JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Zijie Zhang,Qiao Yin,Linlin Xu,Jiaming Zhai,Chun Guo,Yongqiang Niu,Liwei Zhang,Mingliang Li,Hailong Wang,Li Guan,Rui Zhang,Hongxia Lu
The construction of new semiconductor photocatalysts toward the enhancement of photocatalytic activity under visible-light is crucial for a sustainable and clean future. In this paper, cation doping and heterojunction construction were synergistically used to synthesize g-C 3 N 4 matrix composite with a narrow band gap and low recombination rate of photogenerated electron-hole pairs. Potassium-doped-C 3 N 4 (KCN) was used as the matrix to construct semiconductor heterojunction with Cd 0.5 Zn 0.5 S (CZS) by hydrothermal method . The resulting composites were characterized through X-ray diffraction, infrared radiation, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy techniques to examine its phase structure, morphological, valance state and optical properties respectively. The photocatalytic performance of the samples evaluated by H 2 evolution and degrading the Rhodamine B (RhB) aqueous solution. After 12 h hydrothermal reaction at 140 °C, CZS particles uniformly distributed on the KCN matrix. The photocatalytic hydrogen production rate (HPR) of the sample loaded 24 wt% CZS (KCN/CZS 24 wt%) reaches 1.83 mmol/g·h which is 5.6 times of pristine g-C 3 N 4 . The degradation rate constant on RhB of KCN/CZS 24 wt% is ( k = 0.041 min −1 ) 7.9 times higher than g-C 3 N 4 . The enhanced photocatalytic activity can be attributed to the well-matched energy level of KCN and CZS as well as the extended light absorption of the composites.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2013
·Vol. 7
·期 3
·297-302
·
IF 0
Xiao Qiang,Tang Xiaodan,Liu Yefeng,Zhong Yijun,Zhu Weidong
A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li 2 ZrO 3 and Kdoped Li 2 ZrO 3 absorbents for CO 2 capture at high temperatures, including solid-state and liquid-phase methods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermogravimetric analysis (TGA) at different CO 2 partial pressures. The nanosized Li 2 ZrO 3 crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li 2 ZrO 3 can significantly improve the uptake rate of CO 2 , especially at low CO 2 partial pressures. For the synthesis of K-doped Li 2 ZrO 3 , the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO 2 capture properties.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Nan Xin,Yifei Li,Guihua Tang,Longyun Shen
High-efficient and environment-friendly thermoelectric materials have attracted much attention. The single crystal tin selenide (SnSe) has a record high thermoelectric figure of merit ( ZT ) of 2.6 at ~800 K. Polycrystalline SnSe has better mechanical-strength but inferior ZT values than the single crystal, attribute to the paradoxically higher thermal conductivity ( κ ). In this work, we synthesized K x Sn 1−x Se (x = 0, 0.01, 0.02, 0.03 and 0.04) by doping K 2 CO 3 . A large number of point defects and dislocations generated with CO 2 volatilization, which possibly reduces κ . Based on this process, the K x Sn 1−x Se powders were followed by the hydrogen reduction with 4% H 2 − 96% Ar atmosphere to reduce tin oxide and potassium oxide which have high κ . These strategies lead to an ultra-low κ 0.32 Wm −1 K −1 in K 0.03 Sn 0.97 Se at 798 K. The effects of K doping on electronic transport performance of SnSe were studied by density functional theory calculation and experimental measurement. Doing K can narrow the band gap, increase hole concentration and enhance the electrical conductivity ( σ ) of SnSe. At 298 K, the σ of K x Sn 1−x Se increased by more than 2.5 times compared with the pristine SnSe. In high temperature region (623 K< T < 823 K), the σ is mainly affected by thermal excitation. High doping level of K (x = 0.03 and 0.04) suppresses the thermal excitation and limits the maximum of ZT . As the result, A high ZT of 1.06 is obtained at 798 K from K 0.01 Sn 0.99 Se perpendicular to the pressing direction, which is 103.8% larger than that of pristine SnSe. In addition, the hot-pressing polycrystalline K x Sn 1−x Se remains obvious lamellar morphology and show anisotropy. The σ and κ of K x Sn 1−x Se samples perpendicular to the pressure direction are much higher than those of the samples parallel to the pressure direction. This anisotropy decreases with the increasing K content.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2025
·
IF 10
Jian Gao,Yu Zhou,Bingran Wang,Wenxuan Luo,Peng Wu,Kai Shen,Yaping Zhang
