Synthesis of Pd-Doped SnO2 and Flower-like Hierarchical Structures for Efficient and Rapid Detection of Ethanolamine

In this study, we successfully synthesized a Pd-doped SnO2 (Pd-SnO2) material with a flower-like hierarchical structure using the solvothermal method. The material's structural proper-ties were characterized employing techniques such as XRD, XPS, FESEM and HRTEM. A gas sensor fabricated from the 2.0 mol% Pd-SnO2 material demonstrated exceptional sensitivity (Ra/Rg = 106) to 100 ppm ethanolamine at an operating temperature of 150 °C, with rapid response/recovery times of 10 s and 12 s, respectively, along with excellent linearity, selectivity, and stability, and a detection limit down to 1 ppm. The superior gas-sensing performance is attributed to the distinctive flower-like hierarchical architecture of the Pd-SnO2 and the lattice distortions introduced by Pd doping, which substantially boost the material's sensing characteristics. Further analysis using density functional theory (DFT) has revealed that within the Pd-SnO2 system, Sn exhibits strong affinities for O and N, leading to high adsorption energies for ethanolamine, thus enhancing the system's selectivity and sensitivity to ethanolamine gas. This research introduces a novel approach for the efficient and rapid detection of ethanolamine gas.

High-Performance N-Butanol Gas Sensor Based on Iron-Doped Metal-Organic Framework-Derived Nickel Oxide and DFT Study

In this study, a straightforward two-step hydrothermal process was used to synthesize Fe-doped NiO nanomaterials. A number of characterization approaches were employed to explore the structure and morphology of the synthesized Fe-doped NiO. The as-prepared samples were multi-layered flower-like structures formed by nanoparticles, according to scanning electron microscopy and transmission electron microscopy studies. The findings of the study on gas sensing performance showed that the response of the 1.5 at % Fe-NiO sensor was nearly 100 times greater than that of the pure NiO sensor, and the lower limit of detection was greatly decreased (50 ppb). The 1.5 at % Fe-NiO sensor exhibited superior sensing performance for n-butanol. The incorporation of an appropriate amount of Fe into the NiO lattice modified the carrier concentration, which is the primary cause of the increased sensor performance of an appropriate amount of Fe-doped NiO. In addition, the density functional theory calculation method based on the first-principles theory was used to study the adsorption performance and electronic behavior of pure NiO and 1.5 at % Fe-NiO for n-butanol. The calculated results were consistent with the experimental results.

Enhanced NO2 gas-sensing performance by core-shell SnO2/ZIF-8 nanospheres

Timely detection of harmful, poisonous and air pollutant gases is of vital importance to the protection of human beings from exposure to rigorous gases. The development of gas-sensing devices based on sphere-like porous SnO₂/ZIF-8 nanocomposites is required to overcome this challenge. Nanostructures with high surface area, more porosity and hollow interior provide plenty of active cites for high responses in metal oxide gas sensors. The engineered gas sensors have excellent sensing sensitivity (164), rapid response and recovery times (60, 45 s), and favorable selectivity for NO₂ gases under 300 °C. Consequently, NO₂ gas sensors based on core-shell SnO₂/ZIF-8 nanospheres are regarded viable capacity industrial applicants.

Synthesis of Fe-doped NiO nanosheets on carbon cloth for improved catalytic performance in Li–O2 batteries

The substitution of Ni2+ in NiO with Fe3+ can significantly improve the cycling stability and discharge/recharge capacities of Li–O2 batteries.

Solvent Effect on the Solvothermal Synthesis of Mesoporous NiO Catalysts for Activation of Peroxymonosulfate to Degrade Organic Dyes

