In situ sulfur-doped mesoporous tungsten oxides for gas sensing toward benzene series

Benzene series as highly toxic gases have inevitably entered human life and produce great threat to human health and ecological environment,and thus it is distinctly meaningful to monitor benzene series with quickly,real-time and efficient technique.Herein,novel sulfur-doped mesoporous WO_(3)materials were synthesized via classical in-situ solvent evaporation induced co-assembly strategy combined with doping engineering,which possessed highly crystallized frameworks,high specific surface area(40.9–63.8 m^(2)/g)and uniform pore size(~18 nm).Benefitting from abundant oxygen vacancy and defects via S-doping,the tailored mesoporous S/m WO_(3)exhibited excellent benzene sensing performance,including high sensitivity(50 ppm vs.48),low detection limit(ca.500 ppb),outstanding selectivity and favorable stability.In addition,the reduction of band gap resulted from S-doping promotes the carrier migration in the sensing materials and the reaction at the gas–solid sensing interfaces.It provides brand-new approach to design sensitive materials with multiple reaction sites.

Tailored ionically conductive graphene oxide-encased metal ions for ultrasensitive cadaverine sensor

Intelligent chemical sensors have been extensively used in food safety and environmental assessment,while limited sensitivity and homogeneity bring about huge obstacles to their practical application.Herein,novel ionically conductive sensitive materials were elaborately designed based on metal ion decorated graphene oxide(GO)via a facile and general in-situ spin-coating strategy,where the abundant functional groups(-OH and-COOH)of GO layer could provide natural binding sites for various bivalent metal cations(such as Cu^(2+),Ni^(2+),Zn^(2+),Co^(2+),and Mg^(2+))through coordination and electrostatic inter-action.The intercalated metal cations on the layered GO nanosheets can be regarded as charge carriers and complexation with targeted gas(cadaverine,Cad),which is a typical metabolites production and food degradants.By contrast,the designed GO@Cu(Ⅱ)sensor exhibited the optimal sensing performance toward Cad molecules at room temperature,including ultra-low detection limit(ca.3 nL),excellent sensitivity,and rapid low concentration detection rate(only 16 s).Interestingly,the sensor exhibited an irreversible and specific response toward Cad,while it showed a transient and reversible response to other interfering gases,implying its outstanding selectivity.In addition,the GO@Cu(Ⅱ)sensor enabled real-time monitoring of the decay progression of cheese,and it exhibited great potential for large-scale production via its excellent homogeneity.It provides an efficient approach to tailoring intelligent chemical sensors for real-time food safety monitoring and human health warning.

Optimal Nonlinear Robust Sliding Mode Control of an Excitation System Based on Mixed Linear H_(2)/H_(∞) Matrix Inequalities

In this paper,an optimal nonlinear robust sliding mode control(ONRSMC)based on mixed H_(2)/H_(∞)linear matrix inequalities(LMIs)is designed for the excitation system in a“one machine-infinite bus system”(OMIBS)to enhance system stability.Initially,the direct feedback linearization method is used to establish a mathematical model of the OMIBS incorporating uncertainties.ONRSMC is then designed for this model,employing the mixed H_(2)/H_(∞)LMIs.The chaos mapping-based adaptive salp swarm algorithm(CASSA)is introduced to fully optimize the parameters of the sliding mode control,ensuring optimal performance under a specified condition.CASSA demonstrates rapid convergence and reduced like-lihood of falling into local optima during optimization.Finally,ONRSMC is obtained through inverse transformation,exhibiting the advantages of simple structure,high reliability,and independence from the accuracy of system models.Four simulation scenarios are employed to validate the effectiveness and robustness of ONRSMC,including mechanical power variation,generator three-phase short circuit,transmission line short circuit,and generator parameter uncertainty.The results indicate that ONRSMC achieves optimal dynamic performance in various operating conditions,facilitating the stable operation of power systems following faults.

Versatile core-shell magnetic fluorescent mesoporous microspheres for multilevel latent fingerprints magneto-optic information recognition

Latent fingerprints are extremely vital for personal identification and criminalinvestigation,and potential information recognition techniques have been widelyused in the fields of information and communication electronics.Although physicalpowder dusting methods have been frequently employed to develop latent fingerprintsand most of them are carried out by using single component powders ofmicron-sized fluorescent particles,magnetic powders,or metal particles,there isstill an enormous challenge in producing high-resolution image of latent fingerprintsat different backgrounds or substrates.Herein,a novel and effectivenanoimpregnation method is developed to synthesize bifunctional magnetic fluorescentmesoporous microspheres for latent fingerprints visualization by growthof mesoporous silica(mesoSiO_(2))on magical Fe_(3)O_(4) core and then deposition offluorescent YVO4:Eu^(3+)nanoparticles in the mesopores.The obtainedFe_(3)O_(4)@mesoSiO_(2)@YVO4:Eu^(3+)microspheres possess spatially isolated magneticcore and fluorescent shell which were insulated by mesoporous silica layer.Dueto their small particle size of submicrometer scale,high magnetization and lowmagnetic remanence as well as the combined magnetic and fluorescent properties,the microspheres show superior performance in visual latent fingerprint recognitionwith high contrast,high anti-interference,and sensitivity as well as goodretention on multifarious substrates regardless of surface permeability,roughness,refraction,colorfulness,and background fluorescence interference,and it makesthem ideal candidates for practical application in fingerprint visualization andeven magneto-optic information storage.

