Light Adsorption Research Articles

Synthesis of Fe-MOFs/h-CeO2 hollow micro-spheres and their highly efficient photocatalytic degradation of RhB

A series of Fe-MOFs/h-CeO2 composite photocatalysts were synthesized by a hydrothermal method using cerium oxide hollow microspheres as carriers, naphthalene dicarboxylic acid as an organic ligand, and iron as a metal center. The obtained samples were characterized by XRD, SEM, TEM, UV-Vis, XPS, and PL. It shows that the samples contained hollow CeO2 microspheres with a diameter of about 500 nm as the carrier, and the surface was a burr-like shell coated with Fe-MOFs about 100 nm. The bandgap of Fe-MOFs/h-CeO2 was reduced to 1.62 eV; the photocatalytic performance was tested via RhB degradation. The results indicate that the Fe-MOFs/h-CeO2 composites show enhanced photocatalytic activity, in contrast with CeO2 hollow microspheres. All of this can be attributed to the that the MOFs fabricated could not only improve the light adsorption through the outer shells and provide more active sites but also enhance charge carriers. It is expected that this study could provide helpful results for fabricating and exploration of composite catalysts with tunable photocatalytic performance.

Synthesis and photocatalytic activity of Cu2O hollow nanospheres/TiO2 nanosheets by an in-situ water-bath method

In this work, a simple in-situ water-bath method is used to load Cu2O hollow nanospheres (named as H-Cu2O) on TiO2 nanosheets (named as TiO2-NS). H-Cu2O of 160–250 nm in diameter is uniformly supported on the surface of TiO2-NS. H-Cu2O has a novel hollow core-shell structure with a double shell. Specifically, the diameters of inner hollow spheres are 80–90 nm and the thickness of the outer shell and inner shell are about 40 nm and 25 nm, respectively. It is conjectured that the outer and inner shells of H-Cu2O can both provide adsorption and reaction sites, favoring the photocatalytic reaction. The UV–visible diffused reflectance spectra show that compared with TiO2-NS, the H-Cu2O/TiO2-2 sample with adding 80 mg of TiO2-NS shows a stronger visible light absorption. Furthermore, the steady-state photoluminescence (PL) and photocurrent spectra show that H-Cu2O/TiO2-2 has a weaker PL intensity at about 370 nm and 6 times higher photocurrent intensity than TiO2-NS, demonstrating that H-Cu2O/TiO2-2 has higher charge separation efficiency. Compared with TiO2-NS, the photocatalytic activity of H-Cu2O/TiO2-2 under UV light (λ ≤ 400 nm) increase by 6.3 times for the degradation of methyl orange. The improved photocatalytic activity can be attributed to the enlarged BET areas (6.1 m2 g-1/H-Cu2O/TiO2-2 vs. 3.8 m2 g-1/TiO2-NS), the enhanced light adsorption, and the improved charge separation efficiency. The reported in-situ water-bath method is simple, mild, and general, which could be extended to other novel composite materials.

Fabrication of Adsorbed Fe(III) and Structurally Doped Fe(III) in Montmorillonite/TiO2 Composite for Photocatalytic Degradation of Phenol

The Fe(III)-doped montmorillonite (Mt)/TiO2 composites were fabricated by adding Fe(III) during or after the aging of TiO2/Ti(OH)4 sol–gel in Mt, named as xFe-Mt/(1 − x)Fe-TiO2 and Fe/Mt/TiO2, respectively. In the xFe-Mt/(1 − x)Fe-TiO2, Fe(III) cations were expected to be located in the structure of TiO2, in the Mt, and in the interface between them, while Fe(III) ions are physically adsorbed on the surfaces of the composites in the Fe/Mt/TiO2. The narrower energy bandgap (Eg) lower photo-luminescence intensity were observed for the composites compared with TiO2. Better photocatalytic performance for phenol degradation was observed in the Fe/Mt/TiO2. The 94.6% phenol degradation was due to greater charge generation and migration capacity, which was confirmed by photocurrent measurements and electrochemical impedance spectroscopy (EIS). The results of the energy-resolved distribution of electron traps (ERDT) suggested that the Fe/Mt/TiO2 possessed a larger amorphous rutile phase content in direct contact with crystal anatase than that of the xFe-Mt/(1 − x)Fe-TiO2. This component is the fraction that is mainly responsible for the photocatalytic phenol degradation by the composites. As for the xFe-Mt/(1 − x)Fe-TiO2, the active rutile phase was followed by isolated amorphous phases which had larger (Eg) and which did not act as a photocatalyst. Thus, the physically adsorbed Fe(III) enhanced light adsorption and avoided charge recombination, resulting in improved photocatalytic performance. The mechanism of the photocatalytic reaction with the Fe(III)-doped Mt/TiO2 composite was proposed.

