ArchiveThe efficiency and stability of catalysts for photocatalytic hydrogen evolution (PHE) are largely governed by the charge transfer behaviors across the heterojunction interfaces. In this study, CuO, a typical semiconductor featuring a broad spectral absorption range, is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction. The optimized photocatalyst (CdS-CuO2∶1) delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h), 4.15-fold higher compared with bare CdS. X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflection absorption spectroscopy (UV-vis DRS) confirmed the S-scheme band structure of the composites. Moreover, the surface photovoltage (SPV) and electron paramagnetic resonance (EPR) indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band (CB) of CdS with a higher reduction potential and the valence band (VB) of CuO with a higher oxidation potential under illumination, as expected for the S-scheme mechanism. Density-functional-theory calculations of the electron density difference (EDD) disclose an interfacial electric field oriented from CdS to CuO. This built-in field suppresses charge recombination and accelerates carrier migration, rationalizing the markedly enhanced PHE activity. This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-to-hydrogen conversion.
In this study, a straightforward one-step hydrothermal method was successfully utilized to synthesize the solid solution Na0.9Mg0.45Ti3.55O8-Na2Ni2Ti6O16 (NNMTO-x), where x denotes the molar percentage of Na2Ni2Ti6O16 (NNTO) within Na0.9Mg0.45Ti3.55O8 (NMTO), with x values of 10, 20, 30, 40, and 50. Both XPS (X-ray Photoelectron Spectroscopy) and EDX (Energy Dispersive X-ray Spectroscopy) analyses unequivocally validated the formation of the NNMTO-x solid solutions. It was observed that when x is below 40, the NNMTO-x solid solution retains the structural characteristics of the original NMTO. However, beyond this threshold, significant alterations in crystal morphology were noted, accompanied by a noticeable decline in photocatalytic activity. Notably, the absorption edge of NNMTO-x (x<40) exhibited a shift towards the visible-light spectrum, thereby substantially broadening the absorption range. The findings highlight that NNMTO-30 possesses the most pronounced photocatalytic activity for the reduction of CO2. Specifically, after a 6 h irradiation period, the production rates of CO and CH4 were recorded at 42.38 and 1.47 μmol/g, respectively. This investigation provides pivotal insights that are instrumental in the advancement of highly efficient and stable photocatalysts tailored for CO2 reduction processes.
Needle coke, a high-performance artificial carbon material, requires precise composition control of its raw materials as this critically determines the structural characteristics and performance of the final product. In this study, needle coke samples were prepared from coal direct liquefaction pitch (CDLP) and waste engine oil (WEO) through component optimization and a co-carbonization process. The microstructure and properties were investigated using the following characterization techniques: Fourier Transform Infrared Spectroscopy (FT-IR), Polarized Light Microscopy (PLM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Micro-Strength (MS) and Powder Resistivity (PR). The co-carbonization mechanism of CDLP and WEO was systematically investigated. The results indicated that the incorporation of WEO significantly reduced the viscosity of the co-carbonization system, and its abundant aliphatic structures provided alkyl radicals and active sites. The synergistic interaction of aromatic components between the CDLP and WEO effectively promoted the growth and order accumulation of aromatic carbon layers. When 50% WEO was introduced, the prepared needle coke exhibited an excellent microstructure and properties. The fibrous and leaflet structure content reached 76.2%, the ideal graphite lattice content reached 89.7%. These results demonstrated remarkable oxidation resistance and electrical conductivity, with a powder resistivity of 605.1 mΩ·mm. This work establishes a process with cost advantages for the production of needle coke.
To elucidate the effect of calcite-regulated activated carbon (AC) structure on low-temperature denitrification performance of SCR catalysts, this work prepared a series of Mn-Ce/De-AC-xCaCO3 (x is the calcite content in coal) catalysts were prepared by the incipient wetness impregnation method, followed by acid washing to remove calcium-containing minerals. Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity. Specifically, NO conversion increased from 88.3% of Mn-Ce/De-AC to 91.7% of Mn-Ce/De-AC-1CaCO3 (210 °C). The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn4+ content and Ce4+/Ce3+ ratio, an abundance of chemisorbed oxygen and acidic sites, which could strengthen the SCR reaction pathways (richer NH3 activated species and bidentate nitrate active species). Therefore, NO removal is enhanced.
