Effects of La, Ce, and Y Oxides on SnO2Catalysts for CO and CH4Oxidation

Incompatibility of Pure SnO2 Thin Films for Room-Temperature Gas Sensing Application

Despite the high sensitivity and selectivity, the high operating temperature required for activation energy of tin oxide (SnO2) still stands as a drawback for SnO2 based gas sensors. In this work, the SnO2 thin films were deposited through spray pyrolysis and were subjected to gas sensing at 27 °C (room temperature) towards different gases. The films exhibited a consistently low response of approximately 1 when tested to various VOCs. The type, concentration, and mobility of charge carriers were determined from the Hall measurements. The high carrier concentration accompanied by poor mobility and grain boundary scattering is supposed to hinder its performance at room temperature. The obtained film had spherical morphology, which lead to grain boundary scatterings and decreased the mobility of carriers.

Synergistic effect between Ce-doped SnO2 and bio-carbon for electrocatalytic degradation of tetracycline: Experiment, CFD, and DFT

Carbon-based sandwich-like electrocatalyst with a hierarchical structure, carbon sheet (CS)-loaded Ce-doped SnO₂ nanoparticles, were successfully prepared using a simple method, which presented a high-efficiency electrocatalytic performance for tetracycline decomposition. Among them, Sn_0.75Ce_0.25O_y/CS exhibits superior catalytic activity, such as more than 95% of tetracycline was removed (120 min), and over 90% of total organic carbon was mineralized (480 min). It is found from morphology observation and computational fluid dynamics simulation that the layered structure is conducive to improving the mass transfer efficiency. Through X-Ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectrum, and density functional theory calculation analyze that the structural defect in Sn_0.75Ce_0.25O_y caused by Ce doping is considered to play the key role. Moreover, electrochemical measurements and degradation experiments further prove that the outstanding catalytic performance is attributable to the initiated synergistic effect established between CS and Sn_0.75Ce_0.25O_y. These results explain the effectiveness of Sn_0.75Ce_0.25O_y/CS for the remediation of tetracycline-contaminated water and mitigating the potential risks and imply that the Sn_0.75Ce_0.25O_y/CS composite has a deeply practical value in tetracycline wastewater degradation and a promise for further application.

Optimizing the Microstructure of SnO2-CeO2 Binary Oxide Supported Palladium Catalysts for Efficient and Stable Methane Combustion

The preparation of palladium-based catalysts with both high catalytic activity and hydrothermal stability currently appears as a critical topic in methane combustion. Herein, we propose a facile strategy to boost the performance of SnO₂-CeO₂ binary oxide supported palladium catalysts by tuning the composition of supports. The coexistence of SnO₂ and CeO₂ phases in an appropriate ratio is favorable for the formation of both Pd_xCe_1-xO_2-δ and Pd_xSn_1-xO_2-δ solid solutions due to the reduced crystallite size. This unique microstructure could enhance the metal-support interaction to stabilize the active PdO phase and promote its reoxidation, meanwhile generating more oxygen vacancies to improve the reducibility of PdO. On account of the facilitated conversion of PdO ↔ Pd, coupled with the low-temperature dissociation of methane promoted by abundant active oxygen species, the Pd/5Sn5Ce catalyst exhibits a superior catalytic activity with a T₉₉ of ca. 360 °C, a robust stability under both dry and wet conditions, and an excellent thermal stability during heating-cooling light-off tests.

Band-Gap Engineering: A New Tool for Tailoring the Activity of Semiconducting Oxide Catalysts for CO Oxidation

Cation or anion vacancies in semiconducting oxides usually benefit activity for CO oxidation. To study the nature of vacancy engineering for a thermocatalytic reaction, we adopted lattice doping of cations with varied valence states to construct anion and cation vacancies in n-type and p-type semiconducting CeO₂ and NiO, respectively. Doping cations can effectively regulate the number of the vacancies, thus tailoring the activity for CO oxidation. The strong correlation of activation energy and specific activity with a catalyst band gap verified that the nature of vacancy engineering for activity of CeO₂ and NiO for CO oxidation can be attributed to tailoring of the band gap. The larger the vacancy amount, the smaller the band gap, and the lower the activation energy, thus giving a higher specific activity. Band-gap engineering, widely used for photocatalytic processes, can be a new tool for tailoring the activity of semiconducting oxide catalysts for thermocatalytic reactions.