Synthesis of novel BiOBr/Bio-veins composite for photocatalytic degradation of pollutants under visible-light

A novel BiOBr/Bio-vein photocatalyst was synthesized with a wet drop addition method, where the substrate biological veins (Bio-veins) were obtained with a green and environmentally-friendly multiple route. BiOBr/Bio-veins composite show larger visible light adsorption compared with pure BiOBr, and the size of BiOBr nanosheet from BiOBr/Bio-veins composite is smaller than that of pure BiOBr. BiOBr/Bio-veins composite shows highly photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. Reactive species trapping experiments and electron paramagnetic resonance (EPR) tests were used to explore photodegradation mechanism of BiOBr/Bio-veins, which demonstrated that superoxide radicals (•O2−) and holes (h+) were the main active groups for photocatalytic degradation. Moreover, BiOBr/Bio-veins composite can be easily recovered without centrifugation and filtration. This study provides novel natural biological materials to immobilize photocatalyst particles with highly photocatalytic degradation of pollutants.

Feasibility study of municipal wastewater removal synchronized with electricity generation via solar-driven photocatalytic fuel cell with Bi2WO6/ZnO nanorods array photoanode

The reclamation of energy from municipal wastewater treatment process is highly demanded and could resolve the two most formidable dilemmas of water pollution and energy crisis nowadays. In this study, a photocatalytic fuel cell (PFC) utilizing a Z-scheme heterojunction Bi2WO6/ZnO nanorod arrays (NRAs) photoanode was employed for efficient municipal wastewater treatment and electricity generation simultaneously under sunlight irradiation. Various characterization techniques, including energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), transient photoresponse (TPR), and linear sweep voltammetry (LSV) were used to analyze the physical, chemical and photoelectrochemical characteristics of the as-synthesized photoanode. The results indicated that the Z-scheme heterojunction Bi2WO6/ZnO NRAs exhibited the excellent photocatalytic performance under sunlight irradiation as compared to pristine ZnO NRAs. Ergo, the PFC system achieved complete removal of COD and produced 3.30 μW cm−2, 37.10 μA cm−2 and 563 mV of maximum power density (Pmax ), short-current density (Jsc) and open-circuit voltage (Voc) within 4 h of sunlight irradiation, respectively. The boosted photoactivity was ascribed to the successful formation of the Z-scheme hybridization interface betwixt the Bi2WO6 and ZnO NRAs, that not only enhanced the visible light adsorption of ZnO NRAs, concomitantly significantly accelerated the spatial charge separation and restrained the electron-hole pair recombination.

Morphology controlling strategy of ZnS/CeO2 catalysts to enhance the photocatalytic performance for hydrogen production

Semiconductor photocatalysts have been utilized to convert solar energy into hydrogen. However, CeO 2 has been rarely reported as a photocatalyst for hydrogen production on account of the rapid photoelectron-hole pair recombination and limited visible light adsorption capacity. In this work, we present the morphology controlling strategy on the purpose of preparing efficient composite semiconductor photocatalysts of CeO 2 with regular shape and reliable performance. The synthesized photocatalysts ZnS/CeO 2 with completely different morphologies structure (ZnS/CeO 2 solid spheres and ZnS/CeO 2 hollow dodecahedra) were obtained by a similar method. The results show that with the expansion of the visible light absorption range and the increase of nano pore porosity, the two photocatalysts ZnS/CeO 2 can afford more active sites and promote the transfer of photogenerated electrons-holes, thus effectively improving the hydrogen production efficiency. Besides, both of the photocatalysts ZnS/CeO 2 exhibit the long term (25 ​h) stability that also indicates a great potential in the photocatalytic water splitting for hydrogen evolution. This work provides a new idea and research method for further research on hydrogen production from photolysis of water.

