Abundant Surface Hydroxyl Research Articles

Surface modification of (001) facets dominated TiO2 with ozone for adsorption and photocatalytic degradation of gaseous toluene

This study investigated the positive effect of surface modification with ozone on the photo-catalytic performance of anatase TiO2 with dominated (001) facets for toluene degradation. The performance of photocatalyst was tested on a home-made volatile organic compounds degradation system. The ozone modification, toluene adsorption and degradation mechanism were established by a combination of various characterization methods, in situ diffuse reflectance infrared fourier transform spectroscopy, and density functional theory calculation. The surface modification with ozone can significantly enhance the photocatalytic degradation performance for toluene. The abundant unsaturated coordinated 5c-Ti sites on (001) facets act as the adsorption sites for ozone. The formed Ti–O bonds reacted with H2O to generate a large amount of isolated Ti5c-OH which act as the adsorption sites for toluene, and thus significantly increase the adsorption capacity for toluene. The outstanding photo-catalytic performance of ozone-modified TiO2 is due to its high adsorption ability for toluene and the abundant surface hydroxyl groups, which produce very reactive OH· radicals under irradiation. Furthermore, the O2 generated via ozone dissociation could combine with the photogenerated electrons to form superoxide radicals which are also conductive to the toluene degradation.

Constructing mesoporous phosphated titanium oxide for efficient Cr(III) removal

Heavy metal removal by environmental-friendly nanostructured TiO2 adsorbent is a promising strategy to facilitate wastewater treatment. Here, a boiling water synthetic approach is explored to prepare mesoporous phosphated TiO2 (PTO) used for Cr(III) adsorption in polluted water. We obtain mesoporous 8-PTO (synthesized with 8% molar ratio of H3PO4) with a high specific surface area (278 m2/g), narrow size distribution (<5 nm), low pHzpc (pH of zero point of charge) value (∼1.0), and abundant surface hydroxyl group, which is attributed to the introduction of H3PO4 during the hydrolysis process of TiCl4 in boiling water. Importantly, the obtained 8-PTO shows better thermal stability than pure TiO2 and retains mesoporous structure after thermal treatment owning to [PO4] tetrahedral incorporated into the network of [TiO6] octahedral. The optimized 8-PTO exhibits superior Cr(III) adsorption up to 92 mg/g in sewage, which makes it one of the best materials among TiO2 adsorbent known for Cr(III) Removal (10–83 mg/g). Additionally, the as-prepared mesoporous 8-PTO adsorbent possesses an excellent reusability without significant degradation and can largely avoid the generation of secondary contaminants. A linear relationship (R2 = 0.9985) between adsorption capacity and hydroxyl content percentage of different PTO samples is revealed, indicating that the surface hydroxyl groups play a decisive role in the adsorption process. This study provides a facile approach to synthesize high specific surface area mesoporous phosphated TiO2 with rich surface functional groups for efficient Cr(III) removal in sewage.

A promising visible-light photocatalyst: H2 plasma-activated amorphous-TiO2-supported Au nanoparticles

Functionalized amorphous TiO2 (AmT) with high surface area and abundant surface hydroxyl groups could be a promising support for plasmonic Au/TiO2 nanocatalysts. To overcome the limitations of conventional heat treatment on plasmonic Au/AmT nanocatalysts, cold hydrogen (H2) plasma activation is employed and makes it possible to achieve superior visible-light (VL) photocatalytic activity and durability. Catalyst characterization results suggest that H2 plasma can activate Au/AmT nanocatalysts to form high levels of metallic Au with strong surface plasmon resonance, low charge transfer resistance, and a unique interface between Au nanoparticles and AmT support. Comparative study of Au/AmT and Au/P25 (Degussa TiO2) activated by different plasmas (H2 or O2) reveals that the excellent performance of H2 plasma in Au/AmT activation originates from strong interaction between surface hydroxyl groups and Au precursors. This work offers the potential for preparing VL photocatalytic Au/AmT films on flexible substrates for extensive applications in photocatalysis and solar cells.

