderate band gap. However, single BiVO4 has the disadvantages of a high recombination rate of photogenerated carriers and weak response to visible light, inhibiting its photocatalytic applications. To explore viable solutions, a hybrid material composed of lanthanum-doped bismuth vanadate (La-BiVO4) and oxygen-doped porous graphite carbon nitride (O-doped g-C3N4), i.e., La-BiVO4/O-doped g-C3N4 powder, was prepared by a facile hydrothermal reaction and low-temperature calcination. Then, the powder was loaded on polyacrylonitrile nanofibers (NFs) through the electrospinning fiber technique. Various surface science characterizations, including transmission electron microscopy and nitrogen absorption and desorption analysis, confirmed the successful synthesis of a mesoporous heterojunction material. The La3+-doping as well as the porous morphologies and larger specific surface area of the O-doped g-C3N4 ultimately improve the photocatalytic abilities via a proposed Z-scheme heterojunction mechanism. The roles of La3+-doping and morphology modification in promoting the separation of the photogenerated carriers and broadening the optical absorption range were experimentally discussed. The RhB degradation experiment indicated that the La-BiVO4/O-doped g-C3N4 powder has excellent photocatalytic activity, which is about 2.85 and 2 times higher than that of the pure BiVO4 and O-doped g-C3N4, respectively. Meanwhile, the La-BiVO4/O-doped g-C3N4 NF shows good stability and recoverability after a 10-cycle testing. Such a hybrid photocatalyst with a proposed Z-scheme heterojunction mechanism and good plasticity might pave a feasible way to fabricate a new library of photocatalysts.

Emerging high-ammonia­nitrogen wastewater remediation by biological treatment and photocatalysis techniques.

The bacterial and photocatalysis techniques have been widely applied into the remediation of ammonia nitrogen wastewater. Although traditional microbial methods had been verified useful; more efficient, energy-saving and controllable candidate treatment methods are still urgently needed to cover the increasingly diverse ammonia nitrogen pollution cases. The bacterial treatment technique for ammonia nitrogen mainly depends on the ammonia nitrogen oxidation-reduction (e.g. nitrification, denitrification) by nitrifying bacteria and denitrifying bacteria, but these reactions suffer from slow denitrifying kinetic process and uncontrolled disproportionation reaction. In comparison, the photocatalysis technique based on photoelectrons is more efficient and has some advantages, such as low temperature reaction and long life, while the photocatalysis technique can not perform multiple complex biochemical reactions. Despite much scientific knowledge obtained about this issue recently, such research has yet not been widely adopted in the industry because of many concerns about subsequent catalyst stability and economic feasibility. This review summarized and discussed the very recent achievements and key problems on remediation of high-ammonia­nitrogen wastewater and oxidation driven by bacterial treatment and photocatalysis techniques, as well as the most promising future directions for these two techniques, especially the potential of jointly bacterial-photocatalysis techniques.

Ultrafast plasma method allows rapid immobilization of monatomic copper on carboxyl-deficient g-C3N4 for efficient photocatalytic hydrogen production.

