Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Article Types

Countries / Regions

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Search Results (1,395)

Search Parameters:
Keywords = O vacancies

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
14 pages, 2584 KiB  
Article
Enhanced Catalytic Ozonation of Formaldehyde over MOFs- Derived MnOx Catalysts with Diverse Morphologies: The Role of Oxygen Vacancies
by Yulin Sun, Yiwei Zhang, Yong He, Wubin Weng, Yanqun Zhu and Zhihua Wang
Catalysts 2025, 15(8), 752; https://doi.org/10.3390/catal15080752 - 6 Aug 2025
Abstract
Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnOx catalysts with [...] Read more.
Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnOx catalysts with diverse morphologies (rod-like, flower-like, slab-like) via the pyrolysis of MOF precursors, and the as-prepared MnOx catalysts demonstrated superior performance compared to the one prepared using the co-precipitation method. MnOx-II, with a flower-like structure, exhibited excellent activity for formaldehyde (HCHO) catalytic ozonation at room temperature, reaching complete HCHO conversion at O3/HCHO of 1.5 and more than 90% CO2 selectivity at an O3/HCHO ratio of 2.5. On the basis of various characterization methods, it was clarified that the enhanced catalytic performance of MnOx-II benefited from its larger BET surface area, abundant oxygen vacancies, better redox ability at lower temperature, and more Lewis acid sites. The H2O resistance and stability tests were also conducted. Furthermore, DFT calculations substantiated the enhanced adsorption of HCHO and O3 on oxygen vacancies, while in–situ DRIFTS measurements elucidated the degradation pathway of HCHO during catalytic ozonation through detected intermediates. Full article
(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)
Show Figures

Graphical abstract

14 pages, 4225 KiB  
Article
DFT Investigation into Adsorption–Desorption Properties of Mg/Ni-Doped Calcium-Based Materials
by Wei Shi, Renwei Li, Xin Bao, Haifeng Yang and Dehao Kong
Crystals 2025, 15(8), 711; https://doi.org/10.3390/cryst15080711 - 3 Aug 2025
Viewed by 139
Abstract
Although concentrated solar power (CSP) coupled with calcium looping (CaL) offers a promising avenue for efficient thermal chemical energy storage, calcium-based sorbents suffer from accelerated structural degradation and decreased CO2 capture capacity during multiple cycles. This study used Density Functional Theory (DFT) [...] Read more.
Although concentrated solar power (CSP) coupled with calcium looping (CaL) offers a promising avenue for efficient thermal chemical energy storage, calcium-based sorbents suffer from accelerated structural degradation and decreased CO2 capture capacity during multiple cycles. This study used Density Functional Theory (DFT) calculations to investigate the mechanism by which Mg and Ni doping improves the adsorption/desorption performance of CaO. The DFT results indicate that Mg and Ni doping can effectively reduce the formation energy of oxygen vacancies on the CaO surface. Mg–Ni co-doping exhibits a significant synergistic effect, with the formation energy of oxygen vacancies reduced to 5.072 eV. Meanwhile, the O2− diffusion energy barrier in the co-doped system was reduced to 2.692 eV, significantly improving the ion transport efficiency. In terms of CO2 adsorption, Mg and Ni co-doping enhances the interaction between surface O atoms and CO2, increasing the adsorption energy to −1.703 eV and forming a more stable CO32− structure. For the desorption process, Mg and Ni co-doping restructured the CaCO3 surface structure, reducing the CO2 desorption energy barrier to 3.922 eV and significantly promoting carbonate decomposition. This work reveals, at the molecular level, how Mg and Ni doping optimizes adsorption–desorption in calcium-based materials, providing theoretical guidance for designing high-performance sorbents. Full article
(This article belongs to the Special Issue Performance and Processing of Metal Materials)
Show Figures

