Concentration Of Chemisorbed Oxygen Research Articles

Effect of modified Ca-Al adsorbents on heavy metal fixation during co-combustion of coal and coconut shells: Experiments and simulations

As an alternative fuel, bio-waste coconut shells have shown promise in reducing pollution during the co-combustion process. In this study, a novel metal-mineral adsorbent, Ca-Al (Ca5Al6O14), was prepared and physically (ultrasonic) and chemically (ethylene glycol) modified to enhance its adsorption properties. Thermal adsorption experiments investigated the effect of the adsorbents on the fixation of six heavy metals (HMs): Cr, Cu, Mn, Ni, Pb, and Zn. XRD, SEM, BET, and XPS were used to analyze the adsorbents and the adsorption mechanism was investigated by combining lattice oxygen concentration and Factsage simulation calculations. The ecological risk assessment of heavy metals was used to comprehensively evaluate the fixation effects of the three Ca-Al adsorbents at different additive levels. The results showed that the modification significantly changed the morphological characteristics and oxygen activity of the Ca-Al adsorbents, increased the lattice oxygen and chemisorbed oxygen concentration, and laid the foundation for promoting the chemisorption process in the fixation of heavy metals. In combination with the Er (environmental risk factors), adding all three adsorbents reduced Ri (Risk index). Among them, Ca-Al (EG) at 3% had the best effect on Ri. 3% Ca–Al (EG) reduced the Er value of Ni by 49.02%. 5% Ca–Al (EG) reduced the Er value of Cr by 86.01%. 5% Ca–Al (UM) had the best effect on Mn, with a reduction of 46.13%. The addition of 10% Ca–Al (UM) reduced Er of Ni by 50.43%. Considering the practical application in coal-fired power plants, Ca-Al(EG), which exhibits a higher fixation rate at small additions, is more suitable.

Novel β-CdSnO3-SnO2 nanorod-like heterostructure materials for enhancing n-butanol sensing

n-butanol detection is crucial to environmental protection and mankind’s health because of its toxicity and irritation to the respiratory system. Mono-metal oxide semiconductors (such as SnO2) often face disadvantages such as low sensitivity, insufficient selectivity, and a high detection limit. Constructing heterojunctions has been considered an efficient way to enhance the performance of MOS gas sensors. This work presents the synthesis of a series of β-CdSnO3-SnO2 nanorod-like heterostructures with good n-butanol sensitivity using a hydrothermal and post-calcination approach. The optimized CSO/SO-8 shows the highest response value about 90–100 ppm n-butanol at 190 °C, which is 15 times greater than that of SnO2, and 6.5 times more than that of β-CdSnO3. Meanwhile, the CSO/SO-8 also exhibits a short response and recovery time (1–2 s/63 s). More importantly, the detection limit is reduced to ppb level (50 ppb). The improved gas-sensitive properties can be explained by the formation of n-n heterojunctions between β-CdSnO3 and SnO2, which increases the content of chemisorbed oxygen, thus enhancing the performance of the gas-sensitive. Our work not only provides a material with n-n heterostructures but also the strategy for constructing heterojunctions to improve gas-sensitive properties.

Preparation of Ni-B/MgAl2O4 catalysts for hydrogen production via steam reforming of methane

In this paper, a series of B doped Ni/MgAl2O4 catalysts for hydrogen production via steam reforming of methane (SRM) were prepared, and their catalytic activities and stability were evaluated. The characterization of XRD, XPS, TPR, BET, TPO, and TEM revealed that the addition of B could promote Ni dispersion, which lead to the reduce of Ni particle size. 0.5 wt% B was incorporated into Ni/MgAl2O4 would increase Ni particle dispersion rate from 11.2% to 14.8%, which caused Ni particle average size was decreased from 8.78 to 6.96 nm. At the same time, 0.5% B doped would increase the chemisorbed oxygen content of the catalyst, and more oxygen vacancies were formed. Thus, Ni particles sintering and carbon deposition during SRM was suppressed, and the catalytic activity and stability were promoted. Ni-B0.5/MgAl2O4 could achieve 90.2% methane conversion rate and 85% H2 yield under 700 °C with a WHSV of 36,000 mL·(gh)−1 during SRM process, and only a marginal reduction (2%) of methane conversion rate was observed after 48 h reaction. The total carbon content on the used Ni-B0.5/MgAl2O4 catalyst was approximately 0.031 gc∙gcat−1, which was three times lower than that of Ni/MgAl2O4. However, the excess B doping into Ni/MgAl2O4 had a negative effect on the catalytic activity and stability.