Metal-Organic Framework-Derived Tubular In2O3-C/CdIn2S4 Heterojunction for Efficient Solar-Driven CO2 Conversion.

Realizing high-efficiency solar-driven CO2 reduction to chemicals and fuels requires high-performance photocatalysts with high utilization efficiency of solar light, efficient charge separation and transfer, and robust adsorption capacity for CO2. In this work, a tubular In2O3-C/CdIn2S4 (IOC/CIS) ternary heterojunction with an intimate interfacial contact was fabricated by pyrolysis of In-MIL-68 and subsequent solvothermal synthesis of CdIn2S4. The construction of a heterojunction promotes the separation and transfer efficiency of photogenerated carriers. The introduction of carbon not only accelerates the interfacial charge migration but also enhances light absorption and CO2 adsorption. The resulting 5IOC/CIS sample presents a remarkably improved photocatalytic CO2 reduction activity with a CO generation rate of 2432 μmol g-1 h-1, much higher than that of the In2O3/CdIn2S4 (IO/CIS) heterojunction (1906 μmol g-1 h-1). Furthermore, the type II charge transfer mechanism of the heterojunction was confirmed by the electron paramagnetic resonance characterization. This work provides new insight into the design and preparation of a highly efficient hollow heterojunction for photocatalytic applications.

Electronic and optical properties and device applications for antimonene/WS2 van der Waals heterostructure

The antimonene and WS2 monolayers have widely studied recently. Here, we construct the Sb/WS2 van der Waals heterostructures to explore their combined effects on electronic and optical properties based on density functional method. The calculated results show that the most stable heterostructure is a type-Ⅱ semiconductor with a medium band gap of 1.183 eV. The external electric field can alter its band gap significantly, for example, the small negative electric field can make the band gap narrowed sharply and linearly. Based on this behavior, a high-performance heterostructure Schottky-barrier field effect transistor is designed. And under vertical strain, the heterostructure is robust to sustain a type-Ⅱ band alignment, but the band gap can be reduced rapidly by pressure. Accordingly, a strain-gated high switch-ratio mechanical switch device by working reversibly between the “compressive” and “unstrained” states is suggested. Also shown is that this heterostructure prefers the visible light adsorption, and the photoelectric power conversion efficiency (PCE) is as high as 20.98%. Particularly, under small positive electric field, the light adsorption and PCE for this heterostructure is enhanced significantly up to 22.845%. Thus a photovoltaic cell with a high PCE is proposed.

Preparation, performance and mechanism of p-Ag3PO4/n-ZnO/C heterojunction with IRMOF-3 as precursor for efficient photodegradation of norfloxacin

Ag3PO4/ZnO/C photocatalyst with p-n heterojunction has been prepared by ultrasound assisted precipitation based on ZnO/C obtained by pyrolysis using isoreticular metal-organic frameworks (IRMOF) as precursor. The results show that Ag3PO4 uniformly dispersed on the pores and surface of the porous ZnO/C, and the whole catalyst is floss cake-like. ZnO/C and Ag3PO4 are successfully composited and possess good photocatalytic activity and stability. The degradation rate of norfloxacin by Ag3PO4/ZnO/C can reach 89.48% under the best reaction conditions, which is 2.97 times than that of pure Ag3PO4, and Ag3PO4/ZnO/C also shows better photocatalytic performance and reusing stability than Ag3PO4. The results of the active species capture experiment confirms that ⋅O2− and holes (h+) play major roles in the process of degrading norfloxacin by Ag3PO4/ZnO/C under visible light irradiation. The main reason for the enhanced photocatalytic activity and stability of Ag3PO4/ZnO/C is that the introduction of ZnO/C has widened the light adsorption range and reduced the solubility of Ag3PO4 in Ag3PO4/ZnO/C. At the same time, the excellent electron transfer capability of graphite in ZnO/C and the p-n heterojunction formed between Ag3PO4 and ZnO can promote the electrons migrating from Ag3PO4 to ZnO/C, effectively inhibiting the photocorrosion of Ag3PO4.