Transition-metal monometallic photocatalysts have received extensive attention owing to the maximization of atomic utilization efficiency. However, in previous related works, single-atom loading and stability are generally low due to limited anchor sites and mechanisms. Recently, adding transition-metal monatomic sites to defective carbon nitrides has a good prospect, but there is still lack of diversity in defect structures and preparation techniques. Here, a strategy for preparing defect-type carbon-nitride-coupled monatomic copper catalysts by an ultrafast plasma method is reported. In this method, oxalic acid and commercial copper salt are used as a carboxyl defect additive and a copper source, respectively. Carbon nitride samples containing carboxyl defects and monatomic copper can be processed within 10 min by one-step argon plasma treatment. Infrared spectroscopy and nuclear magnetic resonance prove the existence of carboxyl defects. Spherical aberration electron microscopy and synchrotron radiation analysis confirm the existence of monatomic copper. The proportion of monatomic copper is relatively high, and the purity is high and very uniform. The Cu PCN as-prepared shows not only high photo-Fenton pollutant degradation ability but also high photocatalytic hydrogen evolution ability under visible light. In the photocatalytic reaction, the reversible change of Cu+/Cu2+ greatly promotes the separation and transmission of photogenerated carriers and improves the utilization of photoelectrons. The photocatalytic hydrogen evolution rate of the optimized sample is 8.34 mmol g-1·h-1, which is 4.54 times that of the raw carbon nitride photocatalyst. The cyclic photo-Fenton experiment confirms the catalyst has excellent repeatability in a strong oxidation environment. The synergistic mechanism of the photocatalyst obtained by this plasma is the coordination of single-atom copper sites and carboxyl defect sites. The single copper atoms incorporated can act as an electron-rich active center, enhancing the h+ adsorption and reduction capacity of Cu PCN. At the same time, the carboxyl defect sites can form hydrogen bonds to stabilize the production of hydrogen atoms and subsequently convert them to hydrogen because of the unstable hydrogen bond structure. This plasma strategy is green, convenient, environment-friendly, and waste-free. More importantly, it has the potential for large-scale production, which brings a new way for the general preparation of high-quality monatomic catalysts.

H2+CO2 Synergistic Plasma Positioning Carboxyl Defects in g-C3N4 with Engineered Electronic Structure and Active Sites for Efficient Photocatalytic H2 Evolution.

Defective functional-group-endowed polymer semiconductors, which have unique photoelectric properties and rapid carrier separation properties, are an emerging type of high-performance photocatalyst for various energy and environmental applications. However, traditional oxidation etching chemical methods struggle to introduce defects or produce special functional group structures gently and controllably, which limits the implementation and application of the defective functional group modification strategy. Here, with the surface carboxyl modification of graphitic carbon nitride (g-C3N4) photocatalyst as an example, we show for the first time the feasibility and precise modification potential of the non-thermal plasma method. In this method, the microwave plasma technique is employed to generate highly active plasma in a combined H2+CO2 gas environment. The plasma treatment allows for scalable production of high-quality defective carboxyl group-endowed g-C3N4 nanosheets with mesopores. The rapid H2+CO2 plasma immersion treatment can precisely tune the electronic and band structures of g-C3N4 nanosheets within 10 min. This conjoint approach also promotes charge-carrier separation and accelerates the photocatalyst-catalyzed H2 evolution rate from 1.68 mmol h-1g-1 (raw g-C3N4) to 8.53 mmol h-1g-1 (H2+CO2-pCN) under Xenon lamp irradiation. The apparent quantum yield (AQY) of the H2+CO2-pCN with the presence of 5 wt.% Pt cocatalyst is 4.14% at 450 nm. Combined with density functional theory calculations, we illustrate that the synergistic N vacancy generation and carboxyl species grafting modifies raw g-C3N4 materials by introducing ideal defective carboxyl groups into the framework of heptazine ring g-C3N4, leading to significantly optimized electronic structure and active sites for efficient photocatalytic H2 evolution. The 5.08-times enhancement in the photocatalytic H2 evolution over the as-developed catalysts reveal the potential and maneuverability of the non-thermal plasma method in positioning carboxyl defects and mesoporous morphology. This work presents new understanding about the defect engineering mechanism in g-C3N4 semiconductors, and thus paves the way for rational design of effective polymeric photocatalysts through advanced defective functional group engineering techniques evolving CO2 as the industrial carrier gas.

N, P Codoped Hollow Carbon Nanospheres Decorated with MoSe2 Ultrathin Nanosheets for Efficient Potassium-Ion Storage.

