Novel porous magadiite/Al-magadiite heterostructures (PMH/PAMH) and aluminated derivatives of PMH (xAl-PMH, x = Al/Si in feeding) were fabricated upon two-dimensional interlayer cosurfactant-directing TEOS hydrolysis–condensation–polymerization from synthetic Na-magadiite/Na-[Al]magadiite and postgrafting of Al into the interlayer silica framework of PMH from NaAlO2 precursor, respectively. Characterization studies indicate that PMH and PAMH possess high surface area (SA), high thermal stability, and unique supermicro–mesoporous structure upon effective assembly of interlayer mesostructured silica and clay layers but weak Lewis acidity. The xAl-PMH (x = 0.2, 0.4) samples show successful incorporation of Al into interlayer mesostructure of PMH mainly in tetra-coordinated form, leading to greatly increased Lewis acidity and newly created Brønsted acidity together with well-kept layered supermicro-mesoporous porosity and reduced SA (>280 m2/g) while 0.6Al-PMH shows collapsed layers. 0.4Al-PMH exhibits the highest liquid-phase Friedel–Crafts tert-butylation activity of catechol with 93.4% conversion and 80.4% 4-tert-butylcatechol selectivity due to the strongest synergy between the surface acidity and supermicro–mesostructure.

A series of novel hierarchical nanocomposite catalysts xCu@Cu2O/MgAlO-rGO were fabricated by calcination of CuxMg3−xAl-LDH/rGO precursors (LDH: layered double hydroxide, rGO: reduced graphene oxide, and x = 0.5, 1.0, and 1.5), obtained by a facile citric acid-assisted coprecipitation route, under a N2 flow upon in situ self-reduction of lattice atomic-dispersed Cu2+ by rGO. Systematic characterization reveals highly dispersed core–shell-like Cu@Cu2O nanoparticles near the border between vertically interconnected mixed oxide MgAlO nanoplates and rGO layers. All the obtained catalysts show extraordinary catalytic performances for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at room temperature. The 1.0Cu@Cu2O/MgAlO-rGO shows the highest activity for complete conversion of 4-NP with an apparent rate constant (kapp) of 55.3 × 10−3 s−1, a normalized rate constant (knor) of 14 497 s−1 g−1 on an active Cu content, and an unprecedented recycling stability for 25 successive cycles, which are superior to those of the recently reported Cu- and Co-based metal nanoparticles and even compared favourably with those of the most active noble metal catalysts. The superior activity of 1.0Cu@Cu2O/MgAlO-rGO can be attributed to the highly dispersed core–shell-like Cu@Cu2O nanoparticles and the greatly enhanced four-phase synergistic effect among Cu, Cu2O, MgAlO and rGO upon calcination. Moreover, 1.0Cu@Cu2O/MgAlO-rGO shows an excellent efficiency in the fixed bed system for the treatment of simulated industrial effluents containing nitrophenols and organic dyes. The present cost-effective, highly efficient and reusable non-noble metal nanocatalyst would open a new pathway for future water remediation.

A series of nickel-based layered double hydroxides supported nearly atomic precise Au25 nanoclusters catalysts, and especially Au25/NixAl-LDH systems (x = Ni/Al, 2, 3, 4) were fabricated via modified electrostatic adsorption of captopril-capped clusters Au25Capt18 onto the predispersed positively-charged NixAl-LDH supports followed by proper calcination. Detailed characterizations show that the ultrafine gold clusters of ∼0.9 nm were well dispersed on the edge sites of hexagonal plate-like particles of NixAl-LDH (x = 2, 3) originated from their ordered LDH layers with more Ni–OH sites and strong Au–LDH synergy, while slightly aggregated to ∼1.1 nm on the irregular Ni4Al-LDH due to its poor layer structure along with doped nickel oxide. The catalysts exhibit excellent activity for selective oxidation of 1-phenylethanol to acetophenone with molecular oxygen under base-free, and the activity follows an increased order of Au25/Ni4Al-LDH < Au25/Ni2Al-LDH < Au25/Ni3Al-LDH. The Au25/Ni3Al-LDH shows the highest activity with TOF of 6780 h−1 in toluene and 118500 h−1 in solvent-free and can be applied for a wide range of alcohols, mainly ascribed to ultrafine gold clusters and strongest gold–LDH interaction associated with the highly ordered Ni3Al-LDH layers. Similar regularity is found in the Au25/NixMn-LDH and Au25/Ni3−xMnxFe-LDH systems. The Au25/Ni3Al-LDH can be reused 5 times without loss of activity. The least-squares fit analysis yields the rate constant (k) and apparent activation energy (Ea) of Au25/NixAl-LDH catalysts for 1-phenylethanol oxidation, and the order of k and Ea values act in accordance with their reactivities.