Plasma-catalytic synergistic oxidation of NO in the non-thermal plasma system: Insight into the active sites effect

Superoxide radicals-dominated oxidation plays a crucial role in the removal of NOx in gas treatment schemes, especially in the catalytic oxidation of NO at room temperature. However, the specific mechanism underlying radical oxidation processes remains unclear. In this study, a series of transitional metal (Mn, Co, Cr) catalysts anchored on graphitic carbon nitride (g-C3N4) were prepared and then introduced into non-thermal plasma (NTP) system to produce highly reactive superoxide free radicals (•O2-) for deep oxidation of NO. Experimental results revealed that the optimized CrCN catalyst, in combination with the NTP technique, exhibited an impressive oxidation efficiency of up to 100 %, which was 10 % and 30 % higher than that of MnCN and CoCN, respectively. Moreover, it was 1.56 times higher than that of NTP alone, indicating a synergistic effect of the NTP system and catalysis. The characterization results demonstrated that CrCN catalyst, with higher specific surface area and smaller grain sizes, was beneficial to increase the chemisorbed oxygen content and produce superoxide free radicals, which were proved by XPS, ESR technologies. Furthermore, the possible catalytic mechanism was proposed, which provided a basis for further understanding of the catalytic oxidation activity.

Wireless Gas Sensor Based on the Mesoporous ZnO-SnO2 Heterostructure Enables Ultrasensitive and Rapid Detection of 3-Methylbutyraldehyde.

Achieving ultrasensitive and rapid detection of 3-methylbutyraldehyde is crucial for monitoring chemical intermediate leakage in pharmaceutical and chemical industries as well as diagnosing ventilator-associated pneumonia by monitoring exhaled gas. However, developing a sensitive and rapid method for detecting 3-methylbutyraldehyde poses challenges. Herein, a wireless chemiresistive gas sensor based on a mesoporous ZnO-SnO2 heterostructure is fabricated to enable the ultrasensitive and rapid detection of 3-methylbutyraldehyde for the first time. The mesoporous ZnO-SnO2 heterostructure exhibits a uniform spherical shape (∼79 nm in diameter), a high specific surface area (54.8 m2 g-1), a small crystal size (∼4 nm), and a large pore size (6.7 nm). The gas sensor demonstrates high response (18.98@20 ppm), short response/recovery times (13/13 s), and a low detection limit (0.48 ppm) toward 3-methylbutyraldehyde. Furthermore, a real-time monitoring system is developed utilizing microelectromechanical systems gas sensors. The modification of amorphous ZnO on the mesoporous SnO2 pore wall can effectively increase the chemisorbed oxygen content and the thickness of the electron depletion layer at the gas-solid interface, which facilitates the interface redox reaction and enhances the sensing performance. This work presents an initial example of semiconductor metal oxide gas sensors for efficient detection of 3-methylbutyraldehyde that holds great potential for ensuring safety during chemical production and disease diagnosis.

Enhancement of low-temperature activity of γ-Fe2O3-modified V2O5-MoO3/TiO2 catalysts for selective catalytic reduction of NOx with NH3

In this study, a series of γ-Fe2O3-modified V2O5-MoO3/TiO2 (VMT) catalysts was prepared by wet impregnation method. The γ-Fe2O3-modified catalysts exhibited excellent catalytic performance, and 1.25 wt% γ-Fe2O3 content improved the deNOx efficiency at 150 °C from 54% (unmodified VMT catalyst) to 84% (modified catalyst). BET, XRD, XPS, NH3-TPD, H2-TPR, and in situ DRIFTs were employed to characterize the physicochemical properties and reaction mechanisms of the catalysts. The introduction of γ-Fe2O3 increased the V5+/V4+ ratio, surface chemisorbed oxygen content, redox ability, and a number of acid sites in the prepared catalysts. XPS confirmed the addition of γ-Fe2O3 introduced new charge transfer pathways (Fe3+/Fe2+ ↔ V5+/V4+). In situ DRIFTs suggested that the addition of γ-Fe2O3 to the catalyst significantly increased the adsorption capacity of catalyst for NH3 and NOx, while also exerting a strong activating effect on the adsorbed NH3. Furthermore, selective catalytic reduction over the VMT and 5PEG@1.25Fe-VMT catalysts followed the Eley-Rideal (E-R) mechanism. At temperatures above 200 °C, the 5PEG@1.25Fe-VMT catalyst also followed the Langmuir-Hinshelwood (L-H) mechanism.

