Facile Semiconductor p-n Homojunction Nanowires with Strategic p-Type Doping Engineering Combined with Surface Reconstruction for Biosensing Applications

Photosensors with versatile functionalities have emerged as a cornerstone for breakthroughs in the future optoelectronic systems across a wide range of applications.In particular,emerging photoelectrochemical(PEC)-type devices have recently attracted extensive interest in liquid-based biosensing applications due to their natural electrolyte-assisted operating characteristics.Herein,a PEC-type photosensor was carefully designed and constructed by employing gallium nitride(GaN)p-n homojunction semiconductor nanowires on silicon,with the p-GaN segment strategically doped and then decorated with cobalt-nickel oxide(CoNiO_(x)).Essentially,the p-n homojunction configuration with facile p-doping engineering improves carrier separation efficiency and facilitates carrier transfer to the nanowire surface,while CoNiO_(x)decoration further boosts PEC reaction activity and carrier dynamics at the nanowire/electrolyte interface.Consequently,the constructed photosensor achieves a high responsivity of 247.8 mA W^(-1)while simultaneously exhibiting excellent operating stability.Strikingly,based on the remarkable stability and high responsivity of the device,a glucose sensing system was established with a demonstration of glucose level determination in real human serum.This work offers a feasible and universal approach in the pursuit of high-performance bio-related sensing applications via a rational design of PEC devices in the form of nanostructured architecture with strategic doping engineering.

Decorative Wood Fiber/High-Density Polyethylene Composite with Canvas or Polyester Fabric

Wood-plastic composite is an environmentally friendly material,due to its use of recycled thermoplastics and plant fibers.However,its surface lacks attractive aesthetic qualities.In this paper,a method of decorating wood fiber/high-density polyethylene(WF/HDPE)without adding adhesive was explored.Canvas or polyester fabrics were selected as the surface decoration materials.The influence of hot-pressing temperature and WF/HDPE ratio on the adhesion was studied.The surface bonding strength,water resistance,and surface color were evaluated,and observation within the infrared spectrum and under scanning electron microscopy was used to analyze the bonding process.The results showed that the fabric and WF/HDPE substrate could be closely laminated together depending on the HDPE layer accumulated on the WF/HDPE surface.The molten HDPE matrix penetrates canvas more easily than polyester fabric,and the canvasveneered composite shows a greater bonding strength than does the polyester fabric-veneered composite.A higher proportion of the thermoplastic component in the substrate improved the bonding.When the hot-pressing temperature exceeded 160°C,the fabric-veneered WF/HDPE panels had greater water resistance,although the canvas fabric changed more obviously in terms of fiber shape and color,compared with the polyester fabric.For the canvas fabric,140°C–160°C was a suitable hot-pressing temperature,whereas 160°C–180°C was more suitable for polyester fabric.The proportion of the thermoplastic component in the composite should be not less than 30%to achieve adequate bonding strength.

Facile synthesis of C-decorated Fe,N co-doped TiO_2 with enhanced visible-light photocatalytic activity by a novel co-precursor method

Lattice‐doping and surface decoration are prospective routes to improve the visible‐light photocatalytic ability of TiO2,but the two techniques are difficult to combine into one preparation process because they are usually conducted under different conditions,which limits the efficiency of TiO2 modification.In this study,TiO2 was successfully modified by simultaneous lattice‐doping and surface decoration,and the visible‐light photocatalytic capacity was largely improved.Upon comparing the method reported here with previous ones,the most significant difference is that Fe(II)‐phenanthroline was first used as the co‐precursor of the introduced elements of C,N,and Fe.These three elements were simultaneously introduced to TiO2 at high levels by this co‐precursor method.The as‐synthesized photocatalysts were systemically investigated and analyzed by several characterization methods such as XRD,FT‐IR,XPS,Raman spectroscopy,EPR,UV‐Vis DRS,photoluminescence spectra,photocurrent,electrochemical impedance spectra,TEM,and HRTEM.The photocatalytic degradation of 4‐NP under visible‐light irradiation was used to evaluate the photocatalytic activity of the photocatalysts.Based on the experimental data,a probable mechanism for the photocatalytic degradation by the photocatalysts is proposed.This is a novel method of using one source to simultaneously introduce metal and non‐metal elements to TiO2 at high levels,which may provide a new way to prepare highly effective TiO2 photocatalysts.