A facile template-free solvothermal method without any additional alkali was developed to fabricate a 3D hierarchical hollow microsphere precursor, followed by annealing in air, leading to a novel 3D hierarchical NiCo2O4 hollow microsphere material, which is composed of mesoporous (16.1 nm) ultrathin nanosheets (∼11–21 nm) consisting of ultrafine NiCo2O4 nanoparticles (11.9 nm). This 3D hierarchical NiCo2O4 nanosheet hollow microsphere material possesses a high specific surface area (93.4 m2 g−1) and mesoporosity, and thus superior electrochemical performance as an advanced electrode material. For methanol electrooxidation, the 3D hierarchical NiCo2O4 nanosheet hollow microsphere displays much higher electrocatalytic activity (95 A g−1, at 0.6 V), lower overpotential (0.27 V, vs. SCE), and higher stability compared with the 3D hierarchical NiCo2O4 nanosheet solid microspheres, Co3O4 and NiO microspheres. For supercapacitors, the NiCo2O4 hollow microsphere exhibits excellent specific capacitance of 1701 F g−1 at 1 A g−1, excellent rate capability (61.5% retention at 15 A g−1), and good electrochemical stability with 78.2% retention after 1000 charge–discharge cycles even at a high current density of 10 A g−1. These findings can be explained by the unique integral characteristics of 3D NiCo2O4 hollow spheres with high electron conductivity, large surface area and numerous open spaces between neighboring mesoporous ultrathin nanosheets, which can offer many facile diffusion paths for ion/electrolyte and greatly improve the electron/ion transfer within the electrode and at the electrode–electrolyte interfaces.

A newly designed 3D oxide nanosheet array catalyst, CoMgAlO-array, with small-sized active Co3O4 species (5.7 nm) highly dispersed on a Mg/Al-oxide matrix was obtained by calcining the hierarchical structured array-like CoMgAl-layered double hydroxide (LDH)/graphene hybrid prepared by a modified coprecipitation method. The superior redox property of CoMgAlO-array contributes to its much higher NOx storage capacity (NSC) and catalytic soot combustion activity than CoMgAlO. For NOx storage, the highly dispersed Co3O4 phases of CoMgAlO-array efficiently facilitate the adsorption of gaseous NO and then oxidation to chelating bidentate nitrate and bridging bidentate nitrate as the major adsorbed species at 300 °C with NSC of 8.8 mg g−1, while at 100 °C (NSC: 10.4 mg g−1), despite the larger amounts of nitrites and nitrates formed, CoMgAlO-array with higher oxidation ability can rapidly convert initially formed bridging bidentate nitrite to the much more stable monodentate nitrate. More remarkably, the formed nitrates over CoMgAlO-array can be rapidly reduced within 1 min in 0.7% H2/N2 at 300 °C and the catalyst exhibits excellently recyclable NOx storage/reduction abilities. For soot combustion, on one hand, CoMgAlO-array possesses stronger NO oxidation ability due to the small-sized Co3O4 phase; on the other hand, the unique hierarchical structure of the catalyst with larger external surface area can provide much more contact sites with gaseous NO and solid soot, thus greatly improving the catalytic activity with lower characteristic temperature (Tm) for maximal soot conversion and activation energy than CoMgAlO in both tight contact and loose contact modes. The NOx storage/soot combustion mechanism and the function of Co in 3D oxide nanosheet array catalyst are proposed and discussed on the basis of these observations.