Influence of organic sulfur gas-phase sulfation on the NH3-SCR activity of CeO2 catalyst: The competitive adsorption and conversion of CS2 and COS at a low hydrolysis temperature

In this study, a simplified approach is proposed to realize the gas-phase sulfation of CS2 or/and COS at the hydrolysis temperature for further facilitating the NH3-SCR activity of CeO2 in diverse conditions. A low-temperature oxidation conversion process for the adsorbed CS2 or COS on cubic fluorite CeO2 surface is developed. It is found that the gas-phase sulfation of organic CS2 or/and COS at 50 °C enhances the mobility of lattice oxygen of cubic fluorite CeO2 and the concentration of oxygen defects for the sulfated CeO2 catalyst, but the kinds of organic COS/CS2 can regulate the formed types and quality of sulfur-containing species on the catalyst surfaces during the gas-phase sulfation. and the formed sulfates under the gas-phase sulfation of CS2 are more active than those of COS, and CeO2-CS2-50 °C-3 h presents the best mobility of lattice oxygen, the largest concentration of adsorbed oxygen and the best NH3-SCR activity. Furthermore, the competitive adsorption and conversion of CS2 and COS is disadvantageous for the formation of oxygen vacancies on the catalyst surfaces compared to single CS2 or COS. However, the long-time durability testing coupling re-cycle experiments can optimize the oxygen vacancy defects and increase the concentration of chemisorbed oxygen of the sulfated CeO2-CS2 + COS-50 °C-24 h catalyst via optimizing the oxidization of sulfur element to sulfur oxides or/and sulfates, thereby improves its NH3-SCR activity. And the sulfated CeO2 catalyst by the gas-phase sulfation of organic COS + CS2 presents a good stability for NH3-SCR reaction. This study specifies a novel approach to simplify the gas-phase sulfation process of CeO2 catalyst, which is valuable in promotion of the NH3-SCR activity of CeO2 and reduction of cost in experimental procedures.

High response ZnO gas sensor derived from Tb@Zn-MOFs to acetic acid under UV excitation

As an n-type metal oxide semiconductor with a wide band gap (3.37 eV), ZnO has been widely used as gas sensors, but pure ZnO gas sensors suffer from low sensitivity. In this work, Zn-metal organic frameworks (Zn-MOFs) were synthesized by introducing H3BTC and H2ABDC as organic ligands, and then the Zn-MOFs were combined with Tb and calcined at 530 ℃ to obtain the derived oxides named as Tb@ZnO-1 and Tb@ZnO-2, respectively, in order to improve the gas sensitivity. Meanwhile, the microstructures and gas sensing properties of the two MOFs and their derivatives were characterized. Interestingly, the Zn-ABDC MOFs were observed as plush spherical microspheres assembled from nanowires, more possibly favorable for gas adsorption. In fact, prominent oxygen defects and chemisorbed oxygen content were found in the derivative Tb@ZnO-2. As a result, it exhibited good gas-sensitive properties and selectivity towards acetic acid, with a high response value of 47.30 at 240 ℃ for 100 ppm acetic acid gas and a very short response time (1 s), and the response value increased to 77.80 under UV excitation. The gas-sensitive mechanism and UV excitation mechanism are discussed.

Co-based defect-rich nanoarchitectonics with biomass carbon materials catalysts for CH4–CO2 reforming

The synthesis and utilization of defect-rich biomass carbon catalysts with varying Co concentrations and incorporated Ce in CH4-CO2 reforming were investigated. The catalytic performance of these catalysts was found to increase with higher Co content, reaching its optimum at a Co concentration of 20 %. The presence of Ce as a promoter improved the utilization of Co precursors and enhanced the dispersion of Co sites at defective structures on the catalyst surface. The confined space within the defective structures restricted the growth of Co particles, resulting in smaller and more uniformly dispersed Co particles on the catalyst surface. Additionally, the introduction of Ce species influenced the oxygen environment on the catalyst surface. XPS analysis confirmed that the addition of Ce led to an increase in the chemisorbed oxygen content, enhancing the catalyst's ability to activate CO2. The increased percentage of chemisorbed oxygen, coupled with improved CO2 activation capacity, contributed to the Co-Ce bimetallic catalyst's ability to resist carbon deposition. The Co-Ce bimetallic catalyst demonstrated exceptional stability and performance in CH4-CO2 reforming due to its enhanced metal dispersion, reduced metal particle size, and improved CO2 activation capacity. The incorporation of Ce as a promoter played a crucial role in achieving these desirable catalytic properties.