Influence of Rinse on Self-Activated Luminescence in ZnS Nanocrystallite

The self-activated (SA) luminescence in ZnS nanoparticles was studied by comparing the UV-light irradiation induced spectral change, Raman spectra, and EPR spectra of the un-rinsed and rinsed samples. The results show that the SA centers prefer to occupy the sites near the surface and that the donor of SA emission may be related to organic functional groups such as -OH, -CH 3, and -COO. The EPR signals are enhanced remarkably in the rinsed nanoparticles comparing with that in the un-rinsed ones. It is believed that organic functional groups physically combine with the surface dangling bonds of ZnS nanoparticles, leading the nonradiative transition channels to decrease, and thus the SA emission to increase.

High-yield Synthesis of Nanohybrid Shish-kebab Polyethylene-carbon Nanotube Structure

We report a novel method to prepare nanohybnd shish-kebab （NHSK） structure of polyethylene （PE）and carbon nanotube （CNT）. Pristine CNTs without surface modification with high concentration was effectively dispersed in xylene solution by a simple shearing method, which induces the quick crystallization of PE in xylene to form a novel NHSK structure with more dense and smaller PE kebab on CNT axis. The flocculated NHSK productwas transferred quickly from the xylene solution to the ethanol solution, in order to shorten the preparation time. The freeze-drying method was used in vacuum instead of high-temperature drying to avoid the aggregation of NHSK product. These improvements allow the formation of NHSK with an absolute yield of 200 mg.h-1, which is 2000 folds of that reported previously. It is favorable to apply this structured material in high performance nano- composite, by improving the compatibility of CNTs in p polymer and the interfacial force between CNTs and polymer.

The ancient Chinese casting techniques

In the course of Chinese civilization,which lasted more than 5,000 years,casting production has made a huge contribution.In this paper,some representative metal castings were presented.According to their forming techniques,they can be grouped into stone mould casting,clay mould casting,ablation casting,lost wax casting,stack casting,permanent mould casting,sand casting,etc.According to their materials,they can be categorized into tin bronze,bimetallic bronze,malleable cast iron,ductile cast iron,brass,cupronickel alloy (Packtong),etc.According to their surface decorative techniques they can be devided into gem inlay,gilding,gold and silver inlay,copper inlay,engraved decoration,surface tin-enrichment,mother-of-pearl inlay,burnished works with gold or silver inlay,surface coloring and cloisonné enamel,etc.

Surface decoration of mesocarbon microbeads with multifunctional TiNbO_(4-x)@C coating layer as high rate and stable anode of Li-ion batteries

Surface modification of graphite anode with electroactive matters has been proven of a more practical strategy in enhancing the performance of Li-ion batteries than exploring alternative novel anode materials.Herein,rutile TiNbO_(4-x) nanoparticles with a tunnel structure are employed as multifunctional decoration substances in combination with a carbon coating layer to improve the rate and cycle properties of mesocarbon microbeads(MCMBs).As compared to pristine MCMB,the Li^(+)diffusion coefficients of the composite anodes are enhanced due to the synergistic effect of TiNbO_(4-x)@C.Meanwhile,the overcharge and voltage polarization of the composite anodes at high rate are obviously minimized due to the current sharing effect of the high-potential TiNbO_(4-x).Moreover,the amorphous Li_(y)TiNbO_(4-x) converted from TiNbO_(4-x) in the initial lithiation process can deliver pseudocapacitive capacity to the composite anodes from the second cycle.All of these functions of TiNbO_(4-x)@Ccoating layer have directly contributed to the improved rate and cycle performance of the MCMB/TiNbO_(4-x)@C composite anodes.The one containing 12.0 wt%TiNbO_(4-x) exhibits a high reversible specific capacity of 118 m Ah·g^(-1)at 10C(1C=372 m A·g^(-1)),together with a high capacity retention of 90.9%after 300 cycles at 3C,which are all much superior to those of pristine MCMB.