Catalytic hydrolysis technology is a promising solution for carbonyl sulfide (COS) treatment, but it is still difficult to scale up due to the poor selectivity of H 2 S and low stability of the catalyst. Developing an efficient catalyst, therefore, remains a significant challenge. Although perovskite-based catalysts are widely utilized in various applications, they are less commonly applied to carbonyl sulfide hydrolysis. Moreover, the effects of doping modification and the hydrolysis reaction mechanism remain to be fully elucidated. Through extensive testing and evaluation of various lanthanide perovskite materials, LaAlO 3 has demonstrated excellent catalytic hydrolysis performance. At 100 °C, LaAlO 3 exhibits a COS removal efficiency of 37 % and an H 2 S selectivity of 52 %. After modification via potassium doping at the A-site, the catalyst achieves near-complete conversion of COS to H 2 S and maintains stable operation for extended periods under high space velocity. The adsorption energies of various adsorption sites were calculated using DFT, confirming the optimal adsorption sites for reactants COS and H 2 O. Water undergoes dissociative adsorption on the catalyst to form -OH groups, which then adsorb COS through the Eley-Rideal (E-R) mechanism, leading to the formation of the hydrolysis intermediate HSCO 2 − . Reactive oxygen species, on the other hand, facilitate the dissociative adsorption of H 2 O, leading to the formation of more surface hydroxyl groups. Meanwhile, calculations indicate that K doping significantly enhances the adsorption energy of the reactants. The structure and properties of the catalysts have been characterized using a variety of techniques. The results have shown that K doping increases the content of weak basic sites and O 2 − in LaAlO 3 . Consequently, the catalytic activity of La 0.8 K 0.2 AlO 3 prepared by the sol-gel method is enhanced, showing higher selectivity and stability. This work provides new solutions and insights for the application of perovskites in the field of environmental catalysis. Owing to its simple preparation method, low cost, and high efficiency, the modified LaAlO 3 catalyst exhibits excellent environmental and economic benefits.
研究领域:
环境催化
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Zhuojia Xie,Zhengguang Zou,Xinyu Jiang,Weijian Zhang
The effects of K + doping on structure, magnetic characteristics , magnetocaloric properties, and critical behavior of La 0.7-x Nd 0.1 Sr 0.2 K x Mn 0.95 Ni 0.05 O 3 (LNSKMNO) ceramics (x = 0.00, 0.05, and 0.10) were investigated. The X-ray diffraction and refinement findings revealed that LNSKMNO exhibited a distinctive rhombohedral structure of the R-3c space group (No. 167). To validate the chemical composition of LNSKMNO ceramics, EDS spectroscopy and X-ray photoelectron spectroscopy (XPS) were utilized. The magnetization of LNSKMNO exhibited a temperature-dependent behavior, revealing a phase transition from the ferromagnetic (FM) phase to the paramagnetic (PM) phase at approximately the Curie temperature (Tc). By utilizing normalization and Banerjee's criterion, the magnetic phase transition of LNSKMNO was determined to be a second order magnetic phase transition. The maximal magnetic entropy ( − Δ S M max ) of LNSKMNO around Tc was 4.24, 4.53, and 4.07 J/(kg K) at the 5 T external magnetic field (H). The Kouvel-Fisher approach and modified Arrott plot were used for determining the values of the critical exponents of β , γ , and δ . The critical exponents for LNSKMNO ceramics generally conformed to those obtained based on the Mean-field model.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Xi Chen,Xiaoyan Wang,Ziliang Jia,Chao Yang,Zhihong Liu,Yuexing Wei,Mengxue Wang,Meisheng Liang
K-doped Mn–Ce solid solution catalysts were synthesized using a combination of coprecipitation and hydrothermal methods, demonstrating excellent performance in benzene oxidation. The catalyst K 1 Ce 5 Mn 5 exhibited comparable activity to noble metal catalysts, achieving a 90 % benzene conversion at approximately 194 ℃. Durable tests under dry and moist conditions revealed that the catalyst could maintain its activity for 50 h at 218 ℃ and 236 ℃, respectively. Characterization results indicated that the catalyst’s enhanced activity resulted from the weakened Mn–O bonding caused by the introduction of K + , facilitating the activation of oxygen and its involvement in the reaction. CeO x , the main crystalline phase of Mn–Ce solid solutions, provided abundant oxygen vacancies for capturing and activating oxygen molecules for the weakened Mn–O structures. This conclusion was further supported by partial density of state analysis from density functional theory computations, revealing that the introduction of K + weakened the orbital hybridization of Mn3d and O2p. Finally, in situ diffuse reflectance infrared Fourier-transform spectroscopy ( in situ DRIFTS) studies on Ce 5 Mn 5 and K 1 Ce 5 Mn 5 catalysts suggested that the introduction of K + promoted the conversion of adsorbed benzene. Furthermore, intermediate products were transformed more rapidly for K 1 Ce 5 Mn 5 compared to Ce 5 Mn 5 .