Figure 1

17 pages, 1801 KiB  
Article
The Influence of Accumulated Radiolysis Products on the Mechanisms of High-Temperature Degradation of Two-Component Lithium-Containing Ceramics
by Inesh E. Kenzhina, Saulet Askerbekov, Artem L. Kozlovskiy, Aktolkyn Tolenova, Sergei Piskunov and Anatoli I. Popov
Ceramics 2025, 8(3), 99; https://doi.org/10.3390/ceramics8030099 (registering DOI) - 3 Aug 2025
Viewed by 313
Abstract
One of the advantages of the EPR spectroscopy method in assessing structural defects caused by irradiation is the fact that using this method it is possible to determine not only the concentration dependences of the defect structure but to also establish their type, [...] Read more.
One of the advantages of the EPR spectroscopy method in assessing structural defects caused by irradiation is the fact that using this method it is possible to determine not only the concentration dependences of the defect structure but to also establish their type, which is not possible with methods such as X-ray diffraction or scanning electron microscopy. Based on the data obtained, the role of variation in the ratio of components in Li4SiO4–Li2TiO3 ceramics on the processes of softening under high-dose irradiation with protons simulating the accumulation of hydrogen in the damaged layer, as well as the concentration of structural defects in the form of oxygen vacancies and radiolysis products on the processes of high-temperature degradation of ceramics, was determined. It was found that the main changes in the defect structure during the prolonged thermal exposure of irradiated samples are associated with the accumulation of oxygen vacancies, the density of which was estimated by the change in the intensity of singlet lithium, characterizing the presence of E-centers. At the same time, it was found that the formation of interphase boundaries in the structure of Li4SiO4–Li2TiO3 ceramics leads to the inhibition of high-temperature degradation processes in the case of post-radiation thermal exposure for a long time. Also, during the conducted studies, the role of thermal effects on the structural damage accumulation rate in Li4SiO4–Li2TiO3 ceramics was determined in the case when irradiation is carried out at different temperatures. During the experiments, it was determined that the main contribution of thermal action in the process of proton irradiation at a fluence of 5 × 1017 proton/cm2 is an increase in the concentration of radiolysis products, described by changes in the intensities of spectral maxima, characterized by the presence of defects such as ≡Si–O, SiO43− and Ti3+ defects. Full article
(This article belongs to the Special Issue Advances in Ceramics, 3rd Edition)
Show Figures

Figure 1

26 pages, 5007 KiB  
Article
Copper-Enhanced NiMo/TiO2 Catalysts for Bifunctional Green Hydrogen Production and Pharmaceutical Pollutant Removal
by Nicolás Alejandro Sacco, Fernanda Albana Marchesini, Ilaria Gamba and Gonzalo García
Catalysts 2025, 15(8), 737; https://doi.org/10.3390/catal15080737 - 1 Aug 2025
Viewed by 258
Abstract
This study presents the development of Cu-doped NiMo/TiO2 photoelectrocatalysts for simultaneous green hydrogen production and pharmaceutical pollutant removal under simulated solar irradiation. The catalysts were synthesized via wet impregnation (15 wt.% total metal loading with 0.6 wt.% Cu) and thermally treated at [...] Read more.
This study presents the development of Cu-doped NiMo/TiO2 photoelectrocatalysts for simultaneous green hydrogen production and pharmaceutical pollutant removal under simulated solar irradiation. The catalysts were synthesized via wet impregnation (15 wt.% total metal loading with 0.6 wt.% Cu) and thermally treated at 400 °C and 900 °C to investigate structural transformations and catalytic performance. Comprehensive characterization (XRD, BET, SEM, XPS) revealed phase transitions, enhanced crystallinity, and redistribution of redox states upon Cu incorporation, particularly the formation of NiTiO3 and an increase in oxygen vacancies. Crystallite sizes for anatase, rutile, and brookite ranged from 21 to 47 nm at NiMoCu400, while NiMoCu900 exhibited only the rutile phase with 55 nm crystallites. BET analysis showed a surface area of 44.4 m2·g−1 for NiMoCu400, and electrochemical measurements confirmed its higher electrochemically active surface area (ECSA, 2.4 cm2), indicating enhanced surface accessibility. In contrast, NiMoCu900 exhibited a much lower BET surface area (1.4 m2·g−1) and ECSA (1.4 cm2), consistent with its inferior photoelectrocatalytic performance. Compared to previously reported binary NiMo/TiO2 systems, the ternary NiMoCu/TiO2 catalysts demonstrated significantly improved hydrogen production activity and more efficient photoelectrochemical degradation of paracetamol. Specifically, NiMoCu400 showed an anodic peak current of 0.24 mA·cm−2 for paracetamol oxidation, representing a 60% increase over NiMo400 and a cathodic current of −0.46 mA·cm−2 at −0.1 V vs. RHE under illumination, nearly six times higher than the undoped counterpart (–0.08 mA·cm−2). Mott–Schottky analysis further revealed that NiMoCu400 retained n-type behavior, while NiMoCu900 exhibited an unusual inversion to p-type, likely due to Cu migration and rutile-phase-induced realignment of donor states. Despite its higher photosensitivity, NiMoCu900 showed negligible photocurrent, confirming that structural preservation and surface redox activity are critical for photoelectrochemical performance. This work provides mechanistic insight into Cu-mediated photoelectrocatalysis and identifies NiMoCu/TiO2 as a promising bifunctional platform for integrated solar-driven water treatment and sustainable hydrogen production. Full article
(This article belongs to the Section Electrocatalysis)
Show Figures