Facile synthesis of alkaline-earth metal manganites for the efficient degradation of phenolic compounds via catalytic ozonation and evaluation of the reaction mechanism

In this paper, we demonstrate the facile and general synthesis of alkaline-earth metal manganites, denoted as A(Mg, Ca, Ba)MnxOy, for efficient degradation of high-concentration phenolic compounds via catalytic ozonation. The representative CaMnxOy oxides show a hierarchical spherical structure constructed by crystalline nanorods and numerous macropores. They possess mixed Mn4+/Mn3+ chemical valences and abundant surface hydroxyl (OH) groups. The ozone (O3) decomposition rate on the CaMnxOy catalysts is greatly accelerated and follows the first-order law. These catalysts are promising for the degradation of phenolic compounds via catalytic ozonation, exhibiting rapid pseudofirst-order degradation kinetics, a high total organic carbon (TOC) removal efficiency and an excellent stability. Under optimized conditions (a low O3 dosage of 1.5 mg/min and a catalyst dosage of 7.5 g/L), for the treatment of concentrated phenol (50–240 mg/L), the CaMnxOy catalysts show 100% degradation and 50–70% mineralization within 1.0 h. The Ca2+ ions are essential to create redox Mn4+/Mn3+ couples and to significantly reduce manganese leaching. High surface ratios of Mn4+/Mn3+ and OH/lattice oxygen (Olat) are beneficial for enhancing the catalytic performance. Superoxide anion free radicals (O2–) and singlet oxygen (1O2) are the predominant reactive species for the oxidation degradation. The O2– reaction pathway is proposed. Specifically, the surface OH sites activate O3, displaying highly enhanced decomposition rates. The generated O2– and 1O2 play a role in oxidation. The redox Mn4+/Mn3+ and the Olat/oxygen vacancy (Olat/Ovac) couples play important roles in electron transfer. The proposed mechanism is supported by active site probing, radical scavenging, spectroscopic studies, and the results in the degradation of substituted phenols.

Metal ion adsorption from wastewater by g-C3N4 modified with hydroxyapatite: a case study from Sarcheshmeh Acid Mine Drainage

Hydroxyapatite (Hap) modified graphitic carbon nitride (g-C3N4) powders (Hap/g-C3N4) were prepared and characterized. The sorption activities of g-C3N4 and Hap/g-C3N4 were evaluated for the removal of Cu2+, Mn2+, Zn2+, Pb2+, Fe3+ and Cd2+ metal ions from simulated wastewater (synthetic solutions containing metal ions) and acid mine drainage from the sSarcheshmeh Copper Mine. The results indicated that the sorption capacities (SC) of g-C3N4 remarkably increased after the modification by Hap. Hap/g-C3N4 possessed higher SC than unmodified g-C3N4. So, the sorption mechanisms appear mainly attributable to the chemical interactions between the metal ions and functional groups on the Hap/g-C3N4 surface. More adsorption sites were formed on Hap/g-C3N4, which possessed abundant surface hydroxyl, phosphate and –NH2/–NH–/=N groups causing the higher efficiency of metal ion uptakes. Divalent metal cations are first adsorbed on the Hap/g-C3N4 surface and then substitution with Ca2+ ion can occur. Effect of pH evaluations confirmed that SC increased steeply with the pH increasing on both g-C3N4 and Hap/g-C3N4 adsorbents. The kinetic study demonstrated that the adsorption data were correlated well with the Langmuir isotherm model, and the adsorption process successfully followed the pseudo-second-order model.

Transport of graphene oxide in saturated quartz sand containing iron oxides

The environmental implications of graphene oxide (GO) have received much attention. Transport of GO in subsurface environment is a critical process affecting the migration and potential risks of this important class of carbonaceous nanomaterials. To date, the effects of heterogeneity in porous media, in particular, iron oxides, on GO transport are not well studied. In this study, we investigated the transport properties of GO in saturate quartz sand as affected by the presence of iron oxides, using goethite, hematite and ferrihydrite as the model iron oxide species, and applied a two-site transport model (which accounts for both attachment and straining) to fit the transport data. We found that iron oxide coating on sand surfaces markedly inhibited GO transport, mainly due to increased electrostatic attraction between particles and collectors, as the positively charged iron oxides provided favorable deposition sites for the negatively charged GO nanosheets. Additionally, increased surface roughness was likely an additional mechanism leading to the enhanced GO deposition. The extent of transport inhibition by iron oxides also depended on the morphology iron oxides, in that at the same Fe loading a larger effect was observed when iron oxides existed as the coating on sand surface than as discreet particles. The presence of iron oxide coatings (tested using goethite) could magnify the effects of cations on GO transport. Specifically, the presence of goethite facilitated the accumulation of cations on the surface of sand, and in the case of Ca2+, the binding of GO via the cation-bridging mechanism was enhanced, as goethite contained abundant surface hydroxyl groups that are strong metal-complexing moieties.