Novel zirconium-doped porous magadiite heterostructures (PMH-xZr, x = Zr/Si molar ratio) are fabricated by two-dimensional intragallery cosurfactant-directing in situ hydrolysis–condensation–polymerization method of TEOS and Zr-n-propoxide from synthetic Na-magadiite and characterized systematically by XRD, SEM/(HR)TEM, 29Si MAS NMR, BET, UV-vis DRS, NH3-TPD, pyridine FT-IR, and XPS techniques. The results indicate that the obtained PMH-xZr materials possess high surface area and high thermal stability upon effective assembly of interlayer Zr-doped meso-structural silica and the layers of magadiite. The PMH-xZr samples with x < 0.2 show successful incorporation of Zr into the lattice of interlayer mesostructural silica framework leading to considerably generated Brønsted sites Zr–O(H)–Si and obviously increased Lewis sites Zr–O–Si along with well-kept layered supermicro-mesostructure, while PMH-0.2Zr shows delaminated layers. PMH-0.1Zr exhibits the highest liquid-phase benzoylation activity of anisole with benzoyl chloride (Conv. 99.5%) and yield for 4-methoxybenzophenone (4-MBP) (94.1%) due to the strongest synergy between the high concentration of surface Brønsted sites and supermicro-mesostructure. PMH-0.1Zr can be reused by no further chemical treatment for at least five runs with a slightly reduced 4-MBP yield. These PMH-xZr materials can serve as a promising solid acid catalyst and/or acidic support with high surface area and thermal stability in broad range of catalysis applications.

M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 ± 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ∼0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46500 h−1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au–support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.

Novel hierarchical core@shell structured salicylate (SA) intercalated ZnAl-LDH (layered double hydroxides) magnetic nanovehicles were obtained via a special double-drop coprecipitation strategy assembling organo-ZnAl-LDH nanocrystals onto the surface of Fe3O4 submicrospheres (∼480 nm) from cheap aspirin and Zn- and Al-nitrates in alkaline solutions. The obtained Fe3O4@SA-LDH-r nanovehicles exhibit varied morphologies with hexagonal LDH ab-face horizontal, vertical, and vertical/slant/horizontal to the surfaces of Fe3O4 upon proper mass ratio (r) of Zn-salt to Fe3O4 from 1.93 to 7.71 in a low supersaturation system and possess moderate drug loadings and strong superparamagnetism. An in vitro release study reveals that under “no MF” mode (without external magnetic field) the SA release exhibits the higher accumulated release amount and smaller half-life (t0.5) for Fe3O4@SA-LDH-3.85 (41.2%, 1.63 min) and Fe3O4@SA-LDH-7.71 (51.1%, 1.66 min) probably owing to their mainly vertical LDH orientations, while the dramatically reduced SA release (10.0%) and greatly elongated t0.5 (25.6 min) for Fe3O4@SA-LDH-1.93 may be due to its relatively stronger host–guest interaction and compact horizontally oriented LDH shell stack. Under “MF on” mode, all the magnetic samples show a detectable reduced SA release owing to the particle–particle interactions among the magnetic nanovehicles. The kinetic fittings show that the release processes of all the samples involve the bulk and surface diffusion. The SA release from Fe3O4@SA-LDH-1.93 is mainly determined by the interparticle diffusion among the horizontally oriented LDH shell nanocrystals while those of Fe3O4@SA-LDH-3.85 and Fe3O4@SA-LDH-7.71 mainly involve the interlayer intraparticle diffusion between LDHs layers due to their largely vertical LDH shell nanocrystals.Keywords: hierarchical core@shell structure; in vitro drug release; organo-layered double hydroxides; salicylate; superparamagnetism; vertically oriented growth