Potassium-ion batteries (KIBs) are gradually being considered as an alternative for lithium-ion batteries because of their non-negligible advantages such as abundance and low expenditure of K, as well as higher electrochemical potential than another alternative─sodium-ion batteries. Nevertheless, when the electrode materials are inserted and extracted with large-sized K+ ions, the tremendous volume change will cause the collapse of the microstructures of electrodes and make the charging/discharging process irreversible, thus disapproving their extended application. In response to this, we put forward a feasible strategy to realize the in situ assembly of layered MoSe2 nanosheets onto N, P codoped hollow carbon nanospheres (MoSe2/NP-HCNSs) through thermal annealing and heteroatom doping strategies, and the resulting nanoengineered material can function well as an anode for KIBs. This cleverly designed nanostructure of MoSe2/NP-HCNS can broaden the interlayer spacing of MoSe2 to boost the efficiency of the insertion/extraction of K ions and also can accommodate large volume change-caused mechanical strain, facilitate electrolyte penetration, and prevent the aggregation of MoSe2 nanosheets. This synthetic method generates abundant defects to increase the amounts of active sites, as well as conductivity. The hierarchical nanostructure can effectively increase the proportion of pseudo-capacitance and promote interfacial electronic transfer and K+ diffusion, thus imparting great electrochemical performance. The MoSe2/NP-HCNS anode exhibits a high reversible capacity of 239.9 mA h g-1 at 0.1 A g-1 after 200 cycles and an ultralong cycling life of 161.1 mA h g-1 at 1 A g-1 for a long period of 1000 cycles. This nanoengineering method opens up new insights into the development of promising anode materials for KIBs.

Mesoporous structure and amorphous Fe-N sites regulation in Fe-g-C3N4 for boosted visible-light-driven photo-Fenton reaction.

Heterogeneous photo-Fenton catalysts prepared by doping metal ions in g-C3N4 are promising alternatives to traditional homogeneous Fenton catalysts, but are restricted by poor mesoporous structure and agglomerate of metal species. Recently, the highly uniformly dispersed metal-N active sites in various photocatalysts have been proved to be the critical reason for their enhanced catalytic activity. In this study based on reasonable control of mesoporous structure and metal-N active sites, mesoporous Fe-g-C3N4 was synthesized using a simple one-step thermal shrinkage polymerization method using ferrous oxalate as iron source and pore-forming agent. The Fe and N elements in the triazine ring skeleton of Fe-g-C3N4 form a σ-π bond, thus the photogenerated electrons can be quickly transferred to Fe3+ to form Fe2+ under the interaction of chemical bonds, accelerating the Fenton reaction rate. Density functional theory calculations results demonstrate that the energy band structure and electron cloud density distribution of Fe-Nx active structure are better than that of routine FeOx crystal structure with metal species agglomeration. In addition, the excellent mesoporous structure of Fe-g-C3N4 creates conditions for the high exposure of Fe-Nx active sites in the photo-Fenton reaction under visible light. The as-developed Fe-g-C3N4 system shows high recyclability and excellent photo-Fenton performance for removal of typical intractable pollutants (The degradation rate of dye and tetracycline reaches 98.2% and 98.7% at 60 and 120 min, respectively). This work provides a facile and sustainable route to develop mesoporous highly-active heterogeneous Fenton-like catalysts and even further general the design of general catalyst with ideal metal-N active sites, thereby promoting a feasible and efficient wastewater remediation solution.

Boosting potassium-ion storage in large-diameter carbon nanotubes/MoP hybrid.