Figure 1

14 pages, 4979 KiB  
Article
Oxygen Vacancy-Engineered Ni:Co3O4/Attapulgite Photothermal Catalyst from Recycled Spent Lithium-Ion Batteries for Efficient CO2 Reduction
by Jian Shi, Yao Xiao, Menghan Yu and Xiazhang Li
Catalysts 2025, 15(8), 732; https://doi.org/10.3390/catal15080732 - 1 Aug 2025
Viewed by 276
Abstract
Accelerated industrialization and surging energy demands have led to continuously rising atmospheric CO2 concentrations. Developing sustainable methods to reduce atmospheric CO2 levels is crucial for achieving carbon neutrality. Concurrently, the rapid development of new energy vehicles has driven a significant increase [...] Read more.
Accelerated industrialization and surging energy demands have led to continuously rising atmospheric CO2 concentrations. Developing sustainable methods to reduce atmospheric CO2 levels is crucial for achieving carbon neutrality. Concurrently, the rapid development of new energy vehicles has driven a significant increase in demand for lithium-ion batteries (LIBs), which are now approaching an end-of-life peak. Efficient recycling of valuable metals from spent LIBs represents a critical challenge. This study employs conventional hydrometallurgical processing to recover valuable metals from spent LIBs. Subsequently, Ni-doped Co3O4 (Ni:Co3O4) supported on the natural mineral attapulgite (ATP) was synthesized via a sol–gel method. The incorporation of a small amount of Ni into the Co3O4 lattice generates oxygen vacancies, inducing a localized surface plasmon resonance (LSPR) effect, which significantly enhances charge carrier transport and separation efficiency. During the photocatalytic reduction of CO2, the primary product CO generated by the Ni:Co3O4/ATP composite achieved a high production rate of 30.1 μmol·g−1·h−1. Furthermore, the composite maintains robust catalytic activity even after five consecutive reaction cycles. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis in Air Pollution Control)
Show Figures