Novel hierarchical core@shell structured magnetic nanocatalysts of various morphologies involving ternary Cu-based layered double hydroxide CuMgAl-LDH shells and Fe3O4 cores were prepared via one-pot coprecipitation assembly and systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning/transmission electron microscopy (SEM/TEM)/high-resolution (HR) TEM, vibrating-sample magnetometry (VSM), H2-temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The nanocatalyst Fe3O4@CuMgAl-1 is revealed as a ca. 50 nm thick CuMgAl-LDH nanoshell consisting of 20 nm plate-like LDH particles horizontally coated onto the surface of the Fe3O4 core (ca. 500 nm in diameter), while Fe3O4@CuMgAl-2 shows honeycomb-like morphology with ca. 200 nm hexagonal plate-like LDH particles vertically grown on the surface of the Fe3O4 core. Both magnetic nanocatalysts exhibit higher catalytic activity for phenol hydroxylation by H2O2 than pure CuMgAl-LDH, and the former is better than the latter. These results can be rationally explained by a hydroxyl radical mechanism, resulting from Cu2+/Fe2+ and H2O2via a Fenton-like reagent, enhanced by the synergetic effect between the CuMgAl-LDH shell and the Fe3O4 core, possibly via a Cu–O–Fe linkage. In addition, the as-prepared magnetic nanocatalysts possess strong magnetic properties and a high magnetic reuse efficiency.

Novel Fe-incorporated anatase TiO2 nanosheet hierarchical spheres with predominant {001} facets were first prepared via a facile one-pot solvothermal route. The obtained {001}-0.1%Fe-AHSs exhibit excellent visible light photodegradation activity for methylene blue attributed to 94% {001} facets and uniformly incorporated Fe3+ ions in the TiO2 lattice.

Novel magnetic core-shell hierarchical composite submicrospheres Fe3O4@CuNiAl-LDH were facilely synthesized by coprecipitation of CuNiAl-layered double hydroxide (LDH) over the surface of pre-prepared magnetite submicrospheres in both methanol–water and water media under ambient conditions and systematically characterized by SEM/TEM, XRD, ICP, TGA, BET and VSM techniques. The as-fabricated composites possess center-hollowed core-shell hierarchical structure and strong magnetic susceptivity. Particularly, the composite submicrospheres obtained in water present honeycomb-like morphology with thin CuNiAl-LDH nanoplatelets (ca. 100 nm × 21 nm) staggered perpendicularly oriented grown on the surface of Fe3O4 core, affording to a cellular structure resulting in high specific surface area of the Fe3O4@CuNiAl-LDH composite. The formation mechanism of the Fe3O4@CuNiAl-LDH submicrospheres is tentatively proposed.A hierarchical nanocomposite Fe3O4@CuNiAl-LDH was rapidly fabricated over center-hollowed Fe3O4 spheres in water at room temperature and the interconnected CuNiAl-LDH thin platelet-like particles vertically oriented to Fe3O4 wall give a honeycomb-like submicrosphere with large surface area and pore volume implying its potential application as catalyst and drug targeting delivery vector along with its strong magnetization.Highlights► Facile synthesis of hierarchical core-shell magnetic nanocomposites Fe3O4@CuNiAl-LDH. ► Staggered CuNiAl-LDH nanoplatelets vertically oriented to center-hollowed Fe3O4 wall. ► Honeycomb-like composite submicrosphere has high surface area and strong magnetism. ► A possible formation mechanism for honeycomb-like Fe3O4@CuNiAl-LDH submicrospheres.

A novel core–shell structural Fe3O4@MgAl–LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl–LDH surface of Fe3O4@MgAl–LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.

Nearly monodispersed magnetic Fe3O4@DFUR–LDH submicro particles containing the anticancer agent DFUR were prepared via a coprecipitation-calcination-reconstruction strategy of LDH materials over the surface of Fe3O4 particles, and present well-defined core–shell structure, strong magnetization and obvious magnetically controlled drug delivery and release properties.

We present a facile surfactant-free solvothermal method for the fabrication of nearly monodispersed Fe3O4 submicroparticles with tunable particle sizes ranging from 130 to 420 nm by varying the concentration of single iron source FeCl3·6H2O in initial solutions. The morphology and crystal structure of the as-prepared Fe3O4 submicroparticles have been well characterized by using SEM/TEM/HRTEM, XRD, FT-IR, Raman spectroscopy, and XPS methods. It is found that the Fe3O4 particles present single-crystal nature and strong ferromagnetic property with magnetization saturation values ranged in 54.3–88.7 emu·g–1. A complexation–aggregation–phase transformation formation mechanism was first proposed for the nearly monodispersed single-crystal Fe3O4 submicroparticles based upon the quasi-in situ monitoring of the morphology and structure evolution of the samples during the synthesis process. These size-tunable nearly monodispersed Fe3O4 submicroparticles are expected to have promising applications in wide research fields such as bioseparation, targeted drug delivery, and catalysis.