Potassium-ion batteries (KIBs) as a substitute for lithium ion batteries have attracted tremendous attention in recent years thanks to the cost-effectiveness and abundance of potassium resources. However, the current lack of suitable electrode materials is a major obstacle against the practical application of KIBs. Hence, design and preparation of capable anode materials are critical for the development of KIBs. In this study, a promising electrode based on N, P-codoped large diameter hollow carbon nanotubes decorated with ultrasmall MoP nanoparticles (MoP@NP-HCNTs) were prepared. The hollow carbon nanotubes facilitate the rapid electron and ion transfer, and release the huge volume expansion during discharge/charge. The MoP@NP-HCNT electrode delivers high initial capacity of 485, 482 and 463 mAh g-1 corresponding to 100, 200 and 1000 mA g-1, respectively. The discharge specific capacity still maintains 300 mAh g-1 at 100 mA g-1 after over 80 cycles. It still shows ultralong cycling stability with a discharge capacity of 255 mAh g-1 at a high current density of 1000 mA g-1 after 120 cycles. This study opens up a new routine to develop high reversible capacity and promising electrode materials for KIBs.

Co-Immobilization of Ce6 Sono/Photosensitizer and Protonated Graphitic Carbon Nitride on PCL/Gelation Fibrous Scaffolds for Combined Sono-Photodynamic Cancer Therapy.

Aiming at developing a moderate and efficient sono-photodynamic therapy for breast cancer, tissue engineering scaffolds may provide an easy and efficient strategy to eliminate serious side effects in conventional surgery or chemotherapy, and thus, they are highly desired. However, the development of ideal sono-photodynamic therapeutic scaffolds is always hindered by the poor stability and incompatibility between the different biomaterial components. Herein, the Food and Drug Administration (FDA)-approved sono/photosensitizer Chlorin e6 (Ce6) was successfully and tightly incorporated into electrospun polycaprolactone/gelatin (PG) scaffolds via positively charged protonated g-C3N4 nanosheets (pCN). The PG fibers were precoated with graphene oxide (GO) to enable the assembly of pCN on the surface through electrostatic interactions. The Ce6@pCN-GO-PG composite scaffolds exhibited good cytocompatibility and excellent sono-photodynamic activity, leading to distinctly boosted reactive oxygen species (ROS) generation and a 95.8% inactivation rate of breast cancer cells through a synergistic sono-photodynamic process triggered by an 808 nm laser and 1 MHz ultrasound (US) excitation, within the clinical therapeutic dose. The as-developed scaffolds with unique ultrasound cavitation therapeutic effects can be used not only for complete eradication of tumor cells after surgery but also as a cell behavior observation platform of sono-photodynamic cancer therapy.

Synthesis of three-dimensional Sn@Ti3C2 by layer-by-layer self-assembly for high-performance lithium-ion storage.

Powerful yet orderly nanostructure lithium-ion batteries (LIBs) are eagerly desired to satisfy the practical application of portable electronics and smart grids. However, the surface re-stacking and surface functionalization on the MXenes in the anode electrode severely restrict the accessibility to electrolyte ions, hindering the full utilization of their intrinsic properties. To address this challenge, we rationally design three-dimensional (3D) Sn@Ti3C2 materials and fabricate them in a unique layer-by-layer manner through self-assembly for boosting LIBs. In this design system for fast lithium-ion storage, the Ti3C2 MXene nanosheets serving as 3D scaffolds buffer the severe volume expansion and agglomeration of Sn nanoparticles (NPs) and enhance electrode conductivity at the interface. Furthermore, Sn NPs are embedded as interlayer spacers to prevent nanosheet re-stacking and provide outstanding electrochemical performance. The nanostructure can increase the lithium-ion diffusion coefficient and create additional active sites. As a result, the Sn@Ti3C2 anode exhibits a superior specific capacity up to 666 mA∙h∙g-1 at 0.5 A∙g-1 after 250 cycles. Compared with pure Sn NPs, the improved electrochemical performance of Sn@Ti3C2 can be ascribed to the high electronic conductivity of Ti3C2 MXene nanosheets. The 3D Sn@Ti3C2 materials prepared in a layer-by-layer manner through self-assembly display promising performances for LIBs.

Ultrasound and Near-Infrared Light Dual-Triggered Upconversion Zeolite-Based Nanocomposite for Hyperthermia-Enhanced Multimodal Melanoma Therapy via a Precise Apoptotic Mechanism.