In this work, we successfully prepared three different mesoporous NiO nanostructures with preferential (111) planes using three different solvents-water, a water-ethanol mixture, and a water-ethylene glycol mixture. The NiO nanosheets prepared from the water-ethylene glycol mixture and denoted as NiO-EG showed a nanosheet morphology thinner than 10 nm, whereas the water-ethanol and water samples were 30-40 nm and above 100 nm thick, respectively. The NiO-EG catalyst was found to exhibit a high catalyzing ability to activate peroxymonosulfate (PMS) for decoloring dyes, by which 94.4% of acid orange 7 (AO7) was degraded under the following reaction conditions: AO7 = 50 mg/L, catalyst = 0.2 g/L, PMS = 0.8 g/L, pH = 7, and 30 min reaction time. The dye degradation rate was investigated as a function of the catalyst dosage, pH, and dye concentration. According to quenching experiments, it was found that SO4 •-, HO•, and O2 •- were the dominant radicals for AO7 degradation, and oxygen vacancies played a significant role in the generation of radicals. High surface area, thin flaky structure, rich oxygen vacancies, fast charge transport, and low diffusion impedance all enhanced the catalytic activity of NiO-EG, which exhibited the highest degradation ability due to its abundant accessible active sites for both adsorption and catalysis.

Oxygen-Defective Ultrathin BiVO4 Nanosheets for Enhanced Gas Sensing

BiVO₄ nanomaterials are potentially applicable in gas sensing, but the sensing performance is limited by the less active sites on the BiVO₄ surface. In this work, we propose a strategy to improve the gas-sensing performance of BiVO₄ by forming ultrathin nanosheets and introducing oxygen vacancies, which increase the surface active sites. Two-dimensional (2D) BiVO₄ nanosheets with oxygen vacancies are prepared through a colloidal method with the assistance of nitric acid. Gas sensors based on the oxygen-defective 2D ultrathin BiVO₄ nanosheets exhibit an enhanced sensing response, which is 3.4 times higher than those of the sensors based on oxygen-abundant BiVO₄ nanosheets. The density functional theory calculation is employed to uncover the promoting effects of oxygen vacancies on enhancing the O₂ adsorption capability of BiVO₄ nanosheets. This work is not only expected to build a wide range of 2D metal oxide semiconductors with a high gas-sensing performance but also gives an insight into the mechanism of the enhanced response induced by the oxygen vacancies, which will be a guideline for further designing high-performance sensing materials.

Synthesis of Single-Component Metal Oxides with Controllable Multi-Shelled Structure and their Morphology-Related Applications

Multi-shelled hollow spheres metal oxides, namely materials with more than three shells, have attracted increasing attention due to their unique structure. The preparation methods of typical metal oxides including NiO, Co₃ O₄ and ZnO etc. have been summarized in this review. Simultaneously, the parameters that influence the ultimate morphologies, shell number as well as the compositions have also been discussed. The potential application fields in energy conversion and storage, electromagnetic wave absorption, photocatalysis that related to the unique structure are also highlighted. Finally, the future researches of multi-shelled hollow spheres metal oxides are further discussed.

P–N heterointerface-determined acetone sensing characteristics of α-MoO3@NiO core@shell nanobelts

α-MoO₃@NiO nanocomposite with well-defined core@shell P–N heterojunction nanobelts was prepared which exhibited heterointerface-determined acetone sensing characteristics.

Extremely sensitive and accurate H2S sensor at room temperature fabricated with In-doped Co3O4 porous nanosheets

In-Doped Co₃O₄ porous nanosheets were synthesized and exhibited a fast response and high selectivity towards H₂S at room temperature.

Konjac glucomannan-templated synthesis of three-dimensional NiO nanostructures assembled from porous NiO nanoplates for gas sensors

Biopolymer template synthesis has attracted extensive interest for fabricating highly porous metal oxide nanostructures. In this report, a green template-based approach for the synthesis of three-dimensional (3D) NiO nanostructures assembled from porous NiO nanoplates is introduced using a konjac glucomannan (KGM) template. The Ni–KGM composites, which were formed by the immersion of KGM nanofibrils in nickel nitrate solution, were annealed in air at 600 °C to obtain the highly porous NiO nanoplates. The KGM nanofibrils were used as a sacrificial template, which was combusted at a high temperature for the formation of the porous nanostructures. The gas sensor properties of the porous NiO architecture were systematically investigated with four reduced gases including hydrogen sulfide, ammonia, carbon monoxide and hydrogen. The results indicate that the porous NiO nanoplates show a good detection of hydrogen sulfide with a rapid response and recovery speed at low concentrations.

Biopolymer template synthesis has attracted extensive interest for fabricating highly porous metal oxide nanostructures.