Dodecylbenzenesulfonate (DBS) modified NiRTi layered double hydroxides (LDHs) with different Ni/Ti molar ratios were prepared as hydrophobic organics sorbent by one-step co-precipitation method. The basal spacing of DBS−NiRTi (d003 = 2.99−3.54 nm) is significantly increased compared with cyanate-intecalated Ni5Ti−LDH (0.73 nm) due to the intercalation of surfactant anions between the LDH layers. The greatly enhanced contact angle (123.5−144.2°) for water and the reduced surface area (1.72−3.25 m2/g) of DBS−NiRTi nanocomposites demonstrate their strong hydrophobic property. The highest sorption capacity for pentachlorophenol (PCP) of DBS−Ni5Ti among all samples is intimately related to its stacking model of the interlayer hydrophobic moiety and organic carbon content. The linear model well-fits for PCP sorption isotherms on DBS−NiRTi (R2 > 0.96), implying a partitioning sorption process. Along with the effect of medium pH and temperature on PCP sorption−desorption study on DBS−Ni5Ti, an adsolubilization mechanism, an exothermic sorption nature, and a significant hysteresis phenomenon during sorption−desorption process are revealed.

A novel magnetic nanohybrid involving non-steroid anti-inflammatory drug diclofenac (DIC) intercalated Mg–Al layered double hydroxides (LDH) coated on magnesium ferrite particles was assembled via a one step coprecipitation self-assembly method. The XRD, FT-IR and ICP measurements reveal that the magnetic nanohybrid consists of both DIC-LDH nanocrystallite and magnesium ferrite phases. The TEM image shows that the magnetic nanohybrid presents well-defined core-shell structure with diameter in the range of 90–150 nm. Compared to pure DIC-LDH, an obviously smaller dimension and less sharp hexagonal morphology of the coated DIC-LDH nanocrystallites in magnetic hybrids is observed due to a heterogeneous nucleation and crystal growth process with the introduction of the magnetic core. The in vitro drug release rate of the magnetic nanohybrid was thus enhanced owing to the much smaller size of the coated DIC-LDH nanoparticles on the surface of the magnetic core. However, under an external magnetic field of 0.15 Tesla, the drug release rate of the magnetic nanohybrid decreases dramatically owing to the aggregation of the magnetic nanohybrid particles triggered by non-contact magnetic force. The kinetic data reveal that the release of DIC from the magnetic nanohybrid is controlled by particle diffusion, and the release rate is mainly affected by the particle size and the aggregation extent of the hybrid magnetic particles. Additionally, the obtained nanohybrid has a strong magnetization response, implying the possibility of application in magnetic drug targeting.

LDH (layered double hydroxides)-based magnetic-sensitive drug−inorganic nanohybrids were assembled by a one-step co-precipitation method. The effect of a magnetic substance on the microstructure and drug release behavior of ibuprofen (IBU)-intercalated Mg−Al−LDH in magnetic nanohybrids was systematically studied via XRD, TEM, XPS, and VSM methods and in vitro release with and without an external magnetic field (MF). The results reveal a well-defined core−shell structure with a gray IBU−LDH shell coated onto the surface of a dark magnetic core and superior magnetic sensitivity of the magnetic nanohybrids. Compared with the clear platelets of the pure IBU−LDH, the IBU−LDH coatings in magnetic nanohybrids exhibit more like a compact stacking film fully covering the magnetic core and their particle sizes and thickness decrease with increasing core contents, explaining an enhanced release rate under no MF. While under a 1500 G MF, the release rate is greatly reduced with increasing core content due to the instant aggregation of the magnetic nanohybrid particles induced by the external MF. The release mechanism was discussed, and a primarily pulsatile drug release upon a consecutive MF “on−off” operation was also achieved.

