Mesoporous amorphous FeOOH-encapsulated BiO_(2–x) photocatalyst with harnessing broad spectrum toward activation of persulfate for tetracycline degradation

With the growing concern about the water environment,the advanced oxidation process of persulfate activation assisted by photocatalysis has attracted considerable attention to decompose dissolved organic micropollutants.In this work,to overcome the drawbacks of the photocatalytic activity reduction caused by the photo-corrosion of non-stoichiometric BiO_(2–x),a novel material with amorphous FeOOH in situ grown on layered BiO_(2–x) to form a core-shell structure similar to popcorn chicken-like morphology was produced in two simple and environmentally beneficial steps.Through a series of degradation activity tests of hybrid materials under different conditions,the as-prepared materials exhibited remarkable degradation activity and stability toward tetracycline in the FeOOH@BiO_(2–x)/Vis/PS system due to the synergism of photocatalysis and persulfate activation.The results of XRD,SEM,TEM,XPS,FTIR,and BET show that the loading of FeOOH increases the specific surface area and active sites appreciably;the heterogeneous structure formed by FeOOH and BiO_(2–x) is more favorable to the effective separation of photogenerated carriers.The optimal degradation conditions were at a catalyst addition of 0.7 g·L^(–1),a persulfate concentration of 1.0 g·L^(–1),and an initial pH of 4.5,at which the degradation rate could reach 94.7%after 90 min.The influence of typical inorganic anions on degradation was also examined.ESR studies and radical quenching experiments revealed that·OH,SO_(4)^(-)·,and·O_(2)^(-)were the principal active species generated during the degradation of tetracycline.The results of the 1,10-phenanthroline approach proved that the effect of dissolved iron ions on the tetracycline degradation was limited,and the interfacial reaction that occurs on the active sites on the material's surface was a critical factor.This work provides a novel method for producing efficient broad-spectrum Bismuth-based composite photocatalysts and photocatalytic-activated persulfate synergistic degradation of tetracycline.

Achieving high-efficient photocatalytic persulfate-activated degradation of tetracycline via carbon dots modified MIL-101(Fe)octahedrons

The synergistic reaction of photocatalysis and advanced oxidation is a valid strategy for the degradation of harmful antibiotic wastewater.Herein,carbon dots(CDs)modified MIL-101(Fe)octahedrons to form CDs/MIL-101(Fe)composite photocatalyst was synthesized for visible light-driven photocatalytic/persulfate(PS)-activated tetracycline(TC)degradation.The electron spin resonance(ESR)spectra,scavenging experiment and electrochemical analysis were carried out to reveal that the high visible light-driven photocatalytic degradation activity of TC over CDs/MIL-101(Fe)photocatalysts is not only ascribed to the production of free active radicals in the CDs/MIL-101(Fe)/PS system(·OH,·SO_(4-),^(1)O_(2),h^(+)and·O_(2)^(-))but also attributed to the consumption of electrons caused by the PS,which can suppress the recombination of photo-generated carriers as well as strong light scattering and electron trapping effects of CDs.Finally,the possible degradation pathways were proposed by analyzing intermediates via liquid chromatography-mass spectrometry technique.This research presents a rational design conception to construct a CDs/PS-based photocatalysis/advanced oxidation technology with high-efficient degradation activity for the remediation of organic antibiotic pollutant wastewater and for the improvement of carrier transport kinetics of photocatalysts.

