Molecular Catalysis
·
2024
·
IF 3.9
Kaili Wang,Tingting Zhou,Jia He,Zhen Cao,Zaiyong Jiang
Pt based electrocatalysts are considered as very promising for methanol oxidation reaction (MOR). Especially, the PtRu alloy catalysts has attracted more and more attentions. However, the catalytic efficiency of PtRu electrocatalyst is seriously hampered originated from the poisoning effect of CO* intermediate during MOR process. Herein, we have regulated the Pt/Ru atom ratio and controlled the morphology to optimize electronic structures of the alloy for achieving excellent MOR performance. The obtained Pt 2 Ru 1 alloy nanowires display the most negative peak potential of CO oxidation in contrast to commercial Pt/C, PtRu/C catalysts, Pt 3 Ru 1 and Pt 1 Ru 1 alloy nanowires, indicating an excellent anti CO poisoning activity. In addition, the adsorption capacity of OH* on Pt 2 Ru 1 alloy nanowires is obviously improved compared to commercial Pt/C and PtRu/C electrocatalysts, which is in favor of the oxidizing of CO* intermediate. Therefore, the Pt 2 Ru 1 alloy nanowires exhibit significantly enhanced specific activity (2.30 mA cm −2 ) and mass activity (1.29 A mg Pt −1 ) towards MOR compared to those of commercial Pt/C and PtRu/C electrocatalysts. The research offers a potential insight for designing highly efficient electrocatalysts for MOR.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2022
·
IF 10.319
Tao Xiang,Peng Du,Zeyun Cai,Kun Li,Weizong Bao,Xinxin Yang,Guoqiang Xie
The contradiction between the strength and ductility of metallic materials is a major scientific problem that has been researched for a long time. Dual-phase equiatomic and non-equiatomic Ti-Zr-Nb-Ta high-entropy alloys (HEAs) with super-high strength and excellent ductility have been successfully developed via mechanical alloying (MA) combined with spark plasma sintering (SPS) technology. This is adjusted by altering the atomic ratios of the different phases. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were performed to confirm the dual-phase microstructure. After the SPS process, the average grain size of the aforementioned equiatomic Ti 25 Zr 25 Nb 25 Ta 25 HEAs (134 ± 50 nm) evaluated by electron back-scattering diffraction (EBSD) is smaller than that of the Ti-Zr-Nb-Ta HEAs (150 µm), which were fabricated using arc melting. According to the Hall-Petch formula, the grain boundary strengthening contribution in the Ti-Zr-Nb-Ta system is 33-fold higher than those fabricated using the arc-melting process. When the alloy phase comprises the equivalent dual-phase, equiatomic Ti 25 Zr 25 Nb 25 Ta 25 HEAs have good comprehensive performance compared to non-equiatomic Ti-Zr-Nb-Ta HEAs prepared using the same process. The yield strength of equiatomic Ti 25 Zr 25 Nb 25 Ta 25 HEAs (2212 ± 38 MPa) is two-fold higher than that of Ti-Zr-Nb-Ta HEAs (1100 ± 90 MPa) fabricated via arc melting. This can be attributed to the ultra-fine grain size. Notably, the equiatomic Ti 25 Zr 25 Nb 25 Ta 25 HEAs possess approximately the same biocompatibility as commercial pure Ti (CP-Ti), indicating that the equiatomic Ti 25 Zr 25 Nb 25 Ta 25 HEAs are provided with a possibility as an advanced biomaterial for the applications of the medical field.
研究领域:
材料科学
·
冶金学
·
生物材料工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Xiao-Yu Lang,Guo-Hua Zhang
Mo 2 FeB 2 powders with different Mo/B atomic ratios (0.9, 1.0, 1.1) were first prepared under vacuum condition using different-sized Mo powder, as well as FeB and B 4 C powders as raw materials. Based on the prepared Mo 2 FeB 2 powders, Mo 2 FeB 2 -based cermets were synthesized at different sintering temperatures. Results indicated the morphology of the hard phase was closely related to the Mo/B atomic ratio. As the Mo/B atomic ratio increased, the degree of anisotropy of the hard phase decreased significantly, and its grain morphology gradually evolved from elongated to nearly equiaxed shape. When the sintering temperature was 1200 °C, the incomplete diffusion of the liquid phase led to the occurrence of “liquid-filled lakes” in some samples, while this phenomenon became weakened after the temperature was increased. The microstructure uniformity was optimal when Mo/B = 0.9, with the hardness of 1227 HV 30 ; while the fracture toughness and transverse fracture strength were optimal when Mo/B = 1.1, reaching 23.8 MPa m 1/2 and 2125.9 MPa, respectively. Annealing twins were observed in the γ-Fe binder phase of sample D, which effectively improved the fracture toughness of the cermet by altering the crystallographic orientation of the binder phase. The cermets prepared from ultrafine Mo powders exhibited better mechanical properties due to grain refinement and low porosity.