Impact of Zr-Doped TiO2 Photocatalyst on Formaldehyde Degradation by Na Addition

In this study, a series of Na–Zr/TiO2 photocatalysts with different Na contents were synthesized via the sol–gel process. The characterization of the materials showed that Na addition facilitates the maintenance of anatase and excess Na led to particle size increases because of the formation of Na2Ti3O7. The XPS results suggested that Na loading can increase the number of oxygen vacancies, leading to more abundant surface hydroxyl groups. The enhanced photocatalytic activities under visible light irradiation can be attributed to a decreasing band gap and increasing oxygen vacancies. The efficiency of the Na–Zr/TiO2 samples was investigated by the degradation of formaldehyde under visible light. A high degradation rate of formaldehyde of approximately 96.6% was obtained with 2.5 mol % Na added to the Zr/TiO2 samples.

Effect of Temperature on Thermal Treatment of Silica Coated Magnetic Nanoparticles

In the quest for developing a catalyst with as many desired characteristics, a facile synthetic route was designed for the preparation of mesoporous silica coated magnetic nanoparticles(MSMNP) employing a colloid mill reactor. The composite particles were characterized by the techniques, such as nitrogen adsorption-desorption isotherms, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction patterns (XRD), thermo-gravimetric analysis(TGA), Fourier transform infrared spectroscopy(FTIR) and vibrating sample magnetometer(VSM), etc. The analysis showed that the resulted MSMNP composites were composed of silica shell layers with open pores connecting channels and NiFe2O4 with spinel structure, so the thermal treatment temperature did not show significant effect on pore textural properties, and its specific surface areas were in the range of 443–474 m2/g, while pore volume of about 0.8 cm3/g with an average pore size of around 9.5 nm. The composites with super paramagnetic nature were encapsulated entirely with amorphous silica layers contributing to optimum porosity and abundant surface hydroxyl groups.

Low temperature SCR reaction over Nano-Structured Fe-Mn Oxides: Characterization, performance, and kinetic study

Fe-Mn oxides was prepared by thermal activation of Mn-rich limonite at different temperatures, and then developed as catalysts for low-temperature NH3-SCR. The obtained samples were characterized by XRD, XRF, TEM, XPS, BET, H2-TPR, NH3-TPD, NH3-SCR model reaction and in situ DRIFTS. The results indicated that Fe-Mn oxides catalyst derived from the thermal treatment at 300 °C (H300) exhibited an excellent NO conversion which was higher than 90% at a temperature range from 130 to 300 °C. The large surface area (95.9 m2/g), large amount of acid sites, suitable reduction behavior, and abundant surface hydroxyl positively responsed to the excellent performance of H300 for NH3-SCR. The results of in situ DRIFTS and kinetic study demonstrated that when the SCR reaction temperature reached to 100 °C, both the Eley–Rideal mechanism and the Langmuir-Hinshelwood mechanism might happen over H300. However, the Langmuir-Hinshelwood mechanism could be approximately neglected at higher reaction temperatures. This study favors the understanding of NH3-SCR mechanism of the prepared provides Fe-Mn oxides and explores new application field for Mn-rich limonite in low-temperature NH3-SCR.

Advanced Materials through Assembly of Nanocelluloses

There is an emerging quest for lightweight materials with excellent mechanical properties and economic production, while still being sustainable and functionalizable. They could form the basis of the future bioeconomy for energy and material efficiency. Cellulose has long been recognized as an abundant polymer. Modified celluloses were, in fact, among the first polymers used in technical applications; however, they were later replaced by petroleum-based synthetic polymers. Currently, there is a resurgence of interest to utilize renewable resources, where cellulose is foreseen to make again a major impact, this time in the development of advanced materials. This is because of its availability and properties, as well as economic and sustainable production. Among cellulose-based structures, cellulose nanofibrils and nanocrystals display nanoscale lateral dimensions and lengths ranging from nanometers to micrometers. Their excellent mechanical properties are, in part, due to their crystalline assembly via hydrogen bonds. Owing to their abundant surface hydroxyl groups, they can be easily modified with nanoparticles, (bio)polymers, inorganics, or nanocarbons to form functional fibers, films, bulk matter, and porous aerogels and foams. Here, some of the recent progress in the development of advanced materials within this rapidly growing field is reviewed.