Carbon-doped CuFe_(2)O_(4) with C-O-M channels for enhanced Fenton-like degradation of tetracycline hydrochloride: From construction to mechanism

Carbon-doped copper ferrite(C–CuFe_(2)O_(4))was synthesized by a simple two-step hydrothermal method,which showed enhanced tetracycline hydrochloride(TCH)removal efficiency as compared to the pure CuFe_(2)O_(4) in Fenton-like reaction.A removal efficiency of 94%was achieved with 0.2 g L^(-1) catalyst and 20 mmol L^(-1) H_(2)O_(2) within 90 min.We demonstrated that 5%C–CuFe_(2)O_(4) catalyst in the presence of H_(2)O_(2) was significantly efficient for TCH degradation under the near-neutral pH(5–9)without buffer.Multiple techniques,including SEM,TEM,XRD,FTIR,Raman,XPS M€ossbauer and so on,were conducted to investigate the structures,morphologies and electronic properties of as-prepared samples.The introduction of carbon can effectively accelerate electron transfer by cooperating with Cu and Fe to activate H_(2)O_(2) to generate·OH and·O_(2)^(-).Particularly,theoretical calculations display that the p,p,d orbital hybridization of C,O,Cu and Fe can form C–O–Cu and C–O–Fe bonds,and the electrons on carbon can transfer to metal Cu and Fe along the C–O–Fe and C–O–Cu channels,thus forming electron-rich reactive centers around Fe and Cu.This work provides lightful reference for the modification of spinel ferrites in Fenton-like application.

Cadmium sulfide cage photocatalysis coupled electroactive biofilm for synergistic promotion of tetracycline degradation and electricity production

Tetracycline(TC)as a common broad-spectrum antibiotic,has been frequently detected in soil and sur-face water.It becomes a great threat to the ecological environment.Here,a device of photocatalysis as-sisted microbial fuel cell(photo-MFC)was constructed for TC degradation and energy recovery.In this photo-MFC,cadmium sulfide(CdS)cage photocatalysis can degrade most of TC in a short time.While the Co_(3)O_(4)@C-CC(carbonization and calcination of the ZIF-67 precursor in-situ grown on the carbon cloth(CC))bioanode degrades the rest of TC as well as the photocatalytic products,thus improving the miner-alization.The co-existence of photocatalysis with bioanode changes the microbial community structure of the biofilms.The dominant phylum is Geobacter(60.2%)in normal MFC while that in photo-MFC are Pro-teobacteria(43.5%)and Geobacter(33.2%).Therefore,the synergistic effect of photocatalytic degradation and biodegradation achieves a chemical oxygen demand(COD)removal of 98.6%,which is higher than that of normal MFC(77.6%)or single CdS cage photocatalysis(23.8%).In addition,the photogenerated electrons can be transferred to the cathode,which reduces their combination with holes and increases the electricity generation of MFC,achieving a maximum power density of 3.37 W/m^(2).After degradation,the effluent with 200 mg L^(−1) TC exhibits no visible biotoxity.Furthermore,electrochemical test,finite-difference time-domain(FDTD),density functional theory(DFT)calculation and the free radical trapping experiments verify the possible mechanisms of photocatalytic degradation in this photo-MFC.This strat-egy paves a new way for low energy consumption removal and energy recovery of organic pollutants.

A study on singlet oxygen generation for tetracycline degradation via modulating the size ofα-Fe_(2)O_(3)nanoparticle anchored on g-C_(3)N_(4) nanotube photocatalyst

Photocatalysis is considered as an effective technique for mitigating ecological risks posed by residual tetracycline(TC).To improve the efficiency of this technique,it is necessary to enable photocatalysts to produce highly reactive species,such as singlet oxygen(1O2).However,due to the high activation energy of 1O2,photocatalysts can hardly produce 1O2 without assistance from external oxidants.Herein,we find that the size-reducedα-Fe_(2)O_(3)nanoparticles(~4 nm)that anchored on g-C_(3)N_(4)nanotube(α-Fe_(2)O_(3)@CNNT)can spontaneously generate ^(1)O_(2) for degradation of TC.In comparison,only hydroxyl radical(·OH)can be produced by g-C_(3)N_(4)nanotube loaded with~14 nmα-Fe_(2)O_(3)nanoparticles(α-Fe_(2)O_(3)/CNNT).Owing to the high reactivity of the ^(1)O_(2) species,the photocatalytic degradation rate(Kapp)of TC withα-Fe_(2)O_(3)@CNNT(0.056 min^(−1))was 1.8 times higher than that ofα-Fe_(2)O_(3)/CNNT.The experimental results and theoretical calculations suggested that reducing the size ofα-Fe_(2)O_(3)nanoparticles anchored on g-C_(3)N_(4)nanotube decreased the surface electron density ofα-Fe_(2)O_(3),which induces the generation of high-valent Fe(IV)active sites overα-Fe_(2)O_(3)@CNNT and turns the degradation pathway into a unique ^(1)O_(2) dominated process.This study provides a new insight on the generation of ^(1)O_(2) for effective degradation of environmental pollutant.