研究领域:
催化化学
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Man Wang,Lichun Cheng,Lei Huang,Fengxin Ye,Qingrong Yao,Zhao Lu,Huaiying Zhou,Haiying Qi
Yttrium perovskite ferrite has a stable and symmetrical crystal structure and a simple preparation route. However, it exhibits poor absorption performance at 17–18 GHz. Several studies in the past have reported on the formation of mixed-valence states induced by the addition of monovalent K ions . In this study, YFeO 3 was synthesized by doping with monovalent K via the sol-gel auto combustion method. This greatly optimized the wave-absorbing properties and effective bandwidth of YFeO 3 . The influence of different K additions on the absorption properties of the materials was also studied. All the hybrid composites showed excellent absorbing properties, with Y 0.8 K 0.2 FeO 3 having an effective bandwidth of 4.88 GHz at a simulated thickness of 2.0 mm, Furthermore, the reflection loss (RL) value of Y 0.7 K 0.3 FeO 3 reached − 30.56 dB at 15.44 GHz (effective bandwidth up to 4.72 GHz) corresponding to the thickness of only 1.6 mm. This demonstrates that this broadband effect is greater than other similar materials. Moreover, the as-prepared samples completely covered the X and Ku band at only 2.2 mm, and the maximum effective bandwidth reached 5.28 GHz at 2.0 mm. The excellent wave absorption and frequency broadening effects were due to the various loss mechanisms and improved impedance matching characteristics caused by doping.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Greenhouse Gases-Science and Technology
·
2023
·Vol. 13
·期 5
·689-698
·
IF 2.2
Xuewei Tu,Luping Zhang,Yutong Chen,Shouxin Zhu,Can Sun,Jiali Jin,Min Liu,Hui Zheng
The conversion of CO 2 into valuable chemicals to reduce greenhouse gas emissions has received extensive attention. Converting CO 2 into pharmaceutical intermediates via graphitic carbon nitride (CN) at atmospheric pressure is a challenge. In this work, a series of novel graphitic carbon nitrides (K-CN) catalysts with different doping ratios of K were synthesized by post-treatment of CN with KOH as a dopant under magnetic stirring. Herein, substrates of o -phenylenediamine with different electron-donating/withdrawing groups were employed to convert CO 2 into high-value heterocyclic benzimidazoles. The optimal reaction conditions were determined by a single factor optimization approach. A series of benzimidazole derivatives were synthesized with a yield of up to 96% under atmospheric pressure, indicating that the catalyst can efficiently fix CO 2 . This work not only designs a simple and low-cost K-CN catalyst but also provides a new pathway for converting CO 2 into valuable benzimidazole derivatives at atmospheric pressure. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Advanced Science
·
2024
·
IF 14.3
Maolin Yang,Ziwei Chen,Zhongyuan Huang,Rui Wang,Wenhai Ji,Dong Zhou,Tao Zeng,Yongsheng Li,Jun Wang,Liguang Wang,Tingting Yang,Yinguo Xiao
The development of the electric vehicle industry has spurred demand for secondary batteries capable of rapid-charging and slow-discharging. Among them, sodium-ion batteries (SIBs) with layered oxide as the cathode exhibit competitive advantages due to their comprehensive electrochemical performance. However, to meet the requirements of rapid-charging and slow-discharging scenarios, it is necessary to further enhance the rate performance of the cathode material to achieve symmetrical capacity at different rates. Simultaneously, minimizing lattice strain during asymmetric electrochemical processes is also significant in alleviating strain accumulation. In this study, the ordered distribution of transition metal layers and the diffusion pathway of sodium ions are optimized through targeted K-doping of sodium layers, leading to a reduction of the diffusion barrier and endowment of prominent rate performance. At a 20C rate, the capacity of the cathode can reach 94% of that at a 0.1C rate. Additionally, the rivet effect of the sodium layers resulted in a global volume strain of only 0.03% for the modified cathode during charging at a 10C rate and discharging at a 1C rate. In summary, high-performance SIBs, with promising prospects for rapid-charging and slow-discharging capability, are obtained through the regulation of sodium layers, opening up new avenues for commercial applications.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Jianghua Wu,Faisal Faiz,Mashkoor Ahmad,Miao Zhengjie,Zha Qiang,Wei Xu,Xiaojin Zhao,Xiaofang Pan,Yasir Faiz