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2022
·
IF 24.319
Yueshan Xu,Daoxiong Wu,Peilin Deng,Jing Li,Junming Luo,Qi Chen,Wei Huang,Chong Michael Shim,Chunman Jia,Zhongxin Liu,Yijun Shen,Xinlong Tian
The direct methane (CH 4 ) oxidation to high value-added C1 chemicals is a great promising strategy to explore the CH 4 resource utilization. However, the low activity and selectivity of catalytic performance remains a great conundrum due to the difficulty to activate the C H bond and the unmanageable over oxidation. Herein, Pd x Au y nanowires (NWs) with various Pd/Au atomic ratios are presented as ideal models to explore the atomic-level effect of PdAu atoms for the direct CH 4 oxidation. The influence of reaction parameters are systematically investigated, and Pd 9 Au 1 NWs display a maximum yield of 2890.3 μmol g −1 h −1 with 99% selectivity for the liquid C1 oxygenated products. This enhanced performance is attributed to the combination of one-dimensional structure and the synergistic effect from the suitable portion of Au on Pd sites, which regulates bond strength between adsorbed radicals (•OH, •OOH, •CH 3 ) and PdAu atoms, confirmed by the density function theory calculations.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2022
·
IF 9.794
Jinlong Li,Huiyuan Liu,Weiqi Zhang,Qian Xu,Sae Youn Lee,Narayanamoorthy Bhuvanendran,Huaneng Su
The catalyst layer (CL) is the only electrochemical reaction site in proton exchange membrane fuel cells (PEMFCs), decisive in their performance. Herein, a mild and simplified strategy is implemented into the in-situ growth of Pt–Pd alloy catalysts on the gas diffusion layer (GDL) as the CLs for PEMFCs. Pt/C is used as the nucleation site to assist the in-situ growth of the Pt–Pd CL. The as-prepared Pt–Pd CL behaves as a multi rhombic-pyramidal structure, which are evenly distributed on the GDL surface. The effect of the Pt/Pd atomic ratio on the electrocatalytic activity is investigated through a single-cell performance test, and the optimal atomic ratio is determined to be 1/2, which exhibits excellent cell performance and low activation polarization loss. Meanwhile, the single-cell test results reveal that Pt 1 Pd 2 CL reaches optimal performance at a loading of 0.122 mg cm −2 (∼0.06 mg Pt cm −2 ), with a peak Pt-specific power density of 14.23 W mg −1 (6.81 W mg −1 in PtPd), approximately 3.96 times that of a commercial Pt/C CL (0.2 mg Pt cm −2 ). Furthermore, Pt 1 Pd 2 CL shows significantly better stability than the commercial Pt/C CL, indicating that the in-situ preparation of the Pt-based CL has an excellent prospect for the commercial development of PEMFCs.
研究领域:
材料科学
·
电化学
·
能源工程
·
燃料电池技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Yongbin Wu,Shaobo Han,Yong Li,Wenjie Shen
Monodisperse gold-copper nanocubes and AuCu-cuprous sulfide (Cu 1.96 S) heterodimers were fabricated by a step-wise polyol reduction with the aid of oleylamine and 1-dodecanethiol. The geometric configuration was mediated by simply varying the Cu/Au atomic ratio: Au-Cu cubes with sizes of 6.4 and 4.3 nm were yielded at Cu/Au atomic ratios of 1/3 and 1/1, respectively; while AuCu-Cu 1.96 S heterodimer, consisting of a AuCu cube of 4.6 nm and a Cu 1.96 S sphere of 6.3 nm was obtained at Cu/Au atomic ratio of 3/1. Detailed structural analysis on the intermediate products, collected at different intervals during the synthesis, revealed that small-sized Au seeds formed at 423 K, followed by the growth of Cu and Cu 1.96 S crystals at 473 K. Oleylamine coordinated to Au 3+ and Cu 2+ and thus mediated the particle size; while 1-dodecanethiol bonded to Au 3+ and directed the cubic morphology. Excessive Cu 2+ , at the Cu/Au atomic ratio of 3/1, interacted with 1-dodecanethiol and formed Cu 1.96 S spherical particle that epitaxially grew over the AuCu cube, resulting in a heterodimer structure. Due to the enriched surficial Cu atoms and their electronic interactions with Au atoms, Au-Cu nanocubes and AuCu-Cu 1.96 S heterodimers showed pronounced activities for the catalytic reduction of 4-nitrophenol to 4-aminophenol with NaBH 4 at 298 K.