Hierarchical porous spinel nickel cobaltite nanoflakes anchored reduced graphene oxide nano-photocatalyst for efficient degradation of organic pollutants under natural sunlight

Hierarchical spinel NiCo 2 O 4 anchored with reduced graphene oxide (NiCO 2 O 4 -rGO) nanoflake composites was prepared by using a chemical route for a high-performance photocatalyst. X-ray diffractometry, field emission scanning electron microscopy and Fourier transform infrared spectroscopy were employed to study the structure, morphology and functional groups of the as-prepared NiCO 2 O 4 -rGO nanoflake composites. The UV–vis diffusive reflectance spectroscopy revealed the reduction of optical bandgap from 1.32 to 1.20 eV compared with pristine spinel NiCo 2 O 4 nanoflakes. NiCO 2 O 4 -rGO nanoflake composites exhibited improved photocatalytic efficiency when compared with that of pristine NiCo 2 O 4 nanoflakes. We verified that 100% degradation of MB in 40 min was observed under natural sunlight irradiation. The photocatalytic degradation efficiency was found to retain 97% of its original value after 6 cycles. The superior photocatalytic efficiency of NiCO 2 O 4 -rGO nanoflake composites over pristine NiCo 2 O 4 nanoflakes is attributed to not only its enhanced surface area providing more active sites for light adsorption but also a heterojunction created between rGO and NiCo 2 O 4 . Addition of rGO greatly improves charge separation efficiency hence decreasing electron hole pair recombination. Overall, this work revealed that synthesis of NiCo 2 O 4 -rGO nanoflake composites may be a promising candidate for the removal of inorganic pollutant from waste water at industrial level under natural sunlight irradiation.

SiOC and SiCN-based ceramic supports for catalysts and photocatalysts

Nowadays, most industrial chemical products employ catalysts as an essential step to synthesize many commodities. Inspired by catalytic processes, the discovery of Honda-Fujishima, reported by analogy with natural photosynthesis, boosted the overall scientific interest in photocatalysis. This area aims for feasible energy generation and pollutants abatement, looking for beyond the efficiency under UV light, new perspectives towards visible light through novel composites. Suspended catalysts are commonly used due to simplicity, primarily to demonstrate concepts in lab-scale research. However, working with suspensions is not technologically feasible, and immobilizing on supports avoids the toxicity associated with free catalysts and facilitates further separation processes. Thus, immobilized catalysts on tailor-made porous support form heterojunctions and profiles as a more practical approach to tackling these challenges. In addition, involving just stable semiconductors within the system enables applying catalytic systems in harsh environments. The polymer-derived ceramic (PDCs) route has been studied in another technological frontier, addressing several technical issues over the past 50 years, allowing for coatings, foams, and fibers with controlled morphology and good thermal-oxidative resistance. Those features make PDCs promising supports for catalyst immobilization, particularly, SiOC and SiCN-based ceramics. This work provides an overview of PDCs and their interactions with catalysts. The manufacture approaches, catalyst type, component interactions, thermal treatment effects, catalytic activity under visible light, and other outcome properties are reviewed. Moreover, the research landscape and current challenges on catalysts supported by PDCs are discussed. Finally, the gaps regarding processing optimization and perspectives for PDC-based materials applied in catalyst-assisted systems are highlighted. • The application range of porous SiOC and SiCN supports in catalyst-assisted reactions under harsh environments are pointed up • An in-depth overview of SiOC and SiCN-based ceramics as supports and their effect in catalysis and photocatalysis is presented • Manufacturing approaches, type of catalyst, and intrinsic parameters of the as-obtained composites are discussed • Photocatalytic activity aiming to extend to the visible light adsorption is compared between the systems • The mechanism behind the performance is discussed thoroughly

Improved nitrogen adsorption and visible-light-driven nitrogen oxidation activity of divacancies-engineered ZnS