Synergistic CO_(2)reduction and tetracycline degradation by CuInZnS-Ti_(3)C_(2)T_(x)in one photoredox cycle

Optimizing photocatalytic CO_(2)reduction with simultaneous pollutant degradation is highly desired.However,the photocatalytic efficiency is restricted by the unmatched redox ability,high carriers’recombination rate,and lack of reactive sites of the present photocatalysts.Herein,the CuInZnS-Ti_(3)C_(2)T_(x)hybrid with matched redox ability and suitable CO_(2)adsorption property was rationally synthesized.The nucleation and growth process of CuInZnS was interfered by the addition of Ti_(3)C_(2)T_(x)with a negative charge,resulting in thinner nanosheets and richer reactive sites.Besides,the Schottky heterojunction built in the hybrid simultaneously improved the photoexcited charge transfer property,sunlight absorption range,and CO_(2)adsorption ability.Consequently,upon exposure to sunlight,CuInZnS-Ti_(3)C_(2)T_(x)exhibited an efficient photocatalytic CO_(2)reduction performance(10.2μmol·h^(−1)·g^(−1))with synergetic tetracycline degradation,obviously higher than that of pure CuInZnS.Based on the combination of theoretical calculation and experimental characterization,the photocatalytic mechanism was investigated comprehensively.This work offers a reference for the remission of worldwide energy shortage and environmental pollution problems.

Polar solvent induced in-situ self-assembly and oxygen vacancies on Bi_(2)MoO_(6)for enhanced photocatalytic degradation of tetracycline

It has been proved to be an effective route to efficiently ameliorate photocatalytic performance of catalysts via designing three-dimensional(3D)hierarchical nanostructures and constructing oxygen vacancies(VOs).However,controlling the self-assembly of organization into 3D hierarchical nanostructures while introducing VOs in photocatalysts remains a challenge.Herein,we reported an ethylene glycol(EG)mediated approach to craft 3D hydrangea-structure Bi_(2)MoO_(6)with VOs for efficient photocatalytic degradation of tetracycline.Through manipulating the EG concentration during the fabrication process,the influence of EG concentration on the Bi_(2)MoO_(6)structure was systematically investigated.EG could promote the self-assembly of Bi_(2)MoO_(6)nanosheets to form a 3D hierarchical structure.Compared with 2D nanoplates,3D hierarchical architecture enhanced the surface area and the amount of active sites of Bi_(2)MoO_(6).In addition,the reduction effect of EG on metallic oxide enabled the generation of VOs in Bi_(2)MoO_(6).The VOs adjusted the electronic structure of Bi_(2)MoO_(6),which not only enhanced the light harvesting,but also facilitated the simultaneous utilization of photo-induced electrons and holes to form reactive oxygen species(·O2−and·OH)for the efficient tetracycline decomposition.3D Bi_(2)MoO_(6)hydrangea with VOs achieved a 79.4%removal efficiency of tetracycline after 75 min.This work provides a simple yet robust EG-mediated strategy,which not only promotes the self-assembly of nano-catalysts into 3D hierarchical architectures,but also crafts tunable VOs for highly efficient photocatalysis.