MOF-derived In2O3 nanotubes modified by r-GO for highly sensitive NOx detection at room temperature

MIL-68(In)-derived hollow tubular In2O3 compound with reduced graphite oxide (r-GO) is synthesized by solvothermal method. The In2O3/r-GO gas sensor is utilized for NOx detection at room temperature. Notably, the In2O3/r-GO achieved ultra-high response performance (2761) and fast response/recovery time (210/36s) for 100 ppm NOx than In2O3 (19.3, 345/200s). Meanwhile, the In2O3/r-GO sensor exhibits good selectivity and repeatability for NOx. The mechanism of NOx adsorption onto the material surface is investigated by DRIFT. The synergistic effect of In2O3 and r-GO is responsible for the improved gas-sensitive performance. The high surface area of In2O3/r-GO composites can provide more adsorption sites for the target gas. The excellent electron transport capability of r-GO nanosheets can reduce the response/recovery time. In addition, the formed heterogeneous structure increases the chemisorbed oxygen content, which promotes the response value. Therefore, In2O3/r-GO gas sensors show promising applications for monitoring NOx.

Enhanced Activity of Cerium‐Doped Co−Cr−O Composite Catalyst in Selective Catalytic Reduction of NO with NH3

AbstractCobalt‐chromium oxide catalyst and cerium‐doped cobalt‐chromium oxide catalyst were prepared by the coprecipitation method. The doping effect of Ce on the catalyst for selective catalytic reduction of NO with NH3 was investigated. Compared to Cobalt‐chromium oxide catalyst, the doping of Ce improved the catalytic activity and water and sulfur resistance of the catalyst. The doping of Ce significantly changed the surface morphology, reduced the crystallinity and increased the specific surface area of the catalyst. The large specific surface area of the catalyst facilitated the high dispersion of the acidic sites and promoted the adsorption and desorption of NH3. The doping of Ce increased the chemisorbed oxygen content and the number of acidic sites, enhancing the SCR activity of the catalyst. In addition, the doping of Ce increased the percentage of Co3+ and changed the ionic state of Cr, promoting the interaction between metal ions.

Heterojunctions on Ta2O5@MWCNT for Ultrasensitive Ethanol Sensing at Room Temperature.

Heterojunctions of Ta2O5 and multiwalled carbon nanotubes (MWCNTs) have been successfully synthesized by a facile and cost-effective hydrothermal method, with a super thin and uniform Ta2O5 shell wrapped around the MWCNT. The combination of Ta2O5 and MWCNTs at the interface not only modifies the morphology but also forms the p-n heterojunction, which contributes to the reconstruction of band structure, as well as the low resistance of matrix and highly chemisorbed oxygen content. The Ta2O5@MWCNT p-n heterojunction exhibits ultrasensitive performance to ethanol at room temperature, with a response of 3.15 toward 0.8 ppm ethanol and a detection limit of 0.173 ppm. The sensor has a high reproducibility at various concentrations of ethanol, superior selectivity to other gases, and long-term stability. The strategy of hybriding metal oxide semiconductors with MWCNT promises to provide a feasible and further developable pathway for high-performance room-temperature gas sensors.

Construction of Pt/Ce-In2O3 hierarchical microspheres for superior triethylamine detection at low temperature

Triethylamine (TEA) is a typical pollution in chemical industry and Corrupt markers of aquatic products. TEA emissions have a serious impact on human health, industrial production and food safety. In this study, hierarchical flower-like Pt-loaded/Ce-doped In2O3 microspheres are synthesized via simple hydrothermal and in-situ reduction methods. The triethylamine (TEA) sensing measurements display the 0.5Pt-3CeIn gas sensor exhibits high sensitivity (Ra/Rg = 900–100 ppm triethylamine), ultra-low optimal working temperature (100 ℃), enhanced responding and recovering speed (158/45 s) and excellent selectivity towards different target gases (ethanol, acetone, xylene, methanol, nitrogen dioxide and methane) including amine (response towards 50 ppm NH3 is lower than 10). The TEA detection limit is as low as 5 ppb and the sensor exhibits a wide TEA detection range. The introduction of Pt and Ce components into In2O3 effectively reduces the operating temperature, promotes the chemisorbed oxygen content (18.14 %) and wildly decreases the band gap (2.97 eV). The gas sensing mechanism of Pt/Ce-In2O3, which is dominated by electronic and chemical sensitization of Pt, catalytic function of Ce dopants and the functional interface between Pt nanoparticles and Ce-doped In2O3 microspheres, is proposed. This work as well testifies the feasibility for multi-components cooperative optimization of MOS in gas sensing applications.

