RSC Advances
·
2017
·Vol. 7
·期 64
·40462-40469
·
IF 3.108
Yingxia Wang,Zhong Xiong,Yanzhi Xia
In this work, novel branched palladium–gold (PdAu) bimetallic nanowires supported on graphene (PdAu/graphene) were fabricated at relatively low temperatures for the first time by a one-pot co-reduction method with the aid of poly(diallyldimethyl-ammonium chloride). The structural characteristics of PdAu/graphene were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, high-angle annular dark-field scanning transmission electron microscopy and element mapping observations. The electrochemical properties of the PdAu/graphene were characterised by cyclic voltammetry and chronoamperometry (CA) in the formic acid oxidation reaction. Compared with a commercial Pd/C catalyst, the PdAu/graphene catalyst prepared in this work exhibited enhanced electrocatalytic activity including a higher oxidation current density, enhanced CO tolerance, and a more negative onset potential. Moreover, CA analyses demonstrated that PdAu/graphene shows higher stability than the Pd/C catalyst. The PdAu/graphene catalyst exhibited higher activity and strong poisoning resistance, which could be attributed to its special branched structure from PdAu nanowires.
研究领域:
纳米催化
·
电化学
·
材料科学
·
能源化学
·
表面科学
·
电分析化学
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DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2013
·Vol. 31
·期 3
·371-376
·
IF 0.917
Wei Zhu,Haoyang Wang,Haihui Peng,Guosheng Liu,Yinlong Guo
Pd-catalyzed oxidative coupling reaction was of great importance in the aromatic C H activation and the formation of new C O and C C bonds. Sanford has pioneered practical, directed C H activation reactions employing Pd(OAc) 2 as catalyst since 2004. However, until now, the speculated reactive Pd(IV) transient intermediates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the reactive Pd(IV) transient intermediates in the solutions of Pd(OAc) 2 -catalyzed oxidative coupling reactions. In this study, the Pd(IV) transient intermediates were detected from the solution of Pd(OAc) 2 -catalyzed oxidative coupling reactions by ESI-MS and the MS/MS of the intercepted Pd(IV) transient intermediate in reaction system was the same with the synthesized authentic Pd(IV) complex. Our ESI-MS(/MS) studies confirmed the presence of Pd(IV) reaction transient intermediates. Most interestingly, the MS/MS of Pd(IV) transient intermediates showed the reductive elimination reactivity to Pd(II) complexes with new C O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd(IV) transient intermediates in solution.
研究领域:
有机化学
·
金属有机化学
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分析化学
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催化化学
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质谱学
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DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2015
·Vol. 36
·期 10
·1726-1732
·
IF 1.964
Huanhui Chen,Xiaoci Li,Guoqing Zhao,Hongbo Gu,Zhirong Zhu
The side-chain alkylation of toluene represents a novel, environmentally friendly, and low cost route for the production of styrene . However, the yield of styrene produced in this way is currently low, and the mechanism responsible for the side-chain alkylation of toluene is poorly understood. Furthermore, the reason for the higher catalytic efficiency of CsX over NaX and KX remains unclear. In this work, the free radical mechanism of the side-chain alkylation of toluene over basic zeolite X has been elucidated using quantum chemical calculations , together with isotope tracing experiments and the reaction between p -nitrotoluene and methanol. The adsorption isotherm of methanol showed that Cs + ions could block methanol from accessing the β-cage, which is where the side-chain alkylation reaction occurred. Furthermore, the H–D exchange results between toluene and deuterated toluene (C 6 D 5 CD 3 ) showed that CsX was more efficient as a catalyst than KX for the conversion of toluene to the corresponding benzyl radical (C 6 H 5 CH 2 • ). These two results therefore explain the higher catalytic activity of CsX towards side-chain alkylation than KX. Based on the free radical mechanism, the selectivity of styrene could be increased from 17.4% to 59.4% using CO 2 as carrier gas instead of N 2 .