Ni and Cu ion-exchanged nanostructured mesoporous zeolite: A noble metal free, efficient, and durable electrocatalyst for alkaline methanol oxidation reaction

The direct methanol fuel cell (DMFC) is considered as one of the promising power hubs to ensure the future global energy demand. The development of an efficient and cost-effective electrocatalyst for methanol electrooxidation (MEO) is one of the keys to make DMFC viable for practical application. Herein, an effort has been made to design a low-cost, noble metal free MEO catalyst. The electrocatalyst is synthesized by a facile ion-exchange of mesoporous zeolite ZSM-5 (Zeolite Socony Mobil 5) with non-precious Ni2+ and Cu2+ ions. The detailed electrocatalytic investigations reveal that the optimum contents of Ni2+ and Cu2+ ions in ion-exchanged mesoporous ZSM-5 (Ni2Cu1-MesoZ) are required to exhibit the best electrocatalytic activity (current density and onset potential). Moreover, the MEO capacity of the developed catalyst is found to be comparatively higher than the state-of-art Pt (20%)/C catalyst. The present electrocatalyst retains the catalytic current density even after 1000 cycles of a test run without any micro-structural change. The high surface area, Brönsted acidity, abundant surface hydroxyl groups, inter-crystalline mesoporosity, effective & optimum incorporation of Ni2+/Cu2+ species in the zeolite matrix provide highly dispersed electroactive sites and fast analyte diffusion resulting in a noteworthy MEO kinetics. The CO-stripping analysis also indicates that Ni2Cu1-MesoZ has a high tolerance to CO poisoning which is one of the prime reasons for high MEO activity. The underlying results demonstrate that the impressive electrocatalytic activity and high stability of Ni2+-Cu2+ ion-exchanged mesoporous ZSM-5 would be an interesting electrode material for the commercial methanol fuel cell application. Most importantly, the present study will open up a new avenue in the MEO electrocatalyst development due to its ease of synthesis, scale-up, fabrication, stability/durability, and efficient electrocatalytic activity for alkaline direct methanol fuel cell.

Study on the enhanced adsorption properties of lysozyme on polyacrylic acid modified TiO2 nano-adsorbents

The adsorption and immobilization of enzymes onto solid carriers has been focused on due to their many advantages, such as improved stability against a thermal or organic solvent and a good cycle usability. TiO2 nanoparticles is one of excellent nano-adsorbents owing to its excellent biocompatibility, non-inflammatory, and abundant surface hydroxyl groups, which are convenient to be combined with various functional groups. In this paper polyacrylic acid (PAA) modified TiO2 nanoparticles were synthesized through an in situ light-induced polymerization of acrylic acid on the surface of TiO2 nanoparticles. The structure and surface physicochemical properties of the PAA/TiO2 nanoparticles were characterized by TEM, XRD, FT-IR, Zeta potential measurements and TG-DSC. The experimental results showed that the isoelectric point of PAA/TiO2 significantly reduced to 1.82 compared with that of pure TiO2 nanoparticles (6.08). In the adsorption tests of lysozyme (Lyz), the PAA/TiO2 nanoparticles displayed enhanced adsorption activity compared with pristine TiO2. The maximum adsorption capacity of PAA/TiO2 for Lyz was 225.9 mg g−1 under the optimum conditions where the initial concentration of Lyz was 300 mg ml−1, the addition amount of PAA/TiO2 was 6.4 mg, the adsorption time was 30 min and the pH value was 7.0. The sodium dodecyl sulfate (SDS, 0.5%) presented the best efficiency (76.86%) in the removal of adsorbed Lyz, and the PAA/TiO2 nanoparticles showed excellent adsorption stability based on five cyclic adsorption–desorption tests. The fitting calculation results of the adsorption isotherm and the thermodynamics indicated the adsorption was an exothermic, entropy increasing, spontaneous and monomolecular layer adsorption process.

Defective magnesium ferrite nano-platelets for the adsorption of As(V): The role of surface hydroxyl groups.

In this work, magnesium ferrite (MgFe2O4) nano-platelets with rich defects and abundant surface hydroxyl groups were synthesized, and used for the removal of low concentration As(V) in aqueous solution. Results from scanning electron microscopy (SEM) showed that the as-synthesized MgFe2O4 nano-platelets were consisted of many individual nanospheres. Rietveld refinement of X-ray diffraction (XRD) data indicated that the Mg2+ ions substituted the Fe3+ ions at both the octahedral and the tetrahedral sites of the crystal structure. Batch adsorption experiment showed that the equilibrium concentration of As(V) could be reduced down to 4.9 μg·L-1 when the initial concentration of As(V) is 1 mg·L-1, which complied with the drinking water standard of WHO (10 μg·L-1). The adsorption capacity of synthesized MgFe2O4 towards As(V) was higher than commonly used iron oxide adsorbents (Fe3O4, γ-Fe2O3 and α-Fe2O3). Mechanistic studies proved that the superior adsorption capacity was attributed to: (1) increased amount of surface hydroxyl groups that resulted from the surface defects. (2) formation of tridentate hexanuclear surface complexes instead of bidentate binuclear complexes, and (3) formation of excess Mg-OH surface hydroxyl groups and As-Mg monodentate mononuclear surface complexes. This work disclosed the correlation of the superior As(V) adsorption ability with the surface hydroxyl groups in defective MgFe2O4, and propose MgFe2O4 as a potential candidate for the remediation of As-contaminated water.