Synergistic removal of NO and soot by Fe-W-Zr-ZSM-5 catalysts in a wide temperature window

Obtaining the synergistic catalytic removal of NO and soot is a highlight topic as both NO and soot are the main pollutants from diesel engine. However, synergistic catalytic removal is still very difficult because the temperature window varies with the traditional SCR catalyst of NO at narrow temperature of 300–450 ℃ and the oxidation temperature of soot at high temperature of 500–700 ℃. Therefore, based on W-Zr-ZSM-5 catalyst, a series of M-W-Zr-ZSM-5 (M = Cu, Fe or Nb) catalysts were prepared by sol–gel method to investigate the synergistic catalytic removal of NO and soot, which emitted from diesel engine at the same time. The results showed that Fe-W-Zr-ZSM-5 catalyst exhibited the best NH3-SCR reaction activity and oxidizing performance of soot among the catalysts, with more than 90 % NO conversion in the temperature range of 320 ℃ to 580 ℃ and completely oxidization of soot in the temperature range of 432 ℃ to 543 ℃. The results of XRD, BET, XPS and Raman spectrum indicated that there was strong interaction between W and Fe, promoting the formation of W5+ and W = O species, thereby increasing the content of chemisorbed oxygen, the amount of surface acid sites and redox capacity of the catalysts. Meanwhile, the redox capacity of Fe-W-Zr-ZSM-5 was responsible for the improvement of NH3-SCR activity and the oxidation of soot at low temperature. Fe-W-Zr-ZSM-5 catalyst demonstrated to be a promising material to synergistic remove NO and soot.

Investigation of Co-doped Mn oxide catalyst for NH3-SCR activity and SO2/H2O resistance

A series of Co-doped Mn oxide catalysts with different Co/Mn molar ratios were prepared by co-precipitation method, which was systematically characterized by XRD, SEM, H2-TPR and NH3-TPD etc. Co-doped Mn oxide catalysts are evaluated for NH3-SCR activity and resistance to SO2 and/or H2O, and the Co(1)-MnOx catalyst with Mn/Co molar ratio of 1:1 performs the best catalytic performance, which achieved higher than 90% NOx conversion in the temperature range of 100−275 °C and possessed better SO2 and H2O resistance. The Co(1)-MnOx catalyst presented a sphere-like structure possessing a relatively large surface area. Doping of cobalt greatly improved the high-valent metal ions and chemisorbed oxygen content of Co(1)-MnOx catalyst surface, and the catalyst possessed abundant active species and acid sites and apparent activation energy of the catalyst was reduced, which makes Co(1)-MnOx a highly effective NH3-SCR catalyst.

Resource utilization of high-concentration SO2 for sulfur production over La-Ce-Ox composite oxide catalyst.

Sulfur dioxide is one of the main causes of air pollution such as acid rain and photochemical smog, and its pollution control and resource utilization have become important research directions. La2O3 was incorporated into CeO2 to enhance the surface basicity of La-Ce-Ox catalyst and increase the concentration of chemisorbed oxygen, thereby promoting the improvement of catalytic performance of SO2 reduction by CO. Results have showed that the incorporation of La2O3 would not only increase the concentration of chemisorbed oxygen and hydroxyl on the catalyst surface, but also increase the basicity of the catalyst, thereby facilitating the adsorption of SO2 on the catalyst surface. The 12%La-Ce-Ox was the optimal catalyst, and its SO2 conversion at 350-400 ℃ reached close to 100%, and the sulfur yield at this temperature range was higher than 93%. Finally, according to the in situ infrared diffuse reflectance spectrum, it was found that the main reaction intermediates of 12%La-Ce-Ox in the catalytic reduction of SO2 were weakly adsorbed sulfate, SO32-, non-coordinating CO32-, monodentate carbonate, and CO, so the catalytic reaction followed the L-H and E-R mechanisms simultaneously.