Currently, nitrate production from nitrogen under mild conditions is highly desirable. In this work, visible-light-responsive ZnS with divacancies is obtained by a simple hydrothermal method. Under visible light irradiation, the average nitrate producing rate is 0.71 mg g-1h−1, which is higher than the most reported photocatalysts. It also shows good nitrate selectivity. The pothole morphology evidently increases the surface area of ZnS-A, favoring the adsorption and activation of N2. Divacancies significantly widen light adsorption range, strengthen interaction of nitrogen with photocatalyst and provide more adsorption sites. Meanwhile, influences of vacancies on adsorption and activation of nitrogen are investigated. Compared to Zn vacancy, the adsorption of nitrogen can be obviously enhanced by S vacancy, while it is boosted to the largest extent by divacancies. Besides, divacancies weaken the adsorption of H2O, inhibiting the competitive water splitting reaction. Finally, an oxidation mechanism is proposed to explain the generation of nitrate. This work suggests that divacancies engineering is an efficient strategy to make full use of solar energy.

Sulfur‐Deficient ZnIn2S4/Oxygen‐Deficient WO3 Hybrids with Carbon Layer Bridges as a Novel Photothermal/Photocatalytic Integrated System for Z‐Scheme Overall Water Splitting

AbstractAlthough photocatalytic overall water splitting is a potential technology for converting solar energy into chemical fuel, the widely reported solar‐to‐hydrogen efficiency is around 1%, indicating unsatisfactory photocatalytic performance. Here, a novel photocatalyst material is designed and a whole reaction system is constructed, resulting in an integrative photothermal–photocatalytic Z‐scheme overall water splitting reaction system. In terms of materials design, a novel sulfur‐deficient ZnIn2S4/oxygen‐deficient WO3 (ZIS–WO) hybrid with surface‐carbonized wood (C‐wood) is reported. The ZIS–WO hybrid with sulfur and oxygen vacancies promotes the adsorption of visible light and the separation of charge carriers. The conductive C‐wood is strategically used as an additional electron bridge to accelerate electron transfer. In terms of system construction, the C‐wood exploits the photothermal effect to change the solid/liquid/gas triphase system to a solid/gas biphase system by transforming liquid water into steam, which drastically restrains carrier recombination, and decreases the photocatalytic reaction barrier. The H2 and O2 production rates in the proposed system are approximately 169.2 and 82.5 µmol h–1 under air mass (AM) 1.5 light irradiation, and the corresponding solar‐to‐hydrogen efficiency is as high as 1.52%. The study from photocatalyst design to reaction system construct opens a new insight for versatile and high‐performance photocatalytic overall water splitting.

Flexible and double-layered photothermal material based on resorcinol-formaldehyde foam for solar assisted water desalination

Solar-assisted steam generation is considered as an environmental-friendly and feasible technology to effectively harvest solar energy, which has been widely in water purification, seawater desalination and steam sterilization. In this work, we demonstrated flexible and scalable double-layered photothermal material (named as ppy-RF) based on phenolic aldehyde foam and polypyrrole coating as a light adsorption layer for solar steam generation. The resulting ppy-RF foam possessed interpenetrated and macroporous network with high porosity (>86%), superhydrophilicity, low thermal conductivity (0.0396 W m-1 K-1) and almost 100% absorbance (500-2500 nm). These characteristics make ppy-RF foam rapid water transportation and steam generation with an energy conversion efficiency of 90% under solar illumination of 1 kW h-1. Furthermore, the ppy-RF foam exhibits outstanding salt-resistant performance and long-term stability for desalination even in high salinity brine (20 wt%). By combination of its porous, flexible and monolithic configuration obtained by a simple and scalable fabrication method with efficient solar-thermal conversion ability and salt-resistance, the ppy-RF foam shows great potential in the application of clean water production and brine desalination.