High reactive oxygen species (ROS) generation efficiency and induction of targeted cell apoptosis are recognized as key objectives to achieve a highly efficient strategy for cancer therapy with minimum side effects of inflammatory reactions. However, it is still a challenge to realize higher therapeutic efficiency with a cell apoptosis model. Herein, we present strong upconversion luminescent biosafe cores derived from Linde Type A (LTA) zeolites and modification with targeted/therapeutic drugs for multimodal therapy, in which sonodynamic therapy (SDT) combined with photodynamic therapy (PDT) increases therapeutic efficiency especially in deep sites of tumor via producing cytoplasmic ROS and mitochondrial superoxide and photothermal therapy (PTT) enhances PDT effects via higher fluorescence resonance energy transfer (FRET) efficacy attributed to an increased temperature. Furthermore, the transcriptomic analysis reveals that cellular internalization of the nanosystem can lead to tumor ablation via cell apoptosis. We expect that the multimodal therapy based on LTA zeolite drug nanocarriers could be applied in the cancer therapeutics in the near future.

Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra.

A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb2+) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb2+ due to the aggregation-induced emission enhancement (AIEE) between Pb2+ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb2+. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs-CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb2+ in the range of 0.010-2.5 mg L-1, with a detection limit of 0.0031 mg L-1. Finally, the probe was successfully applied to detect Pb2+ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb2+ in porphyra.

An instant, biocompatible and biodegradable high-performance graphitic carbon nitride.

Polymer graphitic carbon nitride (g-C3N4) materials have attracted growing interest owing to their impressive applicability in photocatalysis and optoelectronic devices. However, further applications of g-C3N4 materials are greatly restricted by their chemical inertness and insolubility in most solvents. Regarding the rising prospect of g-C3N4 nanosheets in the biomedicalfield, high solubility and biocompatibility are required for the further development of g-C3N4 materials. In this study, a simple one-step thermal polymerization method was designed to prepare fast-soluble mesoporous g-C3N4 nanosheets by using NH4HSO4 as the critical adjuvant. The products, especially the optimal g-C3N4 NSs-4, showed impressive solubility, biocompatibility and partial biodegradability. The enriched surface hydrophilic groups (-NH2 and -OH) may contribute to improving the solubility of g-C3N4 nanosheets, while the partial biodegradability can be ascribed to the presence of the disulfide bond in the g-C3N4 framework. In this system, the NH4HSO4 adjuvant acted not only as O and S sources, but also as a bubbling agent that endows the g-C3N4 a porous structure with greatly enlarged specific surface area and high separation efficiency of photogenerated electron-hole pairs. These integrative positive factors also greatly contributed to the photocatalytic activity of the g-C3N4 nanosheets. This facile, economic and general fabrication strategy for mesoporous, fast-soluble and biocompatible g-C3N4 with superior visible-light photocatalytic activity is promising in environmental, energy and biomedical fields.

Facile synthesis of 3D flower-like mesoporous Ce-ZnO at room temperature for the sunlight-driven photocatalytic degradations of RhB and phenol.

A 3D flower-like mesoporous Ce doped ZnO composite composed of nanosheets was prepared by a facile, one-step wet chemical method at room temperature. It was found that the moderate Ce doping can improve the light absorption of ZnO. The photocatalytic activities of the samples were studied by the degradation of Rhodamine B (RhB) and phenol under stimulated sunlight. The 1% mole ratio of Ce doped ZnO composites (denoted as CZ1) showed higher photocatalytic performance than other samples, where 85.1% of RhB and 69.6% of phenol can be removed within 125 min and 120 min, respectively. The Ce4+ doped in the lattice of ZnO can act as the electron trapping sites, which effectively improve the electron-hole separation. In addition, it was also found the annealing temperature had effect on the morphology and structure of Ce doped ZnO. The photocatalytic performance can be further enhanced at proper annealing temperature (500 °C) due to the increase of ZnO crystallinity with maintained flower-like structure and the formation of CeO2-ZnO heterojunction at their tight interface promoting the separation of photogenerated electron-hole pairs.

