High-entropy alloy nanoparticles (HEA NPs), with unique multi-element synergistic effects and excellent structural stability, are promising core materials for high-efficiency electrocatalysts, but precise regulation of their morphology and composition remains a critical challenge. In this study, cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC) were used as structure-directing agents to controllably synthesize PtPdRuRhCuMo HEA NPs via solvothermal method, and their regulatory effects on material properties were systematically investigated. Structural characterizations showed HEA-1 (CTAB-prepared) had superior dispersibility, uniform particle size and high crystallinity, while HEA-2 (CTAC-prepared) exhibited agglomeration and uneven particle size. Electrochemical tests revealed HEA-1 achieved a mass activity of 2.4 A/mg in alkaline EGOR, significantly higher than HEA-2 and commercial Pt/C (1.25 A/mg) and retained 50% initial activity after 10 h continuous testing, showing certain stability. Structure-directing agents determine HEA NPs’ structural characteristics and thus their electrocatalytic performance; HEA-1’s excellence is attributed to CTAB-mediated regular structure and strong multi-metal electronic interactions. This work provides a new strategy for precise regulation of HEA NPs and lays a foundation for their practical application in energy conversion systems.
In this study, ZSM-22-ZSM-23 composite zeolite was synthesized via a mechanical mixing method. The morphology, acidic properties, and textural properties of the samples were characterized by XRD, SEM, TEM, NH3-TPD, Py-FTIR, and N2 adsorption-desorption techniques. The hydroisomerization catalytic performance of the composite zeolite was evaluated using n-dodecane as a model reactant, and compared against the individual zeolite components. It was found that the textural and acidic properties could be precisely modulated by varying the ZSM-22 to ZSM-23 mass ratio. At an optimal mass ratio of 4:1, the selectivity for iso-dodecane increased by 24% relative to ZSM-23, while the ratio of terminal-branching to intermediate-branching product selectivity (st/si) decreased by 14% compared to ZSM-22. The results demonstrate that the composite zeolite combines the advantages of both individual zeolite in terms of texture and acidity, exhibits superior hydroisomerization performance, and can effectively regulate the distribution of terminal-branching and intermediate-branching isomers in iso-dodecane.
In this study, corn straw was used as the raw material and subjected to low-temperature pyrolysis in a tubular furnace within the range of 400–500 °C to investigate the effects of pyrolysis temperature on the physicochemical properties of biochar and the migration behavior of alkali metal potassium (K). Elemental analysis, FT-IR, SEM and BET techniques were employed to examine the effects of temperature on the properties of biochar. The results showed that with increasing pyrolysis temperature, the fixed carbon content increased, while the volatile matter and oxygen-containing functional groups decreased. The pore structure gradually developed, with the specific surface area and pore volume reaching their maximum values at 475 °C. The total K content decreased with increasing temperature, and its occurrence transformed from water-soluble to organic-bound and residue-bound forms. When the biochar was blended with coal to prepare biochar-coal-water slurry, it was found that within 400–475 °C, potassium ions reacted with carboxyl groups to form potassium carboxylates, reducing hydrophilic groups and enhancing particle hydrophobicity, consequently, the fluidity of the multicomponent slurry is improved and its viscosity is reduced. At 500 °C, mineral deposition led to pore blockage and increased its viscosity. Furthermore, surface modification of biochar particles with kerosene significantly improved the performance of the multicomponent slurry, increasing the maximum slurry concentration by about 2.6%. The study elucidates the structure-activity mechanisms governing the performance of co-slurrying corn-stalk pyrolysis char with coal, providing a theoretical basis for the efficient utilization of biochar in coal-water slurry systems and broader energy applications.