研究领域:
材料科学
·
纳米技术
·
化学工程
·
催化
✓ 已验证
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Qi Wang,Baker Rhimi,Hui Wang,Chuanyi Wang
To solve the aggregation problem of TiO 2 nanomaterials and improve the catalytic efficiency, F-doped TiO 2 /exfoliated bentonite (TF/EB) composite was prepared by dispersing F-doped TiO 2 (TF) nanoparticles on an exfoliated bentonite (EB) using a facile sol–gel method. The exfoliated bentonite was prepared by liquid-exfoliation method from the natural bentonite (B). The prepared samples were applied for toluene degradation in gas phase under UV and visible light irradiation. The as-prepared TF/EB composite exhibited higher toluene degradation efficiency than that of pure TiO 2 , F-doped TiO 2 and TF/B composite. Results indicated that the calcination temperature and the initial F/Ti atom ratio of reaction precursors greatly affected the photocatalytic activity towards toluene degradation. The best photocatalytic performance was obtained by the sample calcinated at 400 °C with an initial F/Ti atom ratio of 5%. The improved photocatalytic performance is ascribed to a series of benefits introduced by F-doping and exfoliation process. The presence of F - ions increases the percentage of exposed reactive {0 0 1} facets on TiO 2 . Moreover, F - ions incorporated into the TiO 2 lattice generate oxygen vacancies and Ti 3+ defects, which influence the transfer and migration of the photoinduced charge carriers and induce a visible-light photocatalytic activity . Furthermore, the electrostatic interaction of negatively charged exfoliated bentonite surface leads to a more efficient separation of charge carriers.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yuwei Liu,Jingbo Jia,Hongli Zheng,Changfu You,Haiming Wang
Ni-based catalysts derived from Ni-Al-Y layered double hydroxides with various amounts of yttrium were synthesized by a condensation reflux method. At the optimized Al/Y atomic ratio of 24/1, the obtained H-Ni 75 Al 24 Y 1 sample showed the highest CO 2 methanation performance. At a WHSV of 15,000 mL h -1 g -1 and a pressure of 0.1 MPa, the CO 2 conversion reached 84.1% with 100% selectivity to CH 4 at 250°C, which was much higher than that of H-Ni 75 Al 25 (75.7%) prepared by the hydrothermal method. Furthermore, the CO 2 conversion over H-Ni 75 Al 24 Y 1 sample rose to 88.7% at 300°C, which exceeded that of the Y-free counterpart (84.1%). The introduction of Y altered the amount and distribution of basic sites as revealed by CO 2 -TPD and led to smaller size and higher dispersion of Ni as proved by XRD, TEM and XPS. The H 2 -TPR result verified stronger metal-support interaction but higher amount of reducible Ni weakly interacted with the support in Ni 75 Al 24 Y 1 LDH sample compared with the Y-free counterpart. As a result, the dissociation of H 2 over Ni sites and subsequent hydrogenation became faster based on the in situ DRIFTS results. Dual pathways were proposed to illustrate the reaction mechanism of CO 2 methanation.
研究领域:
催化
·
环境化学
·
材料科学
·
化学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Small Structures
·
2022
·Vol. 3
·期 10
·2200078
·
IF 11.343
Danni Wang,Xiaoqiong Du,Biao Zhang
It has been widely recognized that ether electrolytes show great advantages in building robust solid–electrolyte interphases (SEIs) for stable anode performance. However, its extension to the graphite electrode is hampered by the ether solvent cointercalation, leading to a lower capacity and higher potential than those in ester counterparts having neat cation insertion. Herein, the ether solvent molecules by optimizing the O/C atomic ratio through tailoring the end group and chain length are screened. Such a modification alters the solvation strength between K ions and the solvent, which dictates the intercalation behavior in graphite. In particular, an ethylene glycol diethyl ether-derived electrolyte is developed, which prevents the solvent cointercalation and induces the formation of binary intercalation compound KC 8 . Meanwhile, the novel ether electrolyte helps build a uniform and robust SEI, significantly boosting the rate capability and long-term stability of graphite anode. This study resolves the dilemma of ether electrolyte in realizing the stable and high-capacity graphite anode for facilitating its application in potassium-ion batteries.
研究领域:
材料科学
·
电化学
·
电池技术
✓ 已验证
DOI
高影响因子
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