Inorganic sulfate- and organic dodecylbenzenesulfonate (DBS)-intercalated zinc–iron layered double hydroxides (LDHs) materials were prepared by one-step coprecipitation method from a mixed salt solutions containing Zn(II), Fe(II) and Fe(III) salts. The as-prepared samples have been characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption, scanning electron microscopy (SEM), inductively coupled plasma emission spectroscopy (ICP), and Mössbauer spectroscopy (MS). The XRD analyses demonstrate the typical LDH-like layered structural characteristics of both products. The room temperature MS results reveal the characteristics of both the Fe(II) and Fe(III) species for SO42−-containing product, while only the Fe(III) characteristic for DBS-containing one. The combination characterization results and Rietveld analysis illustrate that the SO42−-containing product possesses the Green Rust two (GR2)-like crystal structure with an approximate chemical composition of [Zn0.435·FeII0.094·FeIII0.470·(OH)2]·(SO42−)0.235·1.0H2O, while the DBS-containing one exhibits the common LDH compound-like structure. The contact angle measurement indicates the evident hydrophobic properties of DBS-containing nanocomposite, compared with SO42−-containing product, due to the modification of the internal and external surface of LDHs by the organic hydrophobic chain of DBS.For Zn2+–Fe2+–Fe3+ GR2(SO42−), according to the derived chemical formula, Fe3+ was arranged at 1a (0, 0, 0) position, while all Zn2+ were in 2d position with the occupancy 0.645, and the left part of 2d positions were taken by Fe2+/Fe3+.

A core–shell structured magnetic layered organic–inorganic material involving 5-aminosalicylic acid (5-ASA) intercalated Zn–Al layered double hydroxides (LDHs) and magnesium ferrite (MgFe2O4) is assembled by a coprecipitation method. The powder X-ray diffraction results show the coexistence of the clear but weak diffractions of MgFe2O4 and ordered relatively stronger reflections of 5-ASA intercalated LDHs. The TEM image of magnetic 5-ASA intercalated LDHs reveals that the LDHs layer covers the MgFe2O4 particles or their aggregates with particle size of 50–80 nm. The vibration sample magnetization (VSM) measurements exhibit the increase in saturation magnetization of magnetic 5-ASA intercalated LDHs samples with increasing amount of magnetic core. The XPS analyses account for a majority of Zn, Al and O atoms on the surface of magnetic particles. It is suggested that the magnetic core MgFe2O4 was coated with LDHs layer probably through Zn–O–Mg and Al–O–Mg linkages, and a core–shell structured model is tentatively proposed.A schematic structural model of nanosized magnetic organic–inorganic hybrid composite involving 5-aminosalicylic acid intercalated layered double hydroxides coated on a ferrite core.

For fully controlled drug release, it is important to completely understand the microstructure and nature of the layered double hydroxide that ultimately control drug release properties. In this study, a series of novel doxifluridine intercalated Mg–Al-layered double hydroxide (DFUR–LDH) microhybrids were fabricated via the reconstruction method. With increasing aging pH values from 7.2 to 9.5, two different LDH phases with varied basal spacings (d003) are formed. The DFUR–LDHr1.7p7.2 with d003 1.91 nm presents continuous worm-like morphology and possible bilayer interlayer arrangement, while DFUR–LDHr2.0p9.5 with d003 0.82 nm possesses discontinuous plate-like morphology and multi-sites interacted interlayer arrangement. Consequently, the in vitro release shows that the former has much longer release duration and a little faster initial release due to the weaker interaction between DFUR and LDH layers than that of the latter. The in vitro release data can be well described by the Bhaskar equation and modified Freundlich model, revealing that the release mechanism of DFUR from DFUR–LDH microhybrids is heterogeneous particle diffusion. Furthermore, the enteric polymer modified DFUR–LDHr1.7p7.2/L100 microspheres present no obvious release in pH 1.2 HCl solution, but continuous release of 79% in pH 6.8 and 7.4 PBS, suggesting a readily controlled release behavior upon the varied medium pH and potential application in colon specific drug delivery in cancer therapy.