Assembling Superfine Bi_(3)TaO_(7) Particles into 2D Fe_(2)O_(3) Nanosheets for Enhanced Usability to Aqueous Tetracycline Residues

Composites of 2D/0D Fe_(2)O_(3)-Bi_(3)TaO_(7)(FO-BTO)prepared by a hydrothermal method in which superfine Bi_(3)TaO_(7) particles were mounted onto lamellae of Fe_(2)O_(3) sheets could efficiently remove aqueous tetracycline(TC)residues.The optimal composite FO-3BTO had a TC removal rate of 95%in 120 min under solar light,and its overall properties were better than those of reported photocatalysts.According to XRD,HRTEM,XPS,SEM,PL,EIS,and photocurrent tests,Fe_(2)O_(3) and Bi_(3)TaO_(7) composites formed on effective S-scheme heterojunctions,and the tight contact structure contributed to the increase in efficiency of aqueous TC residue removal.

Nonradical-dominated peroxymonosulfate activation through bimetallic Fe/Mn-loaded hydroxyl-rich biochar for efficient degradation of tetracycline

Biochar-based transition metal catalysts have been identified as excellent peroxymonosulfate(PMS)activators for producing radicals used to degrade organic pollutants.However,the radical-dominated pathways for PMS activation severely limit their practical applications in the degradation of organic pollutants from wastewater due to side reactions between radicals and the coexisting anions.Herein,bimetallic Fe/Mn-loaded hydroxyl-rich biochar(FeMn-OH-BC)is synthesized to activate PMS through nonradical-dominated pathways.The as-prepared FeMn-OH-BC exhibits excellent catalytic activity for degrading tetracycline at broad pH conditions ranging from 5 to 9,and about 85.0%of tetracycline is removed in 40 min.Experiments on studying the influences of various anions(HCO_(3)^(−),NO_(3)^(−),and H_(2)PO_(4)^(−))show that the inhibiting effect is negligible,suggesting that the FeMn-OHBC based PMS activation is dominated by nonradical pathways.Electron paramagnetic resonance measurements and quenching tests provide direct evidence to confirm that 1O2 is the major reactive oxygen species generated from FeMn-OH-BC based PMS activation.Theoretical calculations further reveal that the FeMn-OH sites in FeMn-OH-BC are dominant active sites for PMS activation,which have higher adsorption energy and stronger oxidative activity towards PMS than OH-BC sites.This work provides a new route for driving PMS activation by biochar-based transition metal catalysts through nonradical pathways.

Combination tanning mechanism inspired environmentally benign catalyst for efficient degradation of tetracycline

The utilization of chelation reaction between metals and tannins is a common tanning method in leather chemistry.Herein,a novel combination tanning mechanism inspired environmentally benign catalyst(CMBT-Fe^(0))was synthesized by immobilizing Fe nanoparticles onto bayberry tannin(BT)grafted chitosan microfibers(CM).The obtained catalyst featured a well-defined microfibrous structure,on which Fe^(0)nanoparticles were highly dispersed to exhibit exceptional catalytic activity for the degradation of tetracycline(TC).The catalytic activity of CMBT-Fe^(0)was 1.72 times higher than that of the commercial Fe^(0)nanoparticles without immobilization,with 95.03%of TC degraded within 90.0 min.The CMBT-Fe^(0)catalysts were recycled 6 times,with the removal rate of TC maintained at 82.56%.Furthermore,a possible mechanism responsible for the catalytic removal of TC was provided by analyzing the catalytic degradation products via liquid chromatography-mass spectrometry.Therefore,our investigation successfully developed efficient catalysts to address the concerned environmental issue of antibiotic pollution.