In this paper, the Ag@AgBr/MgAl-LDH complex was prepared by hydrothermal, precipitation and photoreduction methods, and the target product, methylene blue (MB) solution, was catalytically degraded under the condition of photoelectric synergy, and the catalytic activity of the samples was studied by the degradation rate. By combining with Ag@AgBr, Ag@AgBr/MgAl-LDH composite photocatalytic materials can be prepared. Ag@AgBr has the surface plasmon resonance (SPR) effect, and a certain voltage is applied to it by an electrochemical workstation, which can promote the efficient separation of photogenerated electrons from holes and greatly reduce the recombination of the two, and greatly improve the activity of catalytic degradation. This study provides an effective solution to the environmental problems caused by pollution such as industrial wastewater and organic dyes, and has important research value and application prospects. During the experiment, the photocatalytic performance of the sample was studied by the difference in the degradation rate of the sample to the methylene blue solution. Through a series of chemical characterization and photoelectric activity tests such as XRD and SEM of the prepared materials, the material composition, microscopic morphology and particle size and other parameters of the samples were determined. Parameters such as the electrochemical properties of materials are characterized by the use of potentiostats; The optimal modification amount of the catalyst was determined by exploring the degradation rate of the composite under different Ag@AgBr modification amounts of the sample. The recovery performance of the catalyst was characterized by multiple test cycle experiments on the samples. The reaction mechanism of the catalyst was determined by quenching experiments; The reaction mechanism of the active substance was determined by quenching the experiment. Through experiments, it is proved that when the Ag@AgBr modification amount is 12.5%, the photoelectric synergistic degradation rate of Ag@AgBr/MgAl-LDH is the highest, and the degradation rate can reach 90.97%. Through XRD, SEM, ultraviolet-visible diffuse reflection and Fourier transform infrared (FT-IR) characterization of the material, it was proved that the Ag@AgBr was successfully modified to MgAl-LDH, and the material also had good hydrophilic properties. A series of electrochemical performance tests were carried out on Ag@AgBr/MgAl-LDH by electrochemical workstation to characterize the electrochemical properties of the materials, and the results showed that the composite electrode materials had low barrier widths and impedances, high catalytic degradation ability, and more catalytic reaction active sites. After 5 cycle experiments, the material still has a high degradation rate, so it can be found that the composite material has very good stability, less catalyst loss and no significant degradation rate. The experimental results show that the active species in the process of photoelectric synergistic degradation of Ag@AgBr/MgAl-LDH are quenched by using different quenchers, and the experimental results show that the active species in the process are h+ and
KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method, and NiW/KIT-5/Beta catalysts were prepared by impregnation. A series of characterization techniques were utilized to evaluate the influence of varying hydrothermal synthesis temperatures on the physicochemical properties of both the KIT-5/Beta supports and the resulting catalysts. The catalytic performances of catalysts were evaluated under reaction conditions of 320 °C, 4 MPa H2 pressure, and a weight hourly space velocity (WHSV) of 4.8 h−1 for hydrodenitrogenation (HDN) of quinoline. The results indicated that the specific surface area and pore structure of the materials could be effectively regulated by adjusting the hydrothermal synthesis temperature, which in turn influenced the number of active sites on the catalyst. The NiW/KB-125 catalyst, synthesized at 125 °C, presented the highest quinoline HDN efficiency (96.8%), which can be attributed to its favorable pore channel structure, greater Brønsted acid number, higher degree of metal sulfidation (80.12%) and appropriate metal-support interaction (MSI).
Coal-fired power plants, as the primary source of CO2 emissions, have garnered significant attention for carbon reduction under the “dual carbon” goals. CO2 methanation is considered to be the most practical and effective way to achieve carbon recycling, however, the most widely used nickel-based catalysts in CO2 methanation are prone to sulfur poisoning deactivation due to SO2 in the flue gas. In this paper, a series of Mn-modified Ni/γ-Al2O3 were prepared by wet impregnation method, which had anti-sulfur poisoning properties. The structure and physicochemical properties of the catalysts were investigated using various methods such as XRD, XPS, CO2-TPD, SO2-TPD and H2-TPR, and the mechanism by which the maintain high catalytic activity while possessing sulfur resistance was elucidated. The results show that 4Mn-Ni/Al2O3 exhibits the best catalytic performance and sulfur resistance, with a maximum CO2 conversion rate of 88.27%. After 3 h of SO2 exposure, the CO2 conversion rate only decreased by 11.32%. Mechanistic studies indicate that Mn can serve as a sacrificial site to protect Ni sites from sulfur poisoning, while the interaction between Ni and Mn suppresses the adsorption of SO2 on the catalyst surface, thereby enhancing sulfur resistance. This research provides a feasible solution for the direct methanation of CO2 from coal-fired SO2 flue gas.