FeCeOx Supported Ni, Sn Catalysts for the High-Temperature Water–Gas Shift Reaction

In this work, the effect of monometallic Ni or Sn and bimetallic NiSn deposition on the activity of FeCeOx catalysts in high-temperature water–gas (HT-WGS) reactions was investigated. It was found that the HT-WGS performance of FeCeOx has significantly improved after the deposition of Sn together with Ni on it. Furthermore, the bimetallic NiSn/FeCeOx catalyst showed higher activity compared to the monometallic Ni/FeCeOx and Sn/FeCeOx catalysts within the tested temperature range (450–600 °C). Although the Ni/FeCeOx catalyst showed methanation activity at a temperature below 550 °C, the NiSn/FeCeOx catalyst suppressed the methane formation to zero in the WGS. Besides, the NiSn/FeCeOx catalyst exhibited an excellent time-on-stream stability without methanation reaction, even at a steam-to-CO ratio as low as 0.8. The combination of Ni and Sn supported on FeCeOx led to a large lattice strain, the formation of NiSn alloy, and a strong synergistic effect between the bimetallic NiSn and FeCeOx mixed oxide support interface. All these features are very important in achieving the best activity and stability of NiSn/FeCeOx in the HT-WGS reaction.

Highly active and durable Pd nanocatalyst promoted by an oxygen-deficient terbium oxide (Tb4O7−x) support for hydrogenation and cross-coupling reactions

Oxygen-deficient Tb₄O_7−x as an effective promoter and support for Pd nanocatalysts holds great potential in hydrogenation and cross-coupling reactions.

Effect of Ce and La dopants in Co3O4 nanorods on the catalytic activity of CO and C3H6 oxidation

The catalytic activity is enhanced by Ce but inhibited by La dopant. The catalysts have been characterized in light of structural properties, reducibility, mobility of adsorbed oxygen and lattice oxygen, and surface reaction intermediates.

Enhancement mechanism of Sn on the catalytic performance of Cu/KIT-6 during the catalytic combustion of chlorobenzene

Sn promoted the redox capacity of Cu²⁺ and Sn⁴⁺, thus greatly reducing the surface chloride-deposition during the chlorobenzene catalytic combustion process.

Cerium and tin oxides anchored onto reduced graphene oxide for selective catalytic reduction of NO with NH3 at low temperatures

A series of cerium and tin oxides anchored on reduced graphene oxide (CeO2-SnO x /rGO) catalysts are synthesized using a hydrothermal method and their catalytic activities are investigated by selective catalytic reduction (SCR) of NO with NH3 in the temperature range of 120-280 °C. The results indicate that the CeO2-SnO x /rGO catalyst shows high SCR activity and high selectivity to N2 in the temperature range of 120-280 °C. The catalyst with a mass ratio of (Ce + Sn)/GO = 3.9 exhibits NO conversion of about 86% at 160 °C, above 97% NO conversion at temperatures of 200-280 °C and higher than 95% N2 selectivity at 120-280 °C. In addition, the catalyst presents a certain SO2 resistance. It is found that the highly dispersed CeO2 nanoparticles are deposited on the surface of rGO nanosheets, because of the incorporation of Sn4+ into the lattice of CeO2. The mesoporous structures of the CeO2-SnO x /rGO catalyst provides a large specific surface area and more active sites for facilitating the adsorption of reactant species, leading to high SCR activity. More importantly, the synergistic interaction between cerium and tin oxides is responsible for the excellent SCR activity, which results in a higher ratio of Ce3+/(Ce3+ + Ce4+), higher concentrations of surface chemisorbed oxygen and oxygen vacancies, more strong acid sites and stronger acid strength on the surface of the CeSn(3.9)/rGO catalyst.