Efficient photocatalysis of tetracycline hydrochloride(TC-HCl) from pharmaceutical wastewater using AgCl/ZnO/g-C_(3)N_(4) composite under visible light: Process and mechanisms

AgCl/ZnO/g-C_(3)N_(4), a visible light activated ternary composite catalyst, was prepared by combining calcination, hydrothermal reaction and in-situ deposition processes to treat/photocatalyse tetracycline hydrochloride(TC-HCl) from pharmaceutical wastewater under visible light. The morphological, structural, electrical, and optical features of the novel photocatalyst were characterized using scanning electron microscopy(SEM), UV-visible light absorption spectrum(UV–Vis DRS), X-ray diffractometer(XRD), Fourier transform infrared spectroscopy(FT-IR), X-ray photoelectron spectroscopy(XPS), and transient photocurrent techniques. All analyses confirmed that the formation of heterojunctions between AgCl/ZnO and g-C_(3)N_(4)significantly increase electron-hole transfer and separation compared to pure ZnO and g-C_(3)N_(4). Thus, AgCl/ZnO/g-C_(3)N_(4)could exhibit superior photocatalytic activity during TC-HCl assays(over 90% removal) under visible light irradiation. The composite could maintain its photocatalytic stability even after four consecutive reaction cycles. Hydrogen peroxide(H_(2)O_(2)) and superoxide radical(·O_(2)) contributed more than holes(h+) and hydroxyl radicals(·OH) to the degradation process as showed by trapping experiments. Liquid chromatograph-mass spectrometer(LC-MS) was used for the representation of the TC-HCl potential degradation pathway. The applicability and the treatment potential of AgCl/ZnO/gC_(3)N_(4)against actual pharmaceutical wastewater showed that the composite can achieve removal efficiencies of 81.7%, 71.4% and 69.0% for TC-HCl, chemical oxygen demand(COD) and total organic carbon(TOC) respectively. AgCl/ZnO/g-C_(3)N_(4)can be a prospective key photocatalyst in the field of degradation of persistent, hardly-degradable pollutants, from industrial wastewater and not only.

Novel Ag-bridged dual Z-scheme g-C_(3)N_(4)/BiOI/AgI plasmonic heterojunction: Exceptional photocatalytic activity towards tetracycline and the mechanism insight

Rational design and synthesis of highly efficient and robust photocatalysts with positive exciton splitting and interfacial charge transfer for environmental applications is critical.Herein,aiming at overcoming the common shortcomings of traditional photocatalysts such as weak photoresponsivity,rapid combination of photo-generated carriers and unstable structure,a novel Ag-bridged dual Z-scheme g-C_(3)N_(4)/BiOI/AgI plasmonic heterojunction was successfully synthesized using a facile method.Results showed that Ag-AgI nanoparticles and three-dimensional(3D)BiOI microspheres were decorated highly uniformly on the 3D porous g-C_(3)N_(4) nanosheet,resulting in a higher specific surface area and abundant active sites.The optimized 3D porous dual Z-scheme g-C_(3)N_(4)/BiOI/Ag-AgI manifested exceptional photocatalytic degradation efficiency of tetracycline(TC)in water with approximately 91.8%degradation efficiency within 165 min,outperforming majority of the reported g-C_(3)N_(4)-based photocatalysts.Moreover,g-C_(3)N_(4)/BiOI/Ag-AgI exhibited good stability in terms of activity and structure.In-depth radical scavenging and electron paramagnetic resonance(EPR)analyses confirmed the relative contributions of various scavengers.Mechanism analysis indicated that the improved photocatalytic performance and stability were ascribed to the highly ordered 3D porous framework,fast electron transfer of dual Z-scheme heterojunction,desirable photocatalytic performance of BiOI/AgI and synergistic effect of Ag plasmas.Therefore,the 3D porous Z-scheme g-C_(3)N_(4)/BiOI/Ag-AgI heterojunction had a good prospect for applications in water remediation.The current work provides new insight and useful guidance for designing novel structural photocatalysts for environment-related applications.

