Interaction of Au with thin ZrO2 films: influence of ZrO2 morphology on the adsorption and thermal stability of Au nanoparticles

Synthesis and characterization of ZrO2-ZnO heterojunction composite for isopropanol detection

We prepared ZrO2-ZnO heterojunction composites by a simple hydrothermal method as materials sensitive to isopropanol gas. The 5% ZrO2-ZnO sample presented a uniform rod-like structure. The optimum operating temperature, sensitivity and response/recovery times were measured to investigate the response of ZrO2-ZnO composites to isopropanol. The sensor based on 5% ZrO2-ZnO composites at an optimum temperature of 260 °C had a response to 100 ppm isopropanol of up to 172.46, which was about 3.6 times higher than that of pure ZnO. The sensor also exhibited fast response and recovery times of 5 s and 11 s, respectively. The gas-sensitive properties can be attributed to the rod-like structure, heterojunction structure and catalytic activity of ZrO2. These results would contribute in expanding the application of ZrO2 in gas sensors.

In situ Dispersed Nano-Au on Zr-Suboxides as Active Cathode for Direct CO2 Electroreduction in Solid Oxide Electrolysis Cells

CO₂ electrochemical reduction in solid oxide electrolysis cells is an effective way to combine CO₂ conversion and renewable electricity storage. A Au layer is often used as a current collector, whereas Au nanoparticles are rarely used as a cathode because it is difficult to keep nanosized Au at high temperatures. Here we dispersed a Au layer into Au nanoparticles (down to 2 nm) at 800 °C by applying high voltages. A 75-fold decrease in the polarization resistance was observed, accompanied by a 38-fold improvement in the cell current density. Combining electronic microscopy, in situ near-ambient pressure X-ray photoelectron spectroscopy, and theoretical calculations, we found that the interface between the Au layer and the electrolyte (yttria-stabilized zirconia (YSZ)) was reconstructed into nano-Au/Zr-suboxide interfaces, which are active sites that show a much lower reaction activation energy than that of the Au/YSZ interface. The formation of Zr-suboxides promotes Au dispersion and Au nanoparticle stabilization due to the strong interaction between Au and Zr-suboxides.

Enhanced fluoride removal by hierarchically porous carbon foam monolith with high loading of UiO-66

Environmental concern associated with excess fluoride has intrigued the unceasing exploration of new multifunctional hybrid materials to mitigate any undesirable consequence to human health. Herein, a novel hybrid monolith has been successfully fabricated via a facile in-situ growth strategy for highly efficient defluoridation from contaminated waters, in which homogeneously dispersed UiO-66 particles are perfectly anchored on three dimensional (3D) porous carbon foam (CF). Benefiting from fully exposed active sites, excellent pore accessibility and efficient mass transport, the integrated UiO-66/CF hybrid monolith exhibits fast adsorption kinetics, and outstanding uptake capacity toward fluoride as high as 295 mg g^-1, which greatly outperforms the previously reported adsorbents. Furthermore, the fluoride removal efficiency of the spent monolith can reach up to 70% after four cycles, accompanied by facile separation nature and outstanding water stability. More significantly, the resulting UiO-66/CF packed column (0.36 g) can continuously treat 400 mL of F^- solution with 6.2 mg L^-1 before the breakthrough point occurs, highlight its potential feasibility for fluoride removal in the practical applicability.

Trade-off between Zr Passivation and Sn Doping on Hematite Nanorod Photoanodes for Efficient Solar Water Oxidation: Effects of a ZrO2 Underlayer and FTO Deformation