Low-temperature CO oxidation technology has been widely applied in the field of environmental pollution control, yet challenges remain in CO purification under high-moisture environments. In this study, a series of CuCeOx-Sn catalysts supported on CeO2 were prepared via the excess impregnation method, and their catalytic performance in the low-temperature catalytic combustion of CO was systematically evaluated. The results indicate that CuCeOx-Sn0.1 (with a Sn loading of 0.1%) exhibits the optimal low-temperature catalytic activity, with the lowest t50 and t90 values. The temperature for 90% CO conversion (t50 and t90) decreases progressively with increasing Sn loading up to 0.1%. Beyond this threshold, further Sn loading does not lead to a significant reduction in t90; in fact, t90 slightly increases compared to that observed at 0.1% Sn. Furthermore, this catalyst maintains stability during water-on/water-off switching tests, demonstrating excellent water resistance. Through characterization techniques including XPS, O2-TPD, CO-TPD and CO-TPSR, it is revealed that the introduction of Sn effectively increases the concentration of surface oxygen vacancies and promotes the activation and migration of surface adsorbed oxygen and lattice oxygen.
The rapid expansion of the biodiesel industry plays a crucial role in achieving carbon neutrality and promoting energy system transformation. However, the oversupply of the by-product glycerol has hindered the sustainable development of biodiesel industry. Therefore, the green conversion of the by-product glycerol is conducive to the sustainable development of the biodiesel industry. Among various valorization routes, the hydrogenolysis of glycerol to C3 oxygenated chemicals is considered one of the most promising pathways. This review first briefly introduces glycerol chemistry and the fundamental reaction mechanism of glycerol hydrogenolysis. Subsequently, recent advances in catalytic systems for the selective hydrogenolysis of glycerol to high-value C3 oxygenated chemicals such as 1,2-propanediol, 1,3-propanediol, 1-propanol and propanal, are comprehensively summarized. Finally, future research directions and development trends in glycerol hydrogenolysis are discussed.
The HZSM-5 zeolite was co-modified with levulinic acid (LA) and Zn to obtain L/Zn0.2-ZSM5. Comprehensive characterization was conducted using XRD, N2 adsorption-desorption, NH3-TPD, Py-FTIR, Raman, XPS and TGA to investigate the effects of co-modification on the catalyst’s structure, physicochemical properties, catalytic performance, and coke-deposition behavior. The results indicate that L/Zn0.2-ZSM5 possesses a specific surface area comparable to that of HZSM-5, while exhibiting significantly larger pore volume and average pore size than HZSM-5 and the singly modified catalysts (L-ZSM5 and Zn0.2-ZSM5). In addition, co-modification markedly decreases the total acid amount and acid strength, while establishing a moderate Brønsted-to-Lewis (B/L) acid ratio. These structural and acidic modifications endow L/Zn0.2-ZSM5 with a BTX (benzene, toluene, xylene) selectivity of 58.75% and a catalytic lifetime of 128 h, both of which surpass those of the singly modified catalysts and those with different Zn loadings. The enhanced catalytic performance of L/Zn0.2-ZSM5 correlates with its significantly lower proportion of internal coke and greater coke storage capacity compared with the unmodified and singly modified catalysts. This behavior is attributed to the co-modification-induced pore enlargement, which effectively reduces the diffusion resistance of coke precursors and suppresses the graphitization process of coke. Furthermore, LA strengthens the interaction between Zn species and the zeolite framework, promotes Zn dispersion, and substantially increases the proportion of [ZnOH]+ species to 61.36%.
Organic phase change materials (PCMs), known for their excellent energy storage properties, have been widely applied in thermal management and energy storage fields. This review summarizes the main types and performance optimization strategies of organic PCMs. In terms of thermophysical property regulation, methods such as constructing eutectic systems, modifying molecular structures and incorporating nanoparticles to adjust phase change temperature and latent heat are introduced. For thermal conductivity enhancement, strategies involving composites with zero-, one-, two- and three-dimensional high thermal conductivity materials are reviewed. Additionally, countermeasures for common issues like supercooling and flammability of organic PCMs are analyzed, including methods to suppress supercooling and flame-retardant modification techniques. Finally, future development directions of organic PCMs are discussed, highlighting their broader application prospects in energy storage and thermal management as technology advances.