In situ meso-tetra(4-carboxyphenyl)porphyrin ligand substitution in Hf-MOF for enhanced catalytic activity and stability in photoredox reactions

Though there are numerous intrinsic merits of metal-organic frameworks(MOFs),low charge separation efficiency has imposed heavy restrictions on their photocatalytic application.Herein,in situ porphyrin ligand substitution,as a strategy for improving the charge separation efficiency and increasing the amounts of active sites,has been designed and realized in a Hf-biphenyl dicarboxylic acid(BPDC)MOF.Specifically,a size and geometry matched meso-tetra(4-carboxyphenyl)porphyrin(TCPP)ligand was selected and doped into Hf-BPDC MOF by forming coordinating bonds with Hf centers,forming dualligand Hf-BPDC-TCPP MOF.The resultant Hf-BPDC-TCPP MOF showed significantly improved activity and chemical stability in the photocatalytic H_(2)generation(261μmol·g^(-1)·h^(-1))and tetracycline(TC)degradation reactions(95.8%),which was 48 and 1.47 folds higher than that of the Hf-BPDC MOF.Photophysical and electrochemical studies revealed that the introduction of porphyrin ligand could generate a stronger internal electric field for boosting the charge separation and transfer,increase the specific surface area for providing more active sites,and narrow the band gap to enhance the visible light absorption.This in situ ligand substitution method provides a promising approach to build a tunable platform for constructing high-performance MOF photocatalysts.

Facile synthesis of GO as middle carrier modified flower-like BiOBr and C_(3)N_(4) nanosheets for simultaneous treatment of chromium(Ⅵ)and tetracycline

A novel GO modified g-C_(3)N_(4) nanosheets/flower-like BiOBr hybrid photocatalyst is fabricated by a facile method.The characterization results reveal that wrinkled GO is deposited between g-C_(3)N_(4) nanosheets and flower-like BiOBr forming a Z-scheme heterojunction.As a mediator,plicate GO plays a positive role in prompting photogene rated electrons transfe rring through its sizeable 2 D/2 D contact surface area.The g-C3 N4/GO/BiOBr hybrid displays a superior photocatalytic ability to g-C_(3)N_(4) and BiOBr in photodegrading tetracycline(TC),whose removal efficiency could reach 96%within 2 h.Besides,g-C_(3)N_(4)/GO/BiOBr composite can reduce Cr(Ⅵ),and simultaneously treat TC and Cr(Ⅵ)combination contaminant under the visible light The g-C_(3)N_(4)/GO/BiOBr ternary composite also exhibits satisfactory stability and reusability after four cycling experiments.Further,a feasible mechanism related to the photocatalytic process of gC_(3)N_(4)/GO/BiOBr is put forward.This study offers a te rnary hybrid photocatalyst with eco-friendliness and hopeful application in water pollution.

Coupled Cu doping and Z-scheme heterojunction for synergistically enhanced tetracycline photodegradation

Semiconductor-based photocatalysis by utilizing solar energy for sustainable organic pollutant elimination has been a promising tactic to alleviate environmental issues.Nevertheless,the development of robust and efficient photocatalysts to degrade organic pollutants still faces major challenges because of insufficient charge separation.Here we design and fabricate a heterojunction consisting of copper,carbon-modified TiO_(2),and sulfur-doped g-C_(3)N_(4)nanosheets(i.e.,S-C_(3)N_(4)/Cu/C-TiO_(2)).The heterostructure affords a remarkable synergistic photocatalysis for tetracycline hydrochloride degradation,achieving an 82.6%removal efficiency within 30 min under visible light irradiation,about 15.4 and 7.3 times higher than that of S-C_(3)N_(4)and C-TiO_(2),respectively.The superior performance is attributed to the synergy between Cu doping and the Z-scheme heterojunction,which not only enhances the interfacial electric field effect,facilitating charge separation,but also boosts the redox capability.The charge carrier transfer between Cu/C-TiO_(2)and S-C_(3)N_(4)follows a Z-scheme,as verified by trapping experiments,electron spin-resonance spectroscopy,and density functional theory calculations.Furthermore,the tetracycline hydrochloride degradation pathways are enunciated by liquid chromatograph mass spectrometry analysis.This work provides an effective approach for constructing high-performance photocatalysts that have potential in environmental remediation.