Figure 1

20 pages, 3979 KiB  
Article
Theoretical Study of CO Oxidation on Pt Single-Atom Catalyst Decorated C3N Monolayers with Nitrogen Vacancies
by Suparada Kamchompoo, Yuwanda Injongkol, Nuttapon Yodsin, Rui-Qin Zhang, Manaschai Kunaseth and Siriporn Jungsuttiwong
Sci 2025, 7(3), 101; https://doi.org/10.3390/sci7030101 - 1 Aug 2025
Viewed by 257
Abstract
Carbon monoxide (CO) is a major toxic gas emitted from vehicle exhaust, industrial processes, and incomplete fuel combustion, posing serious environmental and health risks. Catalytic oxidation of CO into less harmful CO2 is an effective strategy to reduce these emissions. In this [...] Read more.
Carbon monoxide (CO) is a major toxic gas emitted from vehicle exhaust, industrial processes, and incomplete fuel combustion, posing serious environmental and health risks. Catalytic oxidation of CO into less harmful CO2 is an effective strategy to reduce these emissions. In this study, we investigated the catalytic performance of platinum (Pt) single atoms doped on C3N monolayers with various vacancy defects, including single carbon (CV) and nitrogen (NV) vacancies, using density functional theory (DFT) calculations. Our results demonstrate that Pt@NV-C3N exhibited the most favorable catalytic properties, with the highest O2 adsorption energy (−3.07 eV). This performance significantly outperforms Pt atoms doped at other vacancies. It can be attributed to the strong binding between Pt and nitrogen vacancies, which contributes to its excellent resistance to Pt aggregation. CO oxidation on Pt@NV-C3N proceeds via the Eley–Rideal (ER2) mechanism with a low activation barrier of 0.41 eV for the rate-determining step, indicating high catalytic efficiency at low temperatures. These findings suggest that Pt@NV-C3N is a promising candidate for CO oxidation, contributing to developing cost-effective and environmentally sustainable catalysts. The strong binding of Pt atoms to the nitrogen vacancies prevents aggregation, ensuring the stability and durability of the catalyst. The kinetic modeling further revealed that the ER2 mechanism offers the highest reaction rate constants over a wide temperature range (273–700 K). The low activation energy barrier also facilitates CO oxidation at lower temperatures, addressing critical challenges in automotive and industrial pollution control. This study provides valuable theoretical insights for designing advanced single-atom catalysts for environmental remediation applications. Full article
Show Figures

Graphical abstract

14 pages, 3688 KiB  
Article
Oxygen-Vacancy Engineered SnO2 Dots on rGO with N-Doped Carbon Nanofibers Encapsulation for High-Performance Sodium-Ion Batteries
by Yue Yan, Bingxian Zhu, Zhengzheng Xia, Hui Wang, Weijuan Xu, Ying Xin, Qingshan Zhao and Mingbo Wu
Molecules 2025, 30(15), 3203; https://doi.org/10.3390/molecules30153203 - 30 Jul 2025
Viewed by 253
Abstract
The widespread adoption of sodium-ion batteries (SIBs) remains constrained by the inherent limitations of conventional anode materials, particularly their inadequate electronic conductivity, limited active sites, and pronounced structural degradation during cycling. To overcome these limitations, we propose a novel redox engineering approach to [...] Read more.
The widespread adoption of sodium-ion batteries (SIBs) remains constrained by the inherent limitations of conventional anode materials, particularly their inadequate electronic conductivity, limited active sites, and pronounced structural degradation during cycling. To overcome these limitations, we propose a novel redox engineering approach to fabricate oxygen-vacancy-rich SnO2 dots anchored on reduced graphene oxide (rGO), which are encapsulated within N-doped carbon nanofibers (denoted as ov-SnO2/rGO@N-CNFs) through electrospinning and subsequent carbonization. The introduction of rich oxygen vacancies establishes additional sodium intercalation sites and enhances Na+ diffusion kinetics, while the conductive N-doped carbon network effectively facilitates charge transport and mitigates SnO2 aggregation. Benefiting from the well-designed architecture, the hierarchical ov-SnO2/rGO@N-CNFs electrode achieves remarkable reversible specific capacities of 351 mAh g−1 after 100 cycles at 0.1 A g−1 and 257.3 mAh g−1 after 2000 cycles at 1.0 A g−1 and maintains 177 mAh g−1 even after 8000 cycles at 5.0 A g−1, demonstrating exceptional long-term cycling stability and rate capability. This work offers a versatile design strategy for developing high-performance anode materials through synergistic interface engineering for SIBs. Full article
Show Figures