Considering that coal quality is a key factor affecting the performance of coal water slurry (CWS), in this research, the composition and structure of five coal samples from the Xinjiang-Zhundong coal B2, B3, B5, Heishan coal (HS), Hongshaquan coal (HSQ) and Naomaohu coke (XTJ)-were analyzed, aiming to investigate the influence mechanisms of single coals and coal/coke blending on slurryability. The results showed that the HS, characterized by the aromatic carbon skeleton dominated by 2−3 rings, exhibited low oxygen content and few hydrophilic phenolic hydroxyl, carbonyl, and carboxyl groups, which contributed to its superior slurry performance compared to other coal samples. Even at a remarkably high slurry concentration of 70.98%, the apparent viscosity remained as low as 858 mPa·s. In contrast, B3 and B5 exhibited poor slurry performance due to their abundant oxygen-containing functional groups and strong hydrophilicity, which reduced free water content in the slurry. Additionally, the high content of adsorbed water indicated a thicker hydration film on coal particle surfaces, hindering dispersant adsorption. The addition of 20% HS/XTJ to B5 disrupted the three-dimensional network structure formed by clustered particles and covered the oxygen-containing functional groups. This process not only released previously encapsulated water but also reduced hydration layer thickness. Consequently, free water content increased within the slurry, enhancing dispersant performance. These effects collectively increased coal slurry concentration by approximately 2.40% (reaching 59.00%), reduced apparent viscosity by ~40%, and improved fluidity to an A+ rating.
Hydrogen peroxide (H2O2) oxidation and reduction reactions (HPOR/HPRR) are pivotal in various innovative electrochemical energy conversion devices. A comprehensive understanding of these mechanisms is critical for catalyst design and performance improvement in these applications. In this work, we systematically investigate the HPOR/HPRR mechanisms on low-index Pt surfaces, specifically Pt(111), Pt(100) and Pt(110), through density functional theory (DFT) calculations combined with the computational hydrogen electrode (CHE) model. For HPOR, all the low-index Pt surfaces exhibit a unified potential-determining step (PDS) involving the electrochemical oxidation of hydroperoxyl intermediates (HOO*). The binding free energy of HOO* (ΔGHOO*) emerges as an activity descriptor, with Pt(110) exhibiting the highest HPOR activity. The HPRR mechanism follows a chem-electrochemical (C-EC) pathway. The rate-determining step (RDS) of HPRR is either the cleavage of the HO–OH bond (chemical) or the reduction of HO (electrochemical), depending on their respective activation energies. These activation energies are functions of the HO* binding free energy, ΔGHO*, establishing ΔGHO* as the descriptor for HPRR activity prediction. Pt(111) and Pt(100) are identified as the most active HPRR catalysts among the studied metal surfaces, although they still experience a significant overpotential. The scaling relationship between ΔGHOO* and ΔGHO* reveals a thermodynamic coupling of HPOR and HPRR, explaining their occurrence on Pt surfaces. These findings provide important insights and activity descriptors for both HPOR and HPRR, providing valuable guidance for the design of electrocatalysts in H2O2-related energy applications and fuel cells.
Against the backdrop of escalating global climate change and energy crises, the resource utilization of carbon dioxide (CO2), a major greenhouse gas, has become a crucial pathway for achieving carbon peaking and carbon neutrality goals. The hydrogenation of CO2 to methanol not only enables carbon sequestration and recycling, but also provides a route to produce high value-added fuels and basic chemical feedstocks, holding significant environmental and economic potential. However, this conversion process is thermodynamically and kinetically limited, and traditional catalyst systems (e.g., Cu/ZnO/Al2O3) exhibit inadequate activity, selectivity, and stability under mild conditions. Therefore, the development of novel high-performance catalysts with precisely tunable structures and functionalities is imperative. Metal-organic frameworks (MOFs), as crystalline porous materials with high surface area, tunable pore structures, and diverse metal-ligand compositions, have the great potential in CO2 hydrogenation catalysis. Their structural design flexibility allows for the construction of well-dispersed active sites, tailored electronic environments, and enhanced metal-support interactions. This review systematically summarizes the recent advances in MOF-based and MOF-derived catalysts for CO2 hydrogenation to methanol, focusing on four design strategies: (1) spatial confinement and in situ construction, (2) defect engineering and ion-exchange, (3) bimetallic synergy and hybrid structure design, and (4) MOF-derived nanomaterial synthesis. These approaches significantly improve CO2 conversion and methanol selectivity by optimizing metal dispersion, interfacial structures, and reaction pathways. The reaction mechanism is further explored by focusing on the three main reaction pathways: the formate pathway (HCOO*), the RWGS (Reverse Water Gas Shift reaction) + CO* hydrogenation pathway, and the trans-COOH pathway. In situ spectroscopic studies and density functional theory (DFT) calculations elucidate the formation and transformation of key intermediates, as well as the roles of active sites, metal-support interfaces, oxygen vacancies, and promoters. Additionally, representative catalytic performance data for MOF-based systems are compiled and compared, demonstrating their advantages over traditional catalysts in terms of CO2 conversion, methanol selectivity, and space-time yield. Future perspectives for MOF-based CO2 hydrogenation catalysts will prioritize two main directions: structural design and mechanistic understanding. The precise construction of active sites through multi-metallic synergy, defect engineering, and interfacial electronic modulation should be made to enhance catalyst selectivity and stability. In addition, advanced in situ characterization techniques combined with theoretical modeling are essential to unravel the detailed reaction mechanisms and intermediate behaviors, thereby guiding rational catalyst design. Moreover, to enable industrial application, challenges related to thermal/hydrothermal stability, catalyst recyclability, and cost-effective large-scale synthesis must be addressed. The development of green, scalable preparation methods and the integration of MOF catalysts into practical reaction systems (e.g., flow reactors) will be crucial for bridging the gap between laboratory research and commercial deployment. Ultimately, multi-scale structure-performance optimization and catalytic system integration will be vital for accelerating the industrialization of MOF-based CO2-to-methanol technologies.