A series of nickel-based layered double hydroxides supported nearly atomic precise Au25 nanoclusters catalysts, and especially Au25/NixAl-LDH systems (x = Ni/Al, 2, 3, 4) were fabricated via modified electrostatic adsorption of captopril-capped clusters Au25Capt18 onto the predispersed positively-charged NixAl-LDH supports followed by proper calcination. Detailed characterizations show that the ultrafine gold clusters of ∼0.9 nm were well dispersed on the edge sites of hexagonal plate-like particles of NixAl-LDH (x = 2, 3) originated from their ordered LDH layers with more Ni–OH sites and strong Au–LDH synergy, while slightly aggregated to ∼1.1 nm on the irregular Ni4Al-LDH due to its poor layer structure along with doped nickel oxide. The catalysts exhibit excellent activity for selective oxidation of 1-phenylethanol to acetophenone with molecular oxygen under base-free, and the activity follows an increased order of Au25/Ni4Al-LDH < Au25/Ni2Al-LDH < Au25/Ni3Al-LDH. The Au25/Ni3Al-LDH shows the highest activity with TOF of 6780 h−1 in toluene and 118500 h−1 in solvent-free and can be applied for a wide range of alcohols, mainly ascribed to ultrafine gold clusters and strongest gold–LDH interaction associated with the highly ordered Ni3Al-LDH layers. Similar regularity is found in the Au25/NixMn-LDH and Au25/Ni3−xMnxFe-LDH systems. The Au25/Ni3Al-LDH can be reused 5 times without loss of activity. The least-squares fit analysis yields the rate constant (k) and apparent activation energy (Ea) of Au25/NixAl-LDH catalysts for 1-phenylethanol oxidation, and the order of k and Ea values act in accordance with their reactivities.

A newly designed 3D oxide nanosheet array catalyst, CoMgAlO-array, with small-sized active Co3O4 species (5.7 nm) highly dispersed on a Mg/Al-oxide matrix was obtained by calcining the hierarchical structured array-like CoMgAl-layered double hydroxide (LDH)/graphene hybrid prepared by a modified coprecipitation method. The superior redox property of CoMgAlO-array contributes to its much higher NOx storage capacity (NSC) and catalytic soot combustion activity than CoMgAlO. For NOx storage, the highly dispersed Co3O4 phases of CoMgAlO-array efficiently facilitate the adsorption of gaseous NO and then oxidation to chelating bidentate nitrate and bridging bidentate nitrate as the major adsorbed species at 300 °C with NSC of 8.8 mg g−1, while at 100 °C (NSC: 10.4 mg g−1), despite the larger amounts of nitrites and nitrates formed, CoMgAlO-array with higher oxidation ability can rapidly convert initially formed bridging bidentate nitrite to the much more stable monodentate nitrate. More remarkably, the formed nitrates over CoMgAlO-array can be rapidly reduced within 1 min in 0.7% H2/N2 at 300 °C and the catalyst exhibits excellently recyclable NOx storage/reduction abilities. For soot combustion, on one hand, CoMgAlO-array possesses stronger NO oxidation ability due to the small-sized Co3O4 phase; on the other hand, the unique hierarchical structure of the catalyst with larger external surface area can provide much more contact sites with gaseous NO and solid soot, thus greatly improving the catalytic activity with lower characteristic temperature (Tm) for maximal soot conversion and activation energy than CoMgAlO in both tight contact and loose contact modes. The NOx storage/soot combustion mechanism and the function of Co in 3D oxide nanosheet array catalyst are proposed and discussed on the basis of these observations.

Nearly monodispersed magnetic Fe3O4@DFUR–LDH submicro particles containing the anticancer agent DFUR were prepared via a coprecipitation-calcination-reconstruction strategy of LDH materials over the surface of Fe3O4 particles, and present well-defined core–shell structure, strong magnetization and obvious magnetically controlled drug delivery and release properties.

A novel core–shell structural Fe3O4@MgAl–LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl–LDH surface of Fe3O4@MgAl–LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.