Graphical abstract

18 pages, 2288 KiB  
Article
Defect Studies in Thin-Film SiO2 of a Metal-Oxide-Silicon Capacitor Using Drift-Assisted Positron Annihilation Lifetime Spectroscopy
by Ricardo Helm, Werner Egger, Catherine Corbel, Peter Sperr, Maik Butterling, Andreas Wagner, Maciej Oskar Liedke, Johannes Mitteneder, Michael Mayerhofer, Kangho Lee, Georg S. Duesberg, Günther Dollinger and Marcel Dickmann
Nanomaterials 2025, 15(15), 1142; https://doi.org/10.3390/nano15151142 - 23 Jul 2025
Viewed by 281
Abstract
This work investigates the impact of an internal electric field on the annihilation characteristics of positrons implanted in a 180(10)nm SiO2 layer of a Metal-Oxide-Silicon (MOS) capacitor, using Positron Annihilation Lifetime Spectroscopy (PALS). By varying the gate voltage, [...] Read more.
This work investigates the impact of an internal electric field on the annihilation characteristics of positrons implanted in a 180(10)nm SiO2 layer of a Metal-Oxide-Silicon (MOS) capacitor, using Positron Annihilation Lifetime Spectroscopy (PALS). By varying the gate voltage, electric fields up to 1.72MV/cm were applied. The measurements reveal a field-dependent suppression of positronium (Ps) formation by up to 64%, leading to an enhancement of free positron annihilation. The increase in free positrons suggests that vacancy clusters are the dominant defect type in the oxide layer. Additionally, drift towards the SiO2/Si interface reveals not only larger void-like defects but also a distinct population of smaller traps that are less prominent when drifting to the Al/SiO2 interface. In total, by combining positron drift with PALS, more detailed insights into the nature and spatial distribution of defects within the SiO2 network and in particular near the SiO2/Si interface are obtained. Full article
(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)
Show Figures

Figure 1

8 pages, 971 KiB  
Article
Mechanism of Topotactic Reduction-Oxidation Between Mg-Doped SrMoO3 Perovskites and SrMoO4 Scheelites, Utilized as Anode Materials for Solid Oxide Fuel Cells
by Vanessa Cascos, M. T. Fernández-Díaz and José Antonio Alonso
Materials 2025, 18(15), 3424; https://doi.org/10.3390/ma18153424 - 22 Jul 2025
Viewed by 224
Abstract
Recently, we have described SrMo1-xMgxO3-δ perovskites (x = 0.1, 0.2) as excellent anode materials for solid oxide fuel cells (SOFCs), with mixed ionic and electronic conduction (MIEC) properties. After depositing on the solid electrolyte, they were annealed for [...] Read more.
Recently, we have described SrMo1-xMgxO3-δ perovskites (x = 0.1, 0.2) as excellent anode materials for solid oxide fuel cells (SOFCs), with mixed ionic and electronic conduction (MIEC) properties. After depositing on the solid electrolyte, they were annealed for sintering at high temperatures (typically 1000 °C), giving rise to oxidized scheelite-type phases, with SrMo1-xMgxO4-δ (x = 0.1, 0.2) stoichiometry. To obtain the active perovskite phases, they were reduced again in the working anode conditions, under H2 atmosphere. Therefore, there must be an excellent reversibility between the oxidized Sr(Mo, Mg)O4-δ scheelite and the reduced Sr(Mo, Mg)O3-δ perovskite phases. This work describes the topotactical oxidation, by annealing at 400 °C in air, of the SrMo0.9Mg0.1O3-δ perovskite oxide. The characterization by X-ray diffraction (XRD) and neutron powder diffraction (NPD) was carried out in order to determine the crystal structure features. The scheelite oxides are tetragonal, space group I41/a (No. 88), whereas the perovskites are cubic, s.g. Pm-3m (No. 221). The Rietveld refinement of the scheelite phase from NPD data after annealing the perovskite at 400 °C and cooling it down slowly to RT evidences the absence of intermediate phases between perovskite and scheelite oxides, as well as the presence of oxygen vacancies in both oxidized and reduced phases, essential for their performance as MIEC oxides. The topotactical relationship between both crystal structures is discussed. Full article
Show Figures