The development of materials with excellent microwave absorption (MWA) and electromagnetic interference (EMI) shielding performances has currently received attention. Herein, mesophase pitch-based carbon foam (MPCF) with 3D interconnected pore structure was prepared through the high pressure pyrolysis of mesophase coal tar pitch. It is found that the 3D interconnected cellular pores of MPCF facilitate multiple reflections of electromagnetic waves, which results in the minimum reflection loss (RLmin) value of MPCF reaches −37.84 dB with the effective absorption bandwidth (EAB) of 5.44 GHz at a thickness of 2.70 mm, and the total average electromagnetic shielding effectiveness (SET) under 3.00 mm thickness achieves 26.52 dB in X-band. Subsequently, MPCF is activated by KOH to obtain activated carbon foam (A-MPCF). The average SET of A-MPCF achieves 103.00 dB for abundant nanopores on the pore cell walls, which leads to a transition from the multiple reflections of electromagnetic waves on the walls to diffuse reflection. Unfortunately, the reflection coefficient (R) of A-MPCF increases from 0.78 to 0.90. To reduce the R value, Fe3O4/A-MPCF was fabricated via the in situ growth of nano Fe3O4 on A-MPCF. Consequently, the R value of Fe3O4/A-MPCF was reduced from 0.90 to 0.74, whereas the MWA performance was only slightly decreased. This work proposes a simple strategy for simultaneously adjusting MWA and EMI shielding performances of materials.
Energetic materials play a crucial role in military and aerospace applications. However, the discovery and synthesis of novel energetic compounds still largely rely on traditional trial-and-error approaches, which severely hinder the development of novel energetic materials. This study focuses on the prediction of a key thermodynamic property of energetic materials—heat of formation (HOF) and proposes a machine learning structure-property relationship model that integrates active learning strategies with SMILES-based molecular feature representation. A dataset containing 1447 gas-phase energetic molecules was constructed based on the high-accuracy G4 quantum chemical method, and 93 effective SMILES descriptors were extracted to establish a preliminary model for gas-phase HOF using linear model. Subsequently, the model was applied on the systematical prediction of 221738 potential energetic molecules retrieved from the PubChem database, enabling the screening of candidates with superior explosive performance. For samples with high prediction errors, an active learning strategy was implemented to iteratively refine the model parameters, significantly improving prediction accuracy. Validation on classical energetic molecules illustrated excellent predictive performance, highlighting the model’s strong generalization capability. Finally, 20 candidate molecules with a TNT equivalent power index exceeding 2.0 were screened, most of which are new to the existing reservoir of known energetic materials. These results underscore the potential of this proposed approach in accelerating the discovery of high-performance energetic materials and offer a new strategy for the development of next-generation energetic compounds.
To achieve the resource utilization of red mud, this work prepares FexOy/BaTiO3/C composite microwave absorbing materials using red mud as the iron source and soluble starch as the carbon source, employing sol-gel and solid-state reaction methods. First, a BaTiO3 precursor sol is obtained through the sol-gel process using titanium butoxide and barium acetate, which is then mixed uniformly with red mud and soluble starch. During the solid-state reaction, Fe2O3 in the red mud undergoes in situ carbothermic reduction to form Fe3O4 and Fe, which are evenly distributed within the composite, and the BaTiO3 exhibits a needle-like morphology. Experimental results show that by adjusting the solid-state reaction temperature and the raw material ratio, the phase composition, microstructure, and microwave absorption performance of the composites can be optimized. When the temperature is 700 ℃, RmBTS-700-1.2 exhibits a minimum reflection loss of −16.0 dB at a coating thickness of 2.0 mm, with an effective absorption bandwidth of 3.0 GHz. Meanwhile, RmBTS-700-1.8 achieves a minimum reflection loss of −32.6 dB at 10.7 GHz under the same coating thickness. The FexOy/BaTiO3/C composite microwave absorbing materials prepared in this study exhibit both strong dielectric loss and magnetic loss capabilities, providing a new approach for the comprehensive utilization of red mud and contributing to the realization of the carbon neutrality and carbon peak goals.
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