Synthesis of molybdenum disulfide/reduced graphene oxide composites for effective removal of Pb(Ⅱ) from aqueous solutions

In this work, a facile method was adopted to synthesize molybdenum disulfide/reduced graphene oxide （MoS2/rGO） composites through an c-cysteine-assisted hydrothermal technique, The as-prepared MoS2/ rGO composites were firstly applied as adsorbents for efficient elimination of Pb（Ⅱ） ions. Batch adsorption experiments showed that the adsorption of Pb（Ⅱ） on MoS2/rGO followed pseudo-second-order kinetic model well. The adsorption of Pb（Ⅱ） was intensely pH-dependent, ionic strength-dependent at pH 〈 9.0 and ionic strength-independent at pH 〉 9,0, The presence of humic acid （HA） enhanced Pb（Ⅱ） adsorption obviously. The MoS2/rGO composites exhibited excellent adsorption capacity of 384.16 mg g 1 at pH 5.0 and T = 298.15 K, which was superior to MOS2 （279.93 mg g 1） and many other adsorbents. The thermodynamic parameters suggested that the adsorption process of Pb（Ⅱ） on MoS2/rGO composites was spontaneous （zSG＂ 〈 O） and endothermic （△H 〉 0）. The interaction of Pb（Ⅱ） and MoS2] rGO was mainly dominated by electrostatic attraction and surface comple^ation between Pb（Ⅱ） and oxygen-containing functional groups of MoS2]rGO. This work highlighted the application of MoS21rGO as novel and promising materials in the efficient elimination of Pb（Ⅱ） from contaminated water and industrial effluents in environmental pollution management.

A facile construction of heterostructured ZnO/Co_(3)O_(4) mesoporous spheres and superior acetone sensing performance

The rapid development of internet and internet of things brings new opportunities for the expansion of intelligent sensors,and acetone as a major disease detection indicator(i.e.,diabetes)making it become extremely important clinical indicator.Herein,uniform mesoporous ZnO spheres were successfully synthesized via novel formaldehyde-assisted metal-ligand crosslinking strategy.In order to adjust the pore structure of mesoporous ZnO,various mesoporous ZnO spheres were synthesized by changing weight percentage of Zn(NO_(3))_(2)·6 H_(2)O to tannic acid(TA).Moreover,highly active heterojunction mesoporous ZnO/Co_(3)O_(4)has been fabricated based on as-prepared ultra-small Co_(3)O_(4)nanocrystals(ca.3 nm)and mesoporous ZnO spheres by flexible impregnation technique.Profit from nano-size effect and synergistic effect of p-n heterojunction,mesoporous ZnO/Co_(3)O_(4)exhibited excellent acetone sensing performance with high selectivity,superior sensitivity and responsiveness.Typically,5 wt%Co_(3)O_(4)embedded mesoporous ZnO sphere showed prominent acetone response(ca.46 for 50 ppm),which was about 11.5 times higher than that in pure ZnO sensing device,and it was also endowed high cyclic stability.The nanocrystals embedded hybrid material is expected to be used as promising efficient material in the field of catalysis and gas sensing.

Gadolinium-doped mesoporous tungsten oxides:Rational synthesis,gas sensing performance,and mechanism investigation

As a typical family of volatile toxic compounds,benzene derivatives are massive emission in industrial production and the automobile field,causing serious threat to human and environment.The reliable and convenient detection of low concentration benzene derivatives based on intelligent gas sensor is urgent and of great significance for environmental protection.Herein,through heteroatomic doping engineering,rare-earth gadolinium(Gd)doped mesoporous WO_(3)with uniform mesopores(15.7–18.1 nm),tunable high specific surface area(52–55 m^(2)·g^(−1)),customized crystalline pore walls,was designed and utilized to fabricate highly sensitive gas sensors toward benzene derivatives,such as ethylbenzene.Thanks to the high-density oxygen vacancies(OV)and significantly increased defects(W^(5+))produced by Gd atoms doping into the lattice of WO_(3)octahedron,Gd-doped mesoporous WO_(3)exhibited excellent ethylbenzene sensing performance,including high response(237 vs.50 ppm),rapid response–recovery dynamic(13 s/25 s vs.50 ppm),extremely low theoretical detection limit of 24 ppb.The in-situ diffuse reflectance infrared Fourier transform and gas chromatograph-mass spectrometry results revealed the gas sensing process underwent a catalytic oxidation conversion of ethylbenzene into alcohol species,benzaldehyde,acetophenone,and carboxylate species along with the resistance change of the Gd-doped mesoporous WO_(3)based sensor.Moreover,a portable smart gas sensing module was fabricated and demonstrated for real-time detecting ethylbenzene,which provided new ideas to design heteroatom doped mesoporous materials for intelligent sensors.