研究领域:
物理化学
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催化化学
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材料化学
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反应机理
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理论化学
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能源化学
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环境化学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2013
·Vol. 1
·期 35
·10184-10192
·
IF 0
Jie Shao,Xuezhang Xiao,Lixin Chen,Xiulin Fan,Leyuan Han,Shouquan Li,Hongwei Ge,Qidong Wang
A system of 2LiH–MgB2 and its hydrogenated 2LiBH4–MgH2 is an attractive candidate for hydrogen storage. However, its hydriding–dehydriding kinetics have to be further improved for practical application. In the present work, three kinds of Ni–B nanoparticles with different crystalline states and particle sizes were prepared by wet-chemical reduction and mechanochemical methods, and then introduced into a 2LiH–MgB2 composite for catalytic enhancement. The catalytic roles of Ni–B nanoparticles on the hydriding–dehydriding properties were investigated systematically. The results show that all of the Ni–B nanoparticles can significantly enhance the hydriding–dehydriding kinetics of the 2LiH–MgB2 composite, resulting in no incubation period for the formation of MgB2 during dehydrogenation. The more disordered the amorphous structure and the smaller sized the Ni–B particles are, the better the catalytic effect that is obtained. Microstructure analyses clearly reveal the formation of the MgNi3B2 phase in the dehydriding process, which acts as the nucleation agent for MgB2 formation determined by an edge-to-edge model. Directly doping with Ni–B nanoparticles in the 2LiH–MgB2 system shows a higher hydrogen desorption capacity of 9.4 wt% and obtains a better catalytic efficiency than doping with NiCl2.
研究领域:
材料科学
·
储能材料
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无机化学
·
纳米催化
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氢储存
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DOI
JOURNAL OF POWER SOURCES
·
2015
·
IF 6.217
Qin Wang,Yingjun Li,Baocang Liu,Guangran Xu,Geng Zhang,Qi Zhao,Jun Zhang
A series of well-dispersed bimetallic Pd@Pt nanodendrites uniformly supported on XC-72 carbon black are fabricated by using different capping agents. These capping agents are essential for the branched morphology control. However, the surfactant adsorbed on the nanodendrites surface blocks the access of reactant molecules to the active surface sites, and the catalytic activities of these bimetallic nanodendrites are significantly restricted. Herein, a facile reflux procedure to effectively remove the capping agent molecules without significantly affecting their sizes is reported for activating supported nanocatalysts. More significantly, the structure and morphology of the nanodendrites can also be retained, enhancing the numbers of active surface sites, catalytic activity and stability toward methanol and ethanol electro-oxidation reactions. The as-obtained hot water reflux-treated Pd@Pt/C catalyst manifests superior catalytic activity and stability both in terms of surface and mass specific activities, as compared to the untreated catalysts and the commercial Pt/C and Pd/C catalysts. We anticipate that this effective and facile removal method has more general applicability to highly active nanocatalysts prepared with various surfactants, and should lead to improvements in environmental protection and energy production.
研究领域:
纳米催化
·
电化学
·
材料化学
·
能源化学
·
表面科学
·
燃料电池
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2019
·
IF 3.131
Xiaotong Sun,Luting Yan,Runxiang Xu,Mingyuan Xu,Yanyun Zhu
TiO 2 presents a broad application prospect in the field of degradation of environmental pollutants. However, the development of TiO 2 photocatalyst has been limited by two factors, namely, narrow spectral response range and low quantum efficiency . Surface coating can selectively change the physical and chemical properties of core particles, whereas the synergistic action between core and shell can optimize material performance. In this paper, surface modification of titanium dioxide (TiO 2 ) by dopamine polymerization was used to improve its photocatalytic performance. Among polydopamine (PDA)-modified TiO 2 , TiO 2 @PDA-0.4 mg/mL-2 h showed the best degradation rate of Rhodamine B (RhB): the degradation rate reached 99.28% and 77.40% after 1.5 h of ultraviolet–visible (UV–vis) and visible (Vis) light irradiation, respectively. Compared with the uncoated TiO 2 , the degradation rate has shown improvement, especially under Vis light irradiation, with the photocatalytic performance improving by 35.04%. Absorption, emission, and impedance spectra showed that surface modification of TiO 2 with suitable thickness of PDA effectively increased light absorption and promoted separation of photogenerated carriers . High-performance liquid chromatography–mass spectrometry revealed the differences in photocatalytic degradation mechanism of TiO 2 @PDA to RhB under UV–vis and Vis light irradiation. Compared with those under UV–vis light irradiation, the intermediate products under Vis light irradiation are relatively simple. TiO 2 @PDA generated more electrons, which interacted with H 2 O to produce large amounts of ·OH and holes under UV–vis light irradiation in comparison with that under Vis light irradiation. In addition to deacetylation , deamination , and decarboxylation by hydroxylation , excess ·OH in the photocatalytic process would attack benzene rings directly to produce N , N -diethylacetamide.
研究领域:
材料科学
·
环境化学
·
光催化
·
纳米材料
·
表面工程
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DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2021
·Vol. 42
·期 10
·1798-1807
·
IF 8.271
Xiangyong Zhang,Tianying Liu,Ting Guo,Xueying Han,Zongyun Mu,Qiang Chen,Jiangmin Jiang,Jing Yan,Jiaren Yuan,Dezhi Wang,Zhuangzhi Wu,