Metal organic framework-derived CoMn2O4 catalyst for heterogeneous activation of peroxymonosulfate and sulfanilamide degradation

Spinel-type CoMn2O4 materials are promising catalyst for heterogeneous activation of peroxymonosulfate (PMS), but the catalytic activity still need considerable improvements for practical environmental application and the underlying Co-Mn synergy is unclear. In this work, we synthesized CoMn2O4 microplates by using CoMn2-perylene-3,4,9,10-tetracarboxylic dianhydride (ptcda) metal organic frameworks (MOFs) as the precursor. The resulting material showed significantly higher catalytic activity for the PMS activation and sulfanilamide (SA) degradation than the CoMn2O4 obtained by conventional solvothermal synthesis methods, due to its much higher specific surface area and abundant surface hydroxyl groups as the active sites. In addition, the Co-Mn synergy in the synthesized material for the efficient heterogeneous catalysis was elucidated. The catalyst stability was also evaluated. Our work may lay the foundation for optimized design of highly-efficient heterogeneous catalyst for environmental application.

Titania nanowires functionalized polyester fabrics with enhanced photocatalytic and antibacterial performances

Flexible organic fabrics coated with titania find wide applications in pollutant degradations and antibiosis. Because of the enhanced charge separations, TiO2 with one-dimensional nanostructures exhibits photocatalytic activity superior to that of nanoparticulate films; however, only the later has been achieved on organic substrates through commonly sol-gel techniques till now. In this study, radially aligned TiO2 nanowires were precipitated on polyester fabrics through multi-steps of surface roughening, sol-gel TiO2 seeding, hydrogen titanate nanobelts precipitation, and finally sulfuric acid treatment. Both mesoporous anatase TiO2 nanowires and single-crystalline rutile TiO2 nanorods have been achieved, which, together with some unchanged titanate nanobelts, exhibited an overall narrowed band gap of ca. 2.50eV. The TiO2 nanowires on flexible PET fabrics showed higher photocatalytic activity towards degradations of not only rhodamine B in water but also toluene gas in air under UV light illumination, when compared with either TiO2 nanotube array or commercial Degussa P25 nanoparticulate films on metallic Ti substrates. Remarkable sterilization of E. coli and S. epidermidis under visible light irradiation was also achieved. The excellent photocatalytic and antibacterial performances were attributed to the unique mixed 1D nanostructures, phase junctions, abundant surface hydroxyl groups, and the narrowed band gap.

Low temperature synthesis of few-layer titanate nanobelts on Ti mesh and the hot-water induced transformations to highly photocatalytic active titania nanorods

An efficient photocatalytic reactor to remove pollutants from either water or air relies on highly active photocatalytic thin films on appropriate substrates, which contribute to both light harvesting and pollutant molecules transfer. In this investigation, few-layer titanate nanobelts were deposited on metallic Ti mesh using hydrogen peroxide solution, which were then subjected to a subsequent hot water treatment to achieve crystallized titania nanorod arrays. The three-dimensional arrays of nanorods formed on Ti mesh (three layers overlapped) exhibited an exceptional high efficiency when utilized to assist photodegradation of rhodamine B in water under UV light illumination, which is 25 times that of P25 film, and even 1.3 times that of P25 nanoparticles in a slurry system. For photodegradation of phenol in water, the three-layer Ti mesh also exhibited a reaction rate constant 6.9 times that of P25 film. The reduced band gap, abundant surface hydroxyl groups, and mixed phase effects arising from the low temperature approach contribute to the high photocatalytic activity.