Figure 1

20 pages, 18517 KiB  
Article
A Highly Sensitive Low-Temperature N-Butanol Gas Sensor Based on a Co-Doped MOF-ZnO Nanomaterial Under UV Excitation
by Yinzhong Liu, Xiaoshun Wei, Yun Guo, Lingchao Wang, Hui Guo, Qingjie Wang, Yiyu Qiao, Xiaotao Zhu, Xuechun Yang, Lingli Cheng and Zheng Jiao
Sensors 2025, 25(14), 4480; https://doi.org/10.3390/s25144480 - 18 Jul 2025
Viewed by 384
Abstract
Volatile organic compounds (VOCs) are presently posing a rather considerable threat to both human health and environmental sustainability. Among these, n-butanol is commonly identified as bringing potential hazards to environmental integrity and individual health. This study presents the creation of a highly sensitive [...] Read more.
Volatile organic compounds (VOCs) are presently posing a rather considerable threat to both human health and environmental sustainability. Among these, n-butanol is commonly identified as bringing potential hazards to environmental integrity and individual health. This study presents the creation of a highly sensitive n-butanol gas sensor utilizing cobalt-doped zinc oxide (ZnO) derived from a metal–organic framework (MOF). A series of x-Co/MOF-ZnO (x = 1, 3, 5, 7 wt%) nanomaterials with varying Co ratios were generated using the homogeneous co-precipitation method and assessed for their gas-sensing performances under a low operating temperature (191 °C) and UV excitation (220 mW/cm2). These findings demonstrated that the 5-Co/MOF-ZnO sensor presented the highest oxygen vacancy (Ov) concentration and the largest specific surface area (SSA), representing the optimal reactivity, selectivity, and durability for n-butanol detection. Regarding the sensor’s response to 100 ppm n-butanol under UV excitation, it achieved a value of 1259.06, 9.80 times greater than that of pure MOF-ZnO (128.56) and 2.07 times higher than that in darkness (608.38). Additionally, under UV illumination, the sensor achieved a rapid response time (11 s) and recovery rate (23 s). As a strategy to transform the functionality of ZnO-based sensors for n-butanol gas detection, this study also investigated potential possible redox reactions occurring during the detection process. Full article
(This article belongs to the Special Issue New Sensors Based on Inorganic Material)
Show Figures

Figure 1

16 pages, 8045 KiB  
Article
Modification of G-C3N4 by the Surface Alkalinization Method and Its Photocatalytic Depolymerization of Lignin
by Zhongmin Ma, Ling Zhang, Lihua Zang and Fei Yu
Materials 2025, 18(14), 3350; https://doi.org/10.3390/ma18143350 - 17 Jul 2025
Viewed by 315
Abstract
The efficient depolymerization of lignin has become a key challenge in the preparation of high-value-added chemicals. Graphitic carbon nitride (g-C3N4)-based photocatalytic system shows potential due to its mild and green characteristics over other depolymerization methods. However, its inherent defects, [...] Read more.
The efficient depolymerization of lignin has become a key challenge in the preparation of high-value-added chemicals. Graphitic carbon nitride (g-C3N4)-based photocatalytic system shows potential due to its mild and green characteristics over other depolymerization methods. However, its inherent defects, such as a wide band gap and rapid carrier recombination, severely limit its catalytic performance. In this paper, a g-C3N4 modification strategy of K⁺ doping and surface alkalinization is proposed, which is firstly applied to the photocatalytic depolymerization of the lignin β-O-4 model compound (2-phenoxy-1-phenylethanol). K⁺ doping is achieved by introducing KCl in the precursor thermal polymerization stage to weaken the edge structure strength of g-C3N4, and post-treatment with KOH solution is combined to optimize the surface basic groups. The structural/compositional evolution of the materials was analyzed by XRD, FTIR, and XPS. The morphology/element distribution was visualized by SEM-EDS, and the optoelectronic properties were evaluated by UV–vis DRS, PL, EIS, and transient photocurrent (TPC). K⁺ doping and surface alkalinization synergistically regulate the layered structure of the material, significantly increase the specific surface area, introduce nitrogen vacancies and hydroxyl functional groups, effectively narrow the band gap (optimized to 2.35 eV), and inhibit the recombination of photogenerated carriers by forming electron capture centers. Photocatalytic experiments show that the alkalinized g-C3N4 can completely depolymerize 2-phenoxy-1-phenylethanol with tunable product selectivity. By adjusting reaction time and catalyst dosage, the dominant product can be shifted from benzaldehyde (up to 77.28% selectivity) to benzoic acid, demonstrating precise control over oxidation degree. Mechanistic analysis shows that the surface alkaline sites synergistically optimize the Cβ-O bond breakage path by enhancing substrate adsorption and promoting the generation of active oxygen species (·OH, ·O2). This study provides a new idea for the efficient photocatalytic depolymerization of lignin and lays an experimental foundation for the interface engineering and band regulation strategies of g-C3N4-based catalysts. Full article
(This article belongs to the Section Catalytic Materials)
Show Figures