Polymeric structure optimization of g-C3N4 by using confined argon-assisted highly-ionized ammonia plasma for improved photocatalytic activity.

The optimization of the polymeric structure and the modulation of surface amino groups in graphitic carbon nitride (g-CN) are critical but challenging in improving the photoelectric and photocatalytic performances of this polymer semiconductor. Ammonia plasma treatment may provide a fast and useful approach to optimize g-CN materials yet is seriously restricted by the low ionization ability of ammonia. Herein, a confined fast and environmental-friendly ammonia plasma method based on argon-assisted high ionization of NH3 was developed for efficient modification of raw g-CN. Compared with the weakly-ionized pure ammonia plasma which can only introduce amino group onto the surface g-CN, the argon-assisted highly-ionized ammonia plasma treatment obviously contributes to the comprehensively polymeric structure optimization of g-CN, and thus plays a key role in enhancing its light-harvesting and decelerating the recombination of the photogenerated charge carriers. As a result, the argon-assisted highly-ionized ammonia plasma-treated g-CN-Ar+NH3 outperformed the raw g-CN by a 2.5-fold higher photocatalytic reduction of hexavalent chromium and a remarkable 3.8-fold higher photocatalytic H2 evolution activity (up to 957.8 µmol·h-1·g-1) under visible light irradiation. Our findings suggest the great prospects of this novel highly-ionized ammonia plasma treatment method in the controllable modification of semiconductors and polymers.

Three-dimensional mesoporous sandwich-like g-C3N4-interconnected CuCo2O4 nanowires arrays as ultrastable anode for fast lithium storage.

Inspite of their impressive high theoretical capacity as Lithium-ion batteries (LIBs) anodes, spinel transition-metal oxides (TMOs) suffer serious volume expansion, aggregation and the pulverization of crystal structures during lithiation/delithiation, and this process severely restrict their industrial application. Multi-dimensional morphological engineering of spinel TMO nanostructures is an effective way to solve this issue. In this work, using facile hydrothermal synthetic methods, spinel CuCo2O4 nanowires arrays are synthesized and supported on g-C3N4 nanosheets, thus forming a unique sandwich-like interconnected three-dimensional mesoporous structure containing high amount of void spaces. Addition of g-C3N4 nanosheets to CuCo2O4 nanowire arrays may shorten the Li+ diffusion distance and electron transfer pathway, and may also provide more active sites for Li+ diffusion into electrolyte and buffer for the volume expansion and aggregation of CuCo2O4. As a LIB anode material, CuCo2O4@g-C3N4 shows initial lithiation capacity of 840.6 mAh g-1, and capacity retention of 641.2 mAh g-1 after 60 cycles at the current density of 0.1 A g-1 and 499.2 mAh g-1 after 40 cycles at high current of 1 A g-1, which is significantly better than value of pure CuCo2O4 nanowires. This work affords a new way to tackle the problem of volume expansion of high capacity spinel TMO anode materials using g-C3N4 nanosheets as buffering agent.

Oxygen vacancy-rich nitrogen-doped Co3O4 nanosheets as an efficient water-resistant catalyst for low temperature CO oxidation.

Over the past decade, there has been significant research of Co3O4 catalysts for oxidation of carbon mono-oxide (CO) at low temperatures. However, development of water-resistant Co3O4 materials is still challenging. In this work, a novel oxygen vacancy-rich nitrogen-doped Co3O4 catalyst was developed using straightforward urea-assisted method. Nitrogen doping increases oxygen vacancies on the surface in Co3O4 as well as improves the activity of lattice oxygen. Comparing with pure Co3O4 and Co3O4 with less nitrogen doping, the as-synthesized nitrogen-doped Co3O4 exhibited significantly enhanced activity as well as water resistance in the catalytic oxidation of CO. To the best of our knowledge, this is the first example of CO oxidation on N-doped Co3O4, which provides a new strategy for developing highly active and water-resistant catalysts.