Herein we report the influence of a ZrO2 underlayer on the PEC (photoelectrochemical) behavior of hematite nanorod photoanodes for efficient solar water splitting. Particular attention was given to the cathodic shift in onset potential and photocurrent enhancement. Akaganite (β-FeOOH) nanorods were grown on ZrO2-coated FTO (fluorine-doped tin oxide) substrates. Sintering at 800 °C transformed akaganite to the hematite (α-Fe2O3) phase and induced Sn diffusion into the crystal structure of hematite nanorods from the FTO substrates and surface migration, shallow doping of Zr atoms from the ZrO2 underlayer. The ZrO2 underlayer-treated photoanode showed better water oxidation performance compared to the pristine (α-Fe2O3) photoanode. A cathodic shift in the onset potential and photocurrent enhancement was achieved by surface passivation and shallow doping of Zr from the ZrO2 underlayer, along with Sn doping from the FTO substrate to the crystal lattice of hematite nanorods. The Zr based hematite nanorod photoanode achieved 1 mA/cm(2) at 1.23 VRHE with a low turn-on voltage of 0.80 VRHE. Sn doping and Zr passivation, as well as shallow doping, were confirmed by XPS, Iph, and M-S plot analyses. Electrochemical impedance spectroscopy revealed that the presence of a ZrO2 underlayer decreased the deformation of FTO substrate, improved electron transfer at the hematite/FTO interface and increased charge-transfer resistance at the electrolyte/hematite interface. This is the first systematic investigation of the effects of Zr passivation, shallow doping, and Sn doping on hematite nanorod photoanodes through application of a ZrO2 underlayer on the FTO substrate.

Aun (n = 1–16) clusters on the ZrO2(111) surface: a DFT+U investigation

Au_n (n = 1–16) clusters supported on the monoclinic ZrO₂ surface prefer quasi-planar geometries that lay flat on the surface.

Preparing magnetic multicomponent catalysts via a bio-inspired assembly for heterogeneous reactions

A facile synthetic approach for preparing magnetic porous catalysts, from various inorganic compounds loaded by a pyrogallic acid (PG) assisted layer-by-layer (LbL) coating.

Gold nanoparticles supported in zirconia-ceria mesoporous thin films: a highly active reusable heterogeneous nanocatalyst

Gold nanoparticles (NP) trapped in the mesopores of mixed zirconia-ceria thin films are prepared in a straightforward and reproducible way. The films exhibit enhanced stability and excellent catalytic activity in nitro-group reduction by borohydride and electrocatalytic activity in CO and ethanol oxidation and oxygen reduction.

Novel β-ketoiminato complexes of zirconium: synthesis, characterization and evaluation for solution based processing of ZrO2 thin films

Treatment of tetrakis(diethylamido)zirconium(IV); [Zr(NEt2)4] with a series of β-ketoimines ({[RHN]C(CH3)=C(H)C(CH3)=O} where R is a functionalized side-chain; 4-(2-methoxyethylamino)pent-3-en-2-one, Hmeap; 4-(3-methoxypropylamino)pent-3-en-2-one, Hmpap; 4-(2-(dimethylamino)ethylamino)pent-3-en-2-one, Hdeap; 4-(3-(dimethylamino)propylamino)pent-3-en-2-one, Hdpap) leads to an amine substitution reaction that yielded novel monomeric heteroleptic mixed amido-ketoiminato complexes of the type bis(4-(2-methoxyethylamino)pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (1), bis(4-(3-methoxypropylamino)pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (2), and bis(4-(3-(dimethylamino)propylamino)pent-3-en-2-onato)bis(diethylamido)zirconium(IV) (3), and eight-coordinated homoleptic complexes tetrakis(4-(2-methoxyethylamino)pent-3-en-2-onato)zirconium(IV) (4) and tetrakis(4-(2-(dimethylamino)ethylamino)pent-3-en-2-onato)zirconium(IV) (5), depending on the ratio of the ligand to zirconium. Adopting a similar strategy with zirconium alkoxide, namely [Zr(O(i)Pr)4·(i)PrOH], with β-ketoimine Hmeap, leads to the formation of a dimer, bis(μ2-isopropoxo)bis(4-(2-methoxyethylamino)pent-3-en-2-onato)tetrakis(isopropoxo)dizirconium(IV) (6). The newly synthesised complexes were characterized by NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, elemental analysis and thermal analysis. The low decomposition temperature facilitated by the stepwise elimination of the ketominate ligand from the complex and the stability of the complexes obtained in air as well as in solution makes them highly suitable for solution based processing of ZrO2 thin films, which is demonstrated using compound 5 on Si(100) substrates. High quality ZrO2 films were obtained and were investigated for their structure, morphology, composition and optical properties. Low temperature crystallisation of ZrO2 is achieved by a simple chemical deposition process using the new class of Zr precursors and the films exhibit an optical transmittance above 90%.