Decoration of CdMoO_(4) micron polyhedron with Pt nanoparticle and their enhanced photocatalytic performance in N_(2) fixation and water purification

This study aimed to prepare and apply a novel Pt/CdMoO_(4) composite photocatalyst for photocatalytic N2 fixation and tetracycline degradation. The Pt/CdMoO_(4) composite was subjected to comprehensive investigation on the morphology, structure, optical properties, and photoelectric chemical properties. The results demonstrate the dispersion of Pt nanoparticles on the CdMoO_(4) surface. Close contact between CdMoO_(4) and Pt was observed, resulting in the formation of a heterojunction structure at their contact region. Density functional theory calculation and Mott-Schottky analysis revealed that Pt possesses a higher work function value than CdMoO_(4), resulting in electron drift from CdMoO_(4) to Pt and the formation of a Schottky barrier. The presence of this barrier increases the separation efficiency of electron-hole pairs, thereby improving the performance of the Pt/CdMoO_(4) composite in photocatalysis. When exposed to simulated sunlight, the optimal Pt/CdMoO_(4) catalyst displayed a photocatalytic nitrogen fixation rate of 443.7 μmol·L‒^(1)·g‒^(1)·h‒^(1), which is 3.2 times higher than that of pure CdMoO_(4). In addition, the composite also exhibited excellent performance in tetracycline degradation, with hole and superoxide species identified as the primary reactive species. These findings offer practical insights into designing and synthesizing efficient photocatalysts for photocatalytic nitrogen fixation and antibiotics removal.

Continuous polypyrrole nanotubes encapsulated Co_(3)O_(4)nanoparticles with oxygen vacancies and electron transport channels boosting peroxymonosulfate activation

Co_(3)O_(4)particles are promising heterogeneous catalysts for peroxymonosulfate(PMS)activation;whereas they still surfer from the extensive agglomeration,serious Co leaching,poor electronic conductivity,and difficult recovery.Herein,a novel hybrid nanoarchitectonic constructed by encapsulating Co_(3)O_(4)nanoparticles into continuous polypyrrole(PPy)nanotubes(Co_(3)O_(4)@PPy hybrids)was developed using electrospun fibers as the templates,which boosted the catalytic degradation toward tetracycline(TC).The continuous polypyrrole nanotubes could provide the confined spaces,offer effective electron transfer pathway,suppress cobalt ion loss,facilitate the oxygen vacancy(Ovac)formation,and accelerate the Co^(2+)/Co^(3+)cycles.Co_(3)O_(4)@PPy hybrids thereby exhibited a remarkably enhanced catalytic activity with the TC degradation efficiency of 97.2%(kobs=0.244 min^(−1))within 20 min and total organic carbon(TOC)removal rate of 66.8%.Furthermore,the recycle test,real natural water treatment,and fluidized-column catalytic experiments indicated the potential of Co_(3)O_(4)@PPy hybrids in the practical large-scale applications.

Carbon self-doped polytriazine imide nanotubes with optimized electronic structure for enhanced photocatalytic activity

The triazine-based carbon nitride known as polytriazine imide(PTI)is a metal-free semiconductor photocatalyst but usually shows moderate activity due to its limited charge transfer mobility.Here,carbon self-doped PTI(C-PTI)was prepared via a facile and green method by using glucose as the carbon source.In the condensation process,glucose can promote nanotube formation,giving the product larger surface areas.Moreover,carbon self-doping induces an intrinsic change in the electronic structure,thus optimizing the band structure and the electronic transport property.Therefore,the as-synthesized C-PTI exhibits remarkably enhanced photocatalytic activities for both hydrogen evolution and tetracycline degradation reactions.