Anchoring 20(R)-Ginsenoside Rg3 onto Cellulose Nanocrystals To Increase the Hydroxyl Radical Scavenging Activity

Cellulose nanocrystals (CNCs) exhibit attractive properties as carriers for bioactive molecules, including their large surface area, charge characteristics, and abundant surface hydroxyl groups, among others. In this study, we used CNCs as carriers for a hydrophobic drug, 20(R)-ginsenoside Rg3 (here abbreviated as 20(R)-Rg3), to improve its bioavailability, dispersity, and antioxidation activity in an aqueous system. The CNC/20(R)-Rg3 nanocomposites were fabricated and then characterized by transmission electron microscopy, Fourier transform IR spectroscopy, and X-ray diffraction. The particle size of 20(R)-Rg3 was in the range of 8–22 nm. In vitro hydroxyl radical scavenging by the 2-deoxyribose oxidation method and the salicylic acid hydroxylation method showed that the CNC/20(R)-Rg3 nanocomposites had much higher antioxidation activity (33.58% and 48.62%) than CNC-free 20(R)-Rg3, water-dispersed 20(R)-Rg3, and CNCs.

Room‐Temperature Hydrolysis of Potassium Titanyl Oxalate and Water‐Assisted Crystallization for TiO2 with High Photocatalytic Activity

AbstractThe commonly adopted approach to synthesize nanostructured TiO2 starting from titanates demands a hydrothermal environment to achieve the titanate precursor, and a subsequent high temperature calcination to fulfill the decomposition of titanates and crystallization of TiO2. In this report, hydrogen titanate aggregates were achieved by a room‐temperature hydrolysis of a potassium titanyl oxalate in an aqueous H2O2 solution. The subsequent immersion in water at 80 °C induced the crystallization of TiO2 with a mixture of anatase nanoparticles and rutile nanorods. The anatase fraction increased with increasing immersing duration in hot water for up to 72 h. The low‐temperature crystallized TiO2 powders possessed abundant surface hydroxyl groups (∼38 %), high specific surface area (∼126 m2/g) and pore volume (∼0.50 cm3/g). When utilized to assist photodegradation of rhodamine B in water under UV light illumination, the reaction rate constant was twice that of the commercial P25 TiO2 nanoparticles. The high photocatalytic activity is contributed to the abundant surface hydroxyl groups, high specific surface area, and the appropriate mixture of anatase nanoparticles and rutile nanorods (∼84:16 in weight).

Markedly Enhanced Surface Hydroxyl Groups of TiO₂ Nanoparticles with Superior Water-Dispersibility for Photocatalysis.

The benefits of increasing the number of surface hydroxyls on TiO2 nanoparticles (NPs) are known for environmental and energy applications; however, the roles of the hydroxyl groups have not been characterized and distinguished. Herein, TiO2 NPs with abundant surface hydroxyl groups were prepared using commercial titanium dioxide (ST-01) powder pretreated with alkaline hydrogen peroxide. Through this simple treatment, the pure anatase phase was retained with an average crystallite size of 5 nm and the surface hydroxyl group density was enhanced to 12.0 OH/nm2, estimated by thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Especially, this treatment increased the amounts of terminal hydroxyls five- to six-fold, which could raise the isoelectric point and the positive charges on the TiO2 surface in water. The photocatalytic efficiency of the obtained TiO2 NPs was investigated by the photodegradation of sulforhodamine B under visible light irradiation as a function of TiO2 content, pH of solution, and initial dye concentration. The high surface hydroxyl group density of TiO2 NPs can not only enhance water-dispersibility but also promote dye sensitization by generating more hydroxyl radicals.

Facile Preparation of a Stable Fe3O4@LDH@NiB Magnetic Core‐Shell Nanocomposite for Hydrogenation

AbstractA novel NiB deposited layered double hydroxide (LDH) coated ferroferric oxide (Fe3O4@LDH@NiB) magnetic core‐shell nanocomposite was successfully fabricated by the combination of coprecipitation and impregnation‐reduction. During the Fe3O4@LDH preparation, a facile template‐free approach was employed to introduce the LDH shell, which was more efficient than the conventional method for the preparation of mesoporous materials that always needs to introduce and remove templates. The resulted Fe3O4@LDH has a relatively high surface area and abundant surface hydroxyl group, which can adsorb metal ions, making it favorable to disperse and stabilize the active Ni species, as demonstraed by TEM, XPS, FT‐IR and BET characterizations. Therefore, it exhibited good activity in the selective hydrogenation of cinnamic acid to hydrocinnamic acid with the conversion and selectivity both approaching to 100%. Notably, the obtained Fe3O4@LDH@NiB can be easily separated by an external magnetic field and recycled eleven times without appreciable loss of its initial catalytic activity.