Accurate prediction of the thermophysical properties of biodiesel-alcohol blends is essential for spray combustion simulation when used as alternative marine fuels. To address the limitations of existing prediction models in terms of generalization capability and interpretability, this study systematically evaluated the predictive performance and applicability of Ridge regression, Artificial Neural Network (ANN), Random Forest and XGBoost models for estimating the density and viscosity of the blends. The results indicated that the XGBoost model outperforms the other three models, achieving mean absolute percentage errors (MAPE) of 0.05% for density and 1.89% for viscosity on unseen test data. Statistical tests confirmed the significantly superior performance of this model. Furthermore, interpretability analysis based on SHapley Additive exPlanations (SHAP) disclosed that, in the XGBoost model, initial density (ρ20) and experimental temperature (T) are the key inputs for density prediction, while T and initial viscosity (η20) are the most influential for viscosity prediction. Finally, robustness testing demonstrated that the XGBoost model maintains excellent stability and generalization capability with input noise levels up to 2%, thereby providing high-precision data support for numerical simulation of in-cylinder spray characteristics in internal combustion engines.
Carbon-based oxygen reduction reaction (ORR) catalysts have attracted widespread attention due to their low cost, high conductivity, tunable structures, and excellent stability. In this work, wastepaper was used as a carbon source, while urea and dicyandiamide served as nitrogen sources, to successfully prepare two types of nitrogen-doped carbon nanotubes (N-CNTs) through a one-step pyrolysis method. The physicochemical properties and ORR catalytic performance of the materials were systematically investigated using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and electrochemical measurements. Structural characterization revealed that the urea-derived carbon nanotubes (UCNTs-0.15) possessed a unique wrinkled tubular morphology and exhibited a high pyridinic-N content of up to 20%, significantly higher than the 11% observed in the dicyandiamide-derived sample (DCNTs-0.15). Electrochemical tests demonstrated that UCNTs-0.15 displayed excellent ORR activity in 0.1 mol/L KOH, with an onset potential of 0.94 V and a half-wave potential of 0.74 V (vs. RHE), an electron-transfer number close to 4, and markedly superior stability compared to DCNTs-0.15. Zinc-air batteries assembled with UCNTs-0.15 achieved a peak power density of 80 mW/cm2 and a specific capacity of 644 mA·h/g (based on Zn), and maintained stable cycling for 60 h. Mechanistic studies indicated that urea releases NH3 at low temperatures during pyrolysis, promoting the formation of Fe3N and pyridinic/graphitic N doping, whereas dicyandiamide releases HCN at higher temperatures, leading instead to Fe3C formation and predominantly pyrrolic-N structures. This work elucidates how the choice of nitrogen source regulates the phase of Fe catalysts and nitrogen-release behavior, thereby determining the structure and performance of carbon nanotubes. The findings provide theoretical and experimental insights for the high-value utilization of wastepaper and the sustainable design of electrocatalysts.
Chemical looping, with its advantages of efficient product separation and low energy consumption, has emerged as a crucial technical pathway for the CO2 conversion and hydrogen production via water splitting. Oxygen carriers, functioning within the chemical looping cycle, undertaking oxygen storage and transfer and participating in the redox reactions, serve as a key component that determines the reaction rates and product selectivity. To screen high-performance oxygen carriers, this study employed the Gibbs free energy analysis method to thermodynamically investigate the chemical looping reactions involving typical metals and corresponding oxides for the CO2 conversion and hydrogen production via water splitting. Based on the Ellingham diagrams, the feasibility of the conversion reactions and the performance of various metal-based oxygen carriers were evaluated. The Gibbs free energies for the oxidation of metals (such as iron, vanadium, manganese, cobalt, copper and cerium) and that for the reactions between these metals and water were obtained. The feasibility and critical temperatures of the reactions of various metals and their oxides with CO2 and water across different temperature ranges were clarified, which revealed the superior capability of the Fe/Mn-based oxygen carriers for CO2 reduction at high temperatures and the great hydrogen production potential of Mn/Cu/Ce-based oxygen carriers at low temperatures. The results indicate that high temperatures can promote the reduction of CO2 by iron, manganese, and their reduced oxides, with initial reaction temperatures of 708 °C for Fe and 935°C for Mn; in addition, the promoting effect becomes more pronounced at higher temperatures. Thermodynamically, manganese, copper, and cerium can spontaneously decompose water to produce hydrogen at relatively low temperatures. This study delineates the relative redox performance of various metals with CO2 and H2O at different temperatures, providing a thermodynamic theoretical basis for the screening and optimization of oxygen carriers in the chemical looping reactions.