Surface Amino Group Regulation and Structural Engineering of Graphitic Carbon Nitride with Enhanced Photocatalytic Activity by Ultrafast Ammonia Plasma Immersion Modification.

Surface amino group regulation and structural engineering of graphitic carbon nitride (g-CN) for better catalytic activity have increasingly become a focus of academia and industry. In this work, the ammonia plasma produced by a microwave surface wave plasma generator was developed as a facile source to achieve fast, controllable surface modification, and structural engineering of g-CN by ultrafast plasma treatment in minutes, thus enhancing photocatalytic performance of g-CN. The morphology, surface hydrophilicity, optical absorption properties, and states of C-N bonds were investigated to determine the effect of plasma immersion modification on the g-CN catalyst. The structure and photoelectric features of the plasma-modified samples were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The results indicate that the ammonia plasma-treated g-CN-NH3 exhibits an ultrathin nanosheet structure, enriched amino groups, and an ideal molecular structure, a narrower band gap (2.35 eV), extended light-harvesting edges (560 nm), and enhanced electron transport ability. The remarkably enhanced photocatalytic activity demonstrated in the photoreduction and detoxification of hexavalent chromium (Cr(VI)) can be ascribed to the optimization of the structural and photoelectric properties induced by the unique ammonia plasma treatment. The effective and ultrafast approach developed in this work is promising in the surface amino group regulation and structural engineering of various functional materials.

Nanocasting synthesis of chromium doped mesoporous CeO2 with enhanced visible-light photocatalytic CO2 reduction performance.

Chromium doped mesoporous CeO2 catalysts were synthesized via a simple nanocasting route by using silica SBA-15 as the template and metal nitrates as precursors. The effect of Cr doping concentration (5%, 10%, 15% and 20% of the initial Cr/(Cr+Ce) molar percentage) on the structures of these catalysts and their photocatalytic performances in reduction of CO2 with H2O were investigated. The results indicated that the introduction of Cr species could effectively extend the spectral response range from UV to visible light region (400-700nm) and improve the electronic conductivity for the mesoporous CeO2 catalysts which exhibited an enhanced photocatalytic activity in the reduction of CO2 with H2O when compared with the non-doped counterpart. The highest CO and CH4 yield of 16.2µmol/g-cat. and 10.1µmol/g-cat., respectively, were acquired on the optimal chromium doped CeO2 catalyst with the initial Cr(Cr+Ce) molar percentage of 15% under 8h visible-light irradiation, which were more than twice as high as that of bare CeO2. The remarkably increased photocatalytic performance should be attributed to the advantageous structural and compositional features of the chromium doped mesoporous CeO2.

Reduced graphene oxide wrap buffering volume expansion of Mn2SnO4 anodes for enhanced stability in lithium-ion batteries.

MSnO4 (M = Mn, Zn, Co, Mg, etc.) has been widely investigated as an anode material for lithium-ion batteries in recent years, but its practical applications are limited by serious capacity loss caused by severe volume expansion during Li+ insertion/extraction. So far, hollow structures, carbon coating, and encapsulation by reduced graphene oxide have been introduced to improve the electrochemical properties of MSnO4. In this study, Mn2SnO4 nanoparticles@reduced graphene oxide (Mn2SnO4@rGO) composites were prepared using simple steps and applied as anode materials for lithium-ion batteries. The rGO sheet encapsulated Mn2SnO4 nanoparticles show improved electrochemical properties. The first discharge capacity of Mn2SnO4@rGO reaches 1223.5 mAh g-1 and remains at 542.0 mAh g-1 after 100 cycles at a current density of 0.1 A g-1. The electrochemical properties were significantly improved compared to those of pure Mn2SnO4 nanoparticles.