In-situ growth of Co/Zn bimetallic MOF on GO surface to prepare GO supporting Co@C single-atom catalyst for Hg0 oxidation

Oxidation of Hg0 to Hg2+ is an efficient way to remove Hg0 from flue gas. Chemisorbed oxygen as the main active site plays an important role in Hg0 oxidation process. Single-atom catalyst has an excellent ability of transforming gaseous oxygen into chemisorbed oxygen. In the present work, graphene oxide (GO) was used as support to in-situ grow Co/Zn bimetallic MOF on GO surface. After pyrolysis, a GO supported Co@C single-atom catalyst was obtained. SEM and TEM results show that GO supporting gives a high dispersion for calcined MOF particles. HAADF-STEM results prove that most of the Co atoms in calcined MOF particles stay as single-atom status. EXAFS indicated that the Co atoms in the catalyst was coordinated with N, and the coordination was dominated by CoN2. CoN2 can capture and activate gaseous oxygen forming more chemisorbed oxygen. Thanks to the high dispersion of calcined MOF and higher chemisorbed oxygen concentration, the Hg0 oxidation efficiency of the obtained catalyst (Co2.5-SAs@NC/GO-1) can reach above 90 % in the temperature range of 120–180 °C with 0.075 g loading amount at the GHSV of 180, 000 h−1. The probable reaction pathway was analyzed by an adsorption–desorption experiment and XPS over the used and regenerated Co2.5-SAs@NC/GO-1.

Effect of CeO2 and Pt introduction on the structure and performance of Fe2O3 for Hg0 removal

In this work, the thermal stability and catalytic activity of Fe2O3 catalyst for Hg0 oxidation were improved by the introduction of CeO2 and Pt. During high-temperature calcination at 400 °C, the mesoporous structure of Pt/CeO2/Fe2O3 remained stable, and it also retained higher specific surface area and lower average pore size than Fe2O3. The X-ray diffraction, transmission electron microscopy, and thermal gravimetric-differential scanning calorimetry results revealed that the modification of CeO2 and Pt retarded the crystallization and growth of Fe2O3 grains during high-temperature calcination, limiting Fe2O3 particles to a smaller size. Temperature-programmed desorption experiments showed that Hg0 adsorption of Pt/CeO2/Fe2O3 was promoted. In addition, X-ray photoelectron spectroscopy spectra suggested that adding CeO2 and Pt also increased the content of chemisorbed oxygen and transformed Fe2O3 into an electron-rich state, which consequently improved its catalytic performance for Hg0 oxidation.

A comprehensive optimization of the sensitivity of CdS/CdIn2S4 composites to triethylamine gas

The physical and chemical properties of CdIn2S4 can be effectively regulated by changing the composition and phase structure to present a rich diversity, making it a potential new gas sensing material. However, CdIn2S4 has the characteristics of low carrier mobility and difficult separation of electrons and holes, which greatly hinders its development in the fields of gas sensing and catalysis. In this work, a sulfur-vacancy-rich CdS/CdIn2S4 heterojunction composite was constructed by a one-step hydrothermal method for gas sensing, and the built-in electric field was used to effectively promote the separation and transfer of charges. Moreover, the introduction of sulfur vacancies increases the content of chemisorbed oxygen, which provides more reactive sites for the target gas, thereby realizing the improvement of gas sensing performance. Compared with the CdIn2S4 sensor, the CdS/CdIn2S4 sensor exhibited higher response to triethylamine (10 ppm-32.5), faster response/recovery time (3 s/256 s) and achieved a lower limit of detection at the ppb level (500 ppb-5.2). This work provides a new solution for real-time monitoring of low-concentration triethylamine gas.

Effect of Nb(V) doping on the Structure and Oxygen Chemisorption on Nanocrystalline TiO2

AbstractThis work is devoted to the study of the effect of niobium doping on the structural characteristics and chemisorption of oxygen on the TiO2 surface. Pure and Nb doped TiO2 was obtained by flame spray pyrolysis and characterized using SEM, TEM, XRD, low‐temperature nitrogen adsorption XRF, XPS, TPR‐H2 methods. The introduction of niobium stabilizes the anatase phase, increases the specific surface area of TiO2 and the concentration of chemisorbed oxygen. By in situ conductivity measurements depending on the oxygen partial pressure, it is shown that an increase in the Nb concentration leads to the growth of the fraction of chemisorbed oxygen with a lower effective charge.