Utilization of illumination and thermal field in the preparation of jet–fuel components: The photothermic catalysis of Jatropha oil over the M/TiO2–HZSM–5

Under simultaneous illumination and heating, Jatropha oil was converted into jet–fuel components over modified catalysts. XRD, HRTEM, N2 adsorption–desorption, XRF, NH3/CO–NH3–TPD/CO–TPD, UV–Vis and TG–DTG–MS were employed to determine the surface morphology and acidic site content of the modified catalysts. Through the characterizations and experimental results, the band gap of the catalysts modified with titanium dioxide was found to be significantly reduced, which enhanced the visible light adsorption of the catalysts. Moreover, the catalyst loaded with Pt contained the highest amount of weakly acidic sites, which led to the highest conversion and selectivity for the Pt/TiO2–HZSM–5 catalyst at 100 °C and 0.4 MPa H2 pressure. In addition, the pathway of photocatalytic decarboxylation and catalytic cracking of Jatropha oil was found to involve a cascade reaction from fatty acid to Cn–1 alkane and eventually to cracking products.

Construction of novel MWCNTs/Bi4O5I2 nanosheets with enhanced adsorption and photocatalytic performance for the degradation of tetracycline: Efficiency, mechanism and regeneration

Bismuth oxyhalide-based photocatalysts with anisotropic sandwiched-structure present excellent photoactivity in water purification. However, rapid recombination of photogenerated charge carriers and regeneration are two significant challenges of bismuth-based photocatalyst. Herein, a novel multiwalled carbon nanotubes (MWCNTs)/Bi4O5I2 heterostructure with narrow band-gap and high reactive species (RSs) production capacity were firstly designed via interfacial amidation linkage. Photoelectrochemical analysis confirmed that the interfacial amidation linkage significantly boosted the surface charge effective transfer (45 times vs Bi4O5I2) and broadened the visible light adsorption (555 nm), resulting in the enhanced photocatalytic activity. As expected, the optimized MWCNTs/Bi4O5I2 photocatalyst exhibited remarkable adsorption and photocatalytic performance for Tetracycline (TC) degradation under visible light with respect to that of Bi4O5I2 (2.32 times). Radical trapping experiments and Electron spin resonance (ESR) results clarified that h+ and •O2− contributed 34.48% and 93.97% of TC photodegradation, respectively. Density Functional Theory (DFT) calculation including frontier electron densities (FEDs) and Fukui methods further revealed the possible attack sites of RSs for TC. More insights for the decrease of stability showed that main adsorption sites and iodine dissolution were considered to be the key parameters for application of MWCNTs/Bi4O5I2 photocatalyst. Afterwards, we firstly proposed a facile regeneration strategy to solve the deactivation of bismuth oxyhalide-based photocatalysts. This study provided a potential approach to design novel bismuth oxyhalide-based photocatalysts with the high efficiency and possibility of regeneration.

Tailoring the Structural and Electronic Properties of Graphene through Ion Implantation.

Ion implantation is a superior post-synthesis doping technique to tailor the structural properties of materials. Via density functional theory (DFT) calculation and ab-initio molecular dynamics simulations (AIMD) based on stochastic boundary conditions, we systematically investigate the implantation of low energy elements Ga/Ge/As into graphene as well as the electronic, optoelectronic and transport properties. It is found that a single incident Ga, Ge or As atom can substitute a carbon atom of graphene lattice due to the head-on collision as their initial kinetic energies lie in the ranges of 25–26 eV/atom, 22–33 eV/atom and 19–42 eV/atom, respectively. Owing to the different chemical interactions between incident atom and graphene lattice, Ge and As atoms have a wide kinetic energy window for implantation, while Ga is not. Moreover, implantation of Ga/Ge/As into graphene opens up a concentration-dependent bandgap from ~0.1 to ~0.6 eV, enhancing the green and blue light adsorption through optical analysis. Furthermore, the carrier mobility of ion-implanted graphene is lower than pristine graphene; however, it is still almost one order of magnitude higher than silicon semiconductors. These results provide useful guidance for the fabrication of electronic and optoelectronic devices of single-atom-thick two-dimensional materials through the ion implantation technique.