Novel hierarchical core@shell structured magnetic nanocatalysts of various morphologies involving ternary Cu-based layered double hydroxide CuMgAl-LDH shells and Fe3O4 cores were prepared via one-pot coprecipitation assembly and systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning/transmission electron microscopy (SEM/TEM)/high-resolution (HR) TEM, vibrating-sample magnetometry (VSM), H2-temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The nanocatalyst Fe3O4@CuMgAl-1 is revealed as a ca. 50 nm thick CuMgAl-LDH nanoshell consisting of 20 nm plate-like LDH particles horizontally coated onto the surface of the Fe3O4 core (ca. 500 nm in diameter), while Fe3O4@CuMgAl-2 shows honeycomb-like morphology with ca. 200 nm hexagonal plate-like LDH particles vertically grown on the surface of the Fe3O4 core. Both magnetic nanocatalysts exhibit higher catalytic activity for phenol hydroxylation by H2O2 than pure CuMgAl-LDH, and the former is better than the latter. These results can be rationally explained by a hydroxyl radical mechanism, resulting from Cu2+/Fe2+ and H2O2via a Fenton-like reagent, enhanced by the synergetic effect between the CuMgAl-LDH shell and the Fe3O4 core, possibly via a Cu–O–Fe linkage. In addition, the as-prepared magnetic nanocatalysts possess strong magnetic properties and a high magnetic reuse efficiency.

A series of novel hierarchical nanosheet array-like hybrids xCu-LDH/rGO (xCu-LDH: CuxMg3−xAl-layered double hydroxide (x = 0.5, 1.0, and 1.5), rGO: reduced graphene oxide) were assembled via a facile and green aqueous-phase coprecipitation method. Systematic characterization suggests that the hybrids were constructed by hexagonal LDH nanoplates (∼70 nm × 4.5 nm) interdigitated vertical to the surface of single-layer rGO. All the xCu-LDH/rGO hybrids exhibit a remarkable higher activity for catalytic reduction of 4-nitrophenol (4-NP) compared with pure Cu-LDH, commercial Pt/C and other recently reported Cu-related catalysts. These findings were carefully explained by deep study of the catalyst treated with NaBH4, and the xCu-LDH/rGO hybrids as a potential Cu2O reservoir were revealed for the first time. Typically for 1.0Cu-LDH/rGO, a part of Cu2+ ions on LDH layers were instantaneously in situ reduced to well-dispersed ultrafine Cu2O nanoparticles (∼6.8 nm) by NaBH4 in an aqueous reduction system and thus formed relatively strong interaction between Cu2O and LDH/rGO greatly favoring enhanced activity for the reduction of 4-NP, other nitroarenes and organic dyes at room temperature. The excellent activity of the xCu-LDH/rGO hybrids can be attributed to the possible Cu2O–Cu-LDH–rGO three-phase synergistic effect, increased adsorption capacity for reactants via π–π stacking, and unique nanoarray-like morphology of the hybrids. Moreover, the 1.0Cu-LDH/rGO can be cycled for 20 runs without significant loss of activity, giving the hybrid long-term stability.

A novel magnetic nanohybrid involving non-steroid anti-inflammatory drug diclofenac (DIC) intercalated Mg–Al layered double hydroxides (LDH) coated on magnesium ferrite particles was assembled via a one step coprecipitation self-assembly method. The XRD, FT-IR and ICP measurements reveal that the magnetic nanohybrid consists of both DIC-LDH nanocrystallite and magnesium ferrite phases. The TEM image shows that the magnetic nanohybrid presents well-defined core-shell structure with diameter in the range of 90–150 nm. Compared to pure DIC-LDH, an obviously smaller dimension and less sharp hexagonal morphology of the coated DIC-LDH nanocrystallites in magnetic hybrids is observed due to a heterogeneous nucleation and crystal growth process with the introduction of the magnetic core. The in vitro drug release rate of the magnetic nanohybrid was thus enhanced owing to the much smaller size of the coated DIC-LDH nanoparticles on the surface of the magnetic core. However, under an external magnetic field of 0.15 Tesla, the drug release rate of the magnetic nanohybrid decreases dramatically owing to the aggregation of the magnetic nanohybrid particles triggered by non-contact magnetic force. The kinetic data reveal that the release of DIC from the magnetic nanohybrid is controlled by particle diffusion, and the release rate is mainly affected by the particle size and the aggregation extent of the hybrid magnetic particles. Additionally, the obtained nanohybrid has a strong magnetization response, implying the possibility of application in magnetic drug targeting.