Figure 1

19 pages, 4331 KiB  
Article
Optimization of Grain Boundary Structure and Dielectric Properties in SrTiO3 Ceramics via Hot Isostatic Pressing
by Yilong Feng, Zhenya Lu, Ming Lv, Dan Qie and Zaiyun Long
Materials 2025, 18(14), 3301; https://doi.org/10.3390/ma18143301 - 13 Jul 2025
Viewed by 368
Abstract
This study fabricated SrTiO3 grain boundary layer ceramics using hot isostatic pressing (HIP), achieving a remarkably high dielectric constant of 60,350 and a superior breakdown strength of 1722 kV/m. Microstructural characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed [...] Read more.
This study fabricated SrTiO3 grain boundary layer ceramics using hot isostatic pressing (HIP), achieving a remarkably high dielectric constant of 60,350 and a superior breakdown strength of 1722 kV/m. Microstructural characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that HIP treatment significantly refined grain size uniformity and homogenized bismuth distribution at grain boundaries, thus enhancing the interfacial barrier effect. Probe-based impedance spectroscopy elucidated the dielectric behavior and conduction mechanisms of individual grain boundaries. HIP promotes the formation of interfacial barrier layers (IBLs), significantly improving electrical performance. Compared to untreated samples (average breakdown strength: 555 kV/m), HIP-processed ceramics exhibited a threefold enhancement in breakdown strength (1722 kV/m). The treated ceramic exhibited excellent temperature stability, with TCC ≤8% over −55 to 125 °C. The optimized dielectric properties stem from HIP-induced structural modifications, including reduced oxygen vacancy concentrations and homogenized electronic distribution at grain boundaries. These findings establish a quantitative correlation between HIP parameters, grain boundary restructuring, and macroscopic performance, providing critical insights for designing high-energy-density dielectric materials. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
Show Figures

Figure 1

16 pages, 4139 KiB  
Article
Engineering Hierarchical CuO/WO3 Hollow Spheres with Flower-like Morphology for Ultra-Sensitive H2S Detection at ppb Level
by Peishuo Wang and Xueli Yang
Chemosensors 2025, 13(7), 250; https://doi.org/10.3390/chemosensors13070250 - 11 Jul 2025
Viewed by 363
Abstract
Highly sensitive real-time detection of hydrogen sulfide (H2S) is important for human health and environmental protection due to its highly toxic properties. The development of high-performance H2S sensors remains challenging for poor selectivity, high limit detection and slow recovery [...] Read more.
Highly sensitive real-time detection of hydrogen sulfide (H2S) is important for human health and environmental protection due to its highly toxic properties. The development of high-performance H2S sensors remains challenging for poor selectivity, high limit detection and slow recovery from irreversible sulfidation. To solve these problems, we strategically prepared a layered structure of CuO-sensitized WO3 flower-like hollow spheres with CuO as the sensitizing component. A 15 wt% CuO/WO3 exhibits an ultra-high response (Ra/Rg = 571) to 10 ppm H2S (131-times of pure WO3), excellent selectivity (97-times higher than 100 ppm interference gas), and a low detection limit (100 ppb). Notably, its fast response (4 s) is accompanied by full recovery within 236 s. After 30 days of continuous testing, the response of 15 wt% CuO/WO3 decreased slightly but maintained the initial response of 90.5%. The improved performance is attributed to (1) the p-n heterojunction formed between CuO and WO3 optimizes the energy band structure and enriches the chemisorption sites for H2S; (2) the reaction of H2S with CuO generates highly conductive CuS, which significantly reduces the interfacial resistance; and (3) the hierarchical flowery hollow microsphere structure, heterojunction, and oxygen vacancy synergistically promote the desorption. This work provides a high-performance H2S gas sensor that balances response, selectivity, and response/recovery kinetics. Full article
(This article belongs to the Special Issue Recent Progress in Nano Material-Based Gas Sensors)
Show Figures