The exclusive surface and electronic effects of Ni on promoting the activity of Pt towards alkaline hydrogen oxidation

Ni modification is considered as an efficient strategy for boosting the performance of Pt towards alkaline hydrogen oxidation reaction(HOR),yet its specific role is largely undecoded.Here,ultrathin Pt nanowires(NWs)are selected as models for revealing the significance of Ni modification on HOR by precisely positioning Ni on distinct positions of Pt NWs.Ni solely influences the electronic properties of Pt and thus weakens*H adsorption when it is located in the core of PtNi alloyed NWs,leading to a moderate improvement of alkaline HOR activity.When Ni is distributed in both core and surface of PtNi alloyed NWs,Ni strongly weakens*H adsorption but strengthens*OH adsorption.On the other hand,the electronic properties of Pt are hardly influenced when Ni is deposited on the surface of Pt NWs,on which the strong*H and*OH adsorptions lead to the improved HOR activity.This work reveals the significance of Ni modification on HOR,but also promotes the fundamental researches on catalyst design for fuel cell reactions and beyond.

Synergistic Optimization of Toughness and EMI Shielding Properties in Rigid Polyurethane Composites by Designing Ring Structures on the Surface of Carbon Fibers

How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness(EMI SE)of carbon fibers(CFs)reinforced rigid polyurethane(RPU)composites is a significative challenge at present.In this work,a ring-shaped zinc coating was deposited on the short CFs by electrodeposition technique.It is expected to improve the interfacial properties between the fibers and the resin matrix as well as enhance the EMI shielding properties of the composites by changing the surface morphology and roughness of the fibers.Results showed that the surface free energy of the ring-shaped zinc modified carbon fibers(RS-CFs)increased from 49.0 mJ/m^(2) to 53.2 mJ/m^(2),indicating that the surface roughness and wettability of the CFs were effectively improved.In comparison with the pristine short carbon fibers/rigid polyurethane(CFs/RPU)composites,tensile strength and tensile toughness of RS-CFs modified composites were increased by 27.1% and 121.4%,respectively.In addition,the bending and impact strengths of RS-CFs reinforced RPU composites were also improved.Notably,the electrical conductivity of RS-CFs/RPU composites reached 1.2×10^(-5) S/m,which was much higher than that of CFs/RPU composites at 1.4×10^(-10) S/m.Moreover,the EMI SE of the modified composites reached 22 dB,which was 152.9% higher than that of CFs/RPU composites.The enhanced electrical conductivity and EMI shielding properties of the composites could be attributed to the synergistic effect of the porous structure in the RPU matrix and the CFs modified by the metal coating.

Harnessing bacteria for tumor therapy:Current advances and challenges

After a century of standstill,bacteria-based tumor therapy has resurged recently benefiting from the revolution of tumor immunotherapy,which provides unique solutions to tackle the obstacles of traditional tumor treatments.Obligate and facultative anaerobes with active tropism can selectively colonize at tumor sites and suppress tumor growth via different mechanisms,serving as attractive tools for tumor treatment either as a monotherapy or combining with other therapies for synergistic anti-tumor effects.In this critical review,we introduce the recent advances of bacteria-based tumor therapy from the following aspects.First,the general properties of bacteria are reviewed emphasizing on their structural components related to tumor immunotherapy,and the main bacteria that have been used in tumor therapy are listed.Then,the benefits of bacteria for tumor therapy are illustrated,such as tumor targetability,deep penetration,and facile genetic engineering for attenuation,enhanced efficacy,as well as bioimaging.Next,anti-tumor mechanisms of bacteria are summarized,which refer to intrinsic tumoricidal activities,immune activation,bacteria metabolism,and their capability to regulate gut microbiota homeostasis.Moreover,bacteria could act as carriers to deliver various types of therapeutics to achieve combination therapy with improved efficacy.In addition,several challenges for anti-tumor applications of bacteria are discussed regarding the delivery,efficacy and safety issues,and potential solutions are also provided.Finally,the possible improvements and perspectives are discussed in the end,which provide a guideline for the design of advanced bacteria-based tumor therapeutics in the future.