The fabrication of supercapacitors with outstanding performance is presented with a distinct defect-rich nanostructures. A one-pot, energy-efficient method for synthesizing defective manganese dioxide nanowires doped with potassium (K 0.35 MnO 2 ) was developed. The introduction of potassium ions at 35 % birnessite resulted in a significant increase in lattice defects and an improvement in conductivity. Addition of KOH induces a phase transition from α-MnO 2 to δ-MnO 2 . These imperfections result in a greater quantity of active sites, which are crucial for the process of energy storage. The K 0.35 MnO 2 structure demonstrates a 405F/g increased capacity at a current density of 1 A/g. The asymmetric supercapacitor (K 0.35 MnO 2 /AC) that was manufactured exhibits a capacitance of 106.4F/g when operating at 1 A/g, while maintaining a maximum energy density of 71.5 Wh kg −1 and a power density of 672 W kg −1 . Furthermore, 92.7 % of the initial capacitance of the device is retained even after 8,000 cycles at 20 A/g. This study presents novel insights into the production of defective materials for energy storage applications through the utilization of a one-pot process as opposed to the multi-step method. In order to produce high-performance supercapacitors for practical applications, the results indicate that defect engineering is a crucial factor.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2025
·
IF 2.6
Hou Peng-qing,Qu Yingdong,Huang Rui,Tian Xinru,Li Guanglong,Luo Shaohua
Li 2 FeTiO 4 cathode has emerged as a promising option for lithium-ion batteries because of its outstanding capacity and eco-friendly properties. However the abominable conductivity and ion transports hindered its electrochemical performance. In this work, (Li 1-x K x ) 2 FeTiO 4 (LiFT-Kx, x = 0 and 0.01) cathode materials with were successfully synthesized. Remarkably, there was a notable improvement in the properties of interlayer spacing, ionic conductivity and kinetics. As a result, LiFT-K0.01 cathode expressed splendid initial capacitance (108.8 mAh g −1 , 0.05 C), stability (82.9% over 30 cycles), and rate performance (89.8 mAh g −1 , 82.4% of the original values). This work might provide valuable insights for the exploration of lithium storage with excellent long-term stability, and it might open new possibilities for the development of advanced energy storage technologies based on lithium-ion batteries.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Ping Hu,Jun Sun,Bo Ran,Jialin Li,Jialu Fang,Qihua Sun,Ning Tian,Zhaofeng Wu,Haiming Duan
The detection of hydrazine (N 2 H 4 ), a highly toxic and explosive compound, is of paramount importance for ensuring environmental and industrial safety. However, research on chemoresistive gas sensors for N 2 H 4 detection, particularly the underlying mechanisms, remains limited. To address this gap, we have prepared carbon materials with a unique morphology and trace K doping through a simple carbonization process, utilizing raw cotton straw (RCS) as the starting material. The CS-400 sensor obtained under calcination at 400 °C exhibited high sensitivity and selectivity for N 2 H 4 , with a response of 30.6 k% and a detection limit of 0.55 ppm for 500 ppm N 2 H 4 at room temperature. Subsequently, the gas sensing mechanism of the straw-based biochar material was focused on, and the roles of cellulose, hemicellulose and lignin in the RCS were analyzed. The interaction between defects and carrier concentration during pyrolysis was elucidated. First-principles calculations confirmed that trace K doping and surface adsorbed oxygen enhance the adsorption of target gases, thereby improving the sensor performance.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）