Graphical abstract

15 pages, 3671 KiB  
Article
Improving the Water–Gas Shift Performance of a Co/CeO2 Catalyst for Hydrogen Production
by Nipatta Chumanee and Pannipa Nachai
ChemEngineering 2025, 9(4), 71; https://doi.org/10.3390/chemengineering9040071 - 10 Jul 2025
Viewed by 330
Abstract
The aim of this study was to improve the water–gas shift efficiency of Co/CeO2 catalyst by incorporating praseodymium and rhenium. The catalysts were synthesized via combustion method and characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Scanning Electron Microscope (SEM), [...] Read more.
The aim of this study was to improve the water–gas shift efficiency of Co/CeO2 catalyst by incorporating praseodymium and rhenium. The catalysts were synthesized via combustion method and characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Scanning Electron Microscope (SEM), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3-TPD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). These characterization techniques evaluate the increase of the surface acidity and oxygen vacancies in Co-based catalysts, which leads to an increase in water–gas shift performance because CO molecules prefer to react with surface oxygen, then followed by the production of CO2 and oxygen vacancies which act as active sites for H2O dissociation. The 1%Re4%Co/Ce-5%Pr-O catalyst exhibited a maximum CO conversion of 86% at 450 °C, substantially outperforming the 5%Co/Ce-5%Pr-O catalyst, which showed only 62% CO conversion at 600 °C. In addition, 1%Re4%Co/Ce-5%Pr-O catalyst is more resistant towards deactivation than 5%Co/Ce-5%Pr-O. The result presented that the catalytic activity of 1%Re4%Co/Ce-5%Pr-O catalyst was kept constant for the whole period of 50 h, while a 6% decrease in water–gas shift activity was found for the 5%Co/Ce-5%Pr-O catalyst. Moreover, the addition of rhenium into the Co/Ce-Pr-O catalyst reveals that the enhancement of oxygen vacancy concentration, oxygen mobility, and surface acidity, thereby enhances CO conversion efficiency. Full article
Show Figures

Figure 1

22 pages, 4229 KiB  
Article
CO2 Methanation over Ni Catalysts Supported on Pr-Doped CeO2 Nanostructures Synthesized via Hydrothermal and Co-Precipitation Methods
by Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Aasif A. Dabbawala, Aseel G. S. Hussien, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Samuel Mao, Kyriaki Polychronopoulou and Maria A. Goula
Nanomaterials 2025, 15(13), 1022; https://doi.org/10.3390/nano15131022 - 1 Jul 2025
Viewed by 436
Abstract
The synthesis method of the Pr-doped CeO2 catalyst support in Ni/Pr-CeO2 CO2 methanation catalysts is varied by changing the type/basicity of the precipitating solution and the hydrothermal treatment temperature. The use of highly basic NaOH as the precipitating agent and [...] Read more.
The synthesis method of the Pr-doped CeO2 catalyst support in Ni/Pr-CeO2 CO2 methanation catalysts is varied by changing the type/basicity of the precipitating solution and the hydrothermal treatment temperature. The use of highly basic NaOH as the precipitating agent and elevated hydrothermal treatment temperature (100 or 180 °C) leads to the formation of structured Pr-doped CeO2 nanorods and nanocubes, respectively, whereas the use of a mildly basic NH3-based buffer in the absence of hydrothermal treatment (i.e., co-precipitation) leads to an unstructured mesoporous morphology with medium-sized supported Ni nanoparticles. The latter catalyst (Ni/CP_NH3) displays a high surface area, high population of moderately strong basic sites, high oxygen vacancy population, and favorable Ni dispersion. These properties lead to a higher catalytic activity for CO2 methanation (75% CO2 conversion and 99% CH4 selectivity at 350 °C) compared to the catalysts with structured nanorod and nanocube support morphologies, which are found to contain a significant amount of leftover Na from the synthesis procedure that can act as a catalyst inhibitor. In addition, the best-performing Ni/CP_NH3 catalyst is shown to be highly stable, with minimal deactivation during time-on-stream operation. Full article
Show Figures

Graphical abstract

Back to TopTop