Surface decoration prompting the decontamination of active sites in high-temperature proton exchange membrane fuel cells

In electrochemical energy devices,the operating conditions always exert enormous influence on electrocatalysts'performances.Phosphoric acid(PA),acted as the proton carriers,can be adsorbed on Pt surface,block active sites and affect the electronic structure of Pt unfavorably,which severely restricts the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFCs).Herein,simply basic organic compounds,such as dicyandiamide(DCD),melamine(Mel)and cyanuric acid(CA),are decorated on Pt surface(DCD-Pt/C,Mel-Pt/C and CA-Pt/C)to induce the adsorption transfer of proton carriers.The decoration can not only inject electrons to Pt and enhance oxygen reduction reaction(ORR)activity but also can induce PA to transfer from Pt surface to organic compounds,decontaminating active sites.In addition,the organic compounds with the larger conjugated system and the smaller electronegativity of ligating atoms would have a greater interaction with Pt,causing a larger decoration amount on Pt surface,which leads to more excellent ORR activity and resistance to PA blockage effect.Therefore,MelPt/C shows a peak power density of 629 mW/cm^(2),exceeding commercial Pt/C(437 mW/cm^(2)),DCD-Pt/C(539 m W/cm^(2))and CA-Pt/C(511 mW/cm^(2))with the same loading.

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological,curing and thermal properties of epoxy nanocomposites

Poor interfacial adhesion and dispersity severely obstruct the continued development of carbon nanotube(CNT)-reinforced epoxy(EP)for potential applications.Herein,hierarchical CNT nanohybrids using nickel phyllosilicate(Ni-PS)as surface decorations(CNT@Ni-PS)were synthesized,and the nanocomposites derived from varied mass fractions of EP and CNT@Ni-PS were prepared.The morphological structures,tribological performances,curing behaviors and thermal properties of EP/CNT@Ni-PS nanocomposites were carefully investigated.Results show that hierarchical CNT nanohybrids with homogeneous dispersion and well-bonded interfacial adhesion in the matrix are successfully obtained,presenting significantly improved thermal and tribological properties.Moreover,analysis on cure kinetics proves the excellent promotion of CNT@Ni-PS on the non-isothermal curing process,lowering the curing energy barrier steadily.

Ultra-thin ALD CoO_(x)-ZnO heterogenous films as highly sensitive and environmentally friendly H_(2)S sensor

To obtain environmentally friendly,integrated and miniaturized gas sensors for the increasing request for the Internet of Things industry and other relative areas,the ultra-thin CoO_(x)/Zn O heterogeneous film with active interfacial sites was in-situ deposited on micro-electro-mechanical systems(MEMS)as H_(2)S sensor.Atomic layer deposition(ALD)was employed to in-situ fabricate the uniform Zn O thin film.ALD CoO_(x)was deposited on ZnO surface to obtain CoO_(x)/Zn O heterojunction and active interfacial sites.The ultra-thin film(20 nm)with 50 ALD Co O_(x)decorated on 250 ALD Zn O displays excellent sensing performance,including very high response(4.45@200×10^(-9))and selectivity to H_(2)S with a limit of detection(LOD)of 0.38×10^(-9),long-term sensing stability,high response/recovery performance(7.5 s/15.7 s)and mechanical strength at 230。C.Reasons for the high sensing performance of CoO_(x)/Zn O have been confirmed by series of characterizations and density functional theory(DFT)calculation.Heterojunction film thickness with Debye length,the oxygen vacancies and the synergistic effect of active interfacial sites are main reasons for the high sensing performance.The strategy by fabrication of CoO_(x)/Zn O heterogeneous film within Debye length and employing synergistic effect of active interfacial sites offers a promising route for the design of environmentally friendly gas sensors.Furthermore,the ALD technique offers a facile in-situ strategy and high-throughput fabrication of MEMS gas sensors.