SnO2 Nanostructures: Effect of Processing Parameters on Their Structural and Functional Properties

Zero- and 1D (one-dimensional) tin (IV) oxide nanostructures have been synthesized by thermal evaporation method, and a comparison of their morphology, crystal structure, sorption properties, specific surface area, as well as electrical characteristics has been performed. Synthesized SnO₂ nanomaterials were studied by X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), N₂ sorption/desorption technique, IR spectroscopy and, in addition, their current-voltage characteristics have also been measured. The single crystalline structures were obtained both in case of 0D (zero-dimensional) SnO₂ powders and in case of 0D nanofibers, as confirmed by electron diffraction of TEM. It was found that SnO₂ synthesis parameters significantly affect materials' properties by contributing to the difference in morphology, texture formation, changes in IR spectra of 1D structure as compared to 0D powders, increases in the specific surface area of nanofibers, and the alteration of current-voltage characteristics 0D and 1D SnO₂ nanostructures. It was established that gas sensors utilizing of 1D nanofibers significantly outperform those based on 0D powders by providing higher specific surface area and ohmic I-V characteristics.

Mesoporous Y2Sn2O7 pyrochlore with exposed (111) facets: an active and stable catalyst for CO oxidation

Mesoporous Y₂Sn₂O₇ pyrochlore with exposed (111) facets was successfully synthesized via a simple hydrothermal method and showed superior catalytic performance for CO oxidation.

Structural differences between Sb- and Nb-doped tin oxides and consequences for electrical conductivity

High surface area Nb and Sb-doped tin oxides are prepared by co-precipitation. The differences in conductivity are rationalised using HT-XRD, SSNMR and Nb K-edge XANES characterisation.

Elucidating the promotional effects of niobia on SnO2 for CO oxidation: developing an XRD extrapolation method to measure the lattice capacity of solid solutions

Using an XRD extrapolation method, the SnO₂ lattice capacity for Nb₂O₅ is quantified. A Sn–Nb solid solution without excess Nb₂O₅ is promising for CO oxidation.

Facile preparation of mesoporous Cu–Sn solid solutions as active catalysts for CO oxidation

A mesoporous Cu_0.5Sn_0.5O_y solid solution catalyst with Caramel-Treats-like morphology prepared easily by co-precipitation method exhibits remarkably improved CO oxidation activity and potent resistance to water vapour deactivation.

Sn-MFI as active, sulphur and water tolerant catalysts for selective reduction of NOx

Sn-MFI prepared hydrothermally was used for NOx-SCR. Sn was incorporated into the MFI framework to create a large quantity of Lewis acidic sites, active surface oxygen and mesopores, which improve the activity of the catalyst remarkably.

High surface area La2Sn2O7 pyrochlore as a novel, active and stable support for Pd for CO oxidation

A mesoporous La₂Sn₂O₇-HT pyrochlore with an unusually high surface area was successfully synthesized with a simple hydrothermal method at 200 °C. Due to its high surface area and the presence of more active oxygen species, Pd supported on this mesoporous La₂Sn₂O₇-HT shows remarkable CO oxidation activity.

Ce0.80M0.12Sn0.08O2−δ (M = Hf, Zr, Pr, and La) ternary oxide solid solutions with superior properties for CO oxidation

Ce_0.80Pr_0.12Sn_0.08O_2−δ combination catalyst exhibited highest CO oxidation activity owing to its high specific surface area, better reducibility, superior surface active oxygen species, and oxygen vacancies among various samples investigated.

Direct CO oxidation by lattice oxygen on the SnO2(110) surface: a DFT study

The process of CO oxidation by lattice oxygen on the SnO₂(110) surface and the recovery of the reduced surface by O₂ is presented.