Ethanol-assisted molten salt synthesis of Bi4Ti3O12/Bi2Ti2O7 with enhanced visible light photocatalytic performance

Molten salt synthesis is an efficient method for preparation of photocatalyst. Enhancing precursor mixing effect is important. In this study, we found ethanol is important for synthsis of face-to-face type Bi4Ti3O12/Bi2Ti2O7 composite photocatalyst. The prepared Bi4Ti3O12/Bi2Ti2O7 (B3) composite under molar ratio of Bi:Ti of 4:3.6 displays higher photocatalytic activity compared with Bi4Ti3O12 (B1) and Bi2Ti2O7 (B4). The photocurrent density of B3 is 2 times higher than B1 and 1.6 times higher than B4, and B3 has smallest charge resistance between sample and solution. Combined with XPS, the study found that the higher photocatalytic activity origins from large charge transfer interface and built-in electric field (BIEF) around such interface, rathor than light absorption and dark adsorption.

NIR light responsive MoS2 nanomaterials for rapid sterilization: Optimum photothermal effect via sulfur vacancy modulation

As the increasing problem of bacterial resistance has become the threaten to human health and environmental protection, the explorations of efficient and environmental-friendly antimicrobial agents are highly desired. Recently, vacancy engineering is regarded as the quite novel strategy to regulate the electronic structure of semiconductor Nanomaterials (NMs), largely improving their photocatalytic performance in rapid and safe sterilization. In this study, molybdenumsulfide(MoS2) NMs with different concentrations of sulfur vacancies (Vs) were synthesized through annealed at different temperature (i.e., 150 °C, 250 °C and 350 °C), providing the platform for studying the efficient bacterial inactivation of defective MoS2 NMs under the near-infrared light irradiation. The optimum photothermal conversion efficiency could be achieved with the appropriate concentration of Vs, through improving the light adsorption and preventing the recombination of photogenerated e−/h+ pairs. In addition, MoS2 NMs with the abundant Vs exhibited hyperthermia and strong binding ability to bacteria, leading to the severe damage to cell wall integrity, energy supply and antioxidant system. Collectively, these results focused on the relationship between optimum antibacterial efficiency and appropriate concentrations of Vs, providing new insights into the designation of photocatalysts with highly efficient sterilization.

Confined conductive and light-adsorbed network in metal organic frameworks (MIL-88B(Fe)) with enhanced photo-Fenton catalytic activity for sulfamethoxazole degradation

High light adsorption and fast charge separation are crucial for photo-Fenton catalytic activity of MOFs. Herein, bottom-up design was proposed to fabricate polypyrrole (PPyC) nanowires in MIL-88B(Fe) cages as photo-Fenton catalyst for Sulfamethoxazole (SMX) efficient degradation. Pyrrole was prior anchored into MIL-88B(Fe) cluster via Fe-N coordination, and then the additional monomer pyrrole was further triggered bottom-up polymerization in confined cages of MIL-88B(Fe) and formed PPyC@Py-MIL(Fe) composite. These PPyC nanowires were dispersed in Py-MIL(Fe) cages and tightly connected with MOFs clusters via Fe-N bonding. Characterization proved that: (1) Interfacial Fe-N can significantly promote the efficient electron transport from PPyC nanowires to Py-MIL(Fe), enhance optical absorption property, and construct strong Lewis acidic sites and ligand vacancies in PPyC@Py-MIL(Fe). (2) The confined PPyC nanowire via Fe-N connection remarkably promote photo-generated electron-hole separation, Fe2+|Fe3+ redox ability of MOF, and improved photo-electric corrosion ability. As a result, it significantly enhanced the photo-Fenton catalytic performance for SMX degradation. Catalytic oxidation was attributed to the generation of ‧OH species that oxidized 93% SMX in 60 min, showing ultra-rapid degradation and TOC removal rates of 33.7 min−1·mg·g−1 and 8.68 min−1·mg·g−1 respectively, which was about 4–220 times higher than those reported state-of-the-art catalysts. Additionally, the PPyC@Py-MIL(Fe) catalyst showed minimal loss in catalytic activity even after recycling for 10 times, exhibiting good recycling stability compared to many MOFs. Systematic analysis shown that in-situ anchored growth of polypyrrole in confined porous cages of MOF can effectively enhance the catalytic activity and stability of MIL-88B(Fe), and has great development potential applications for photo-Fenton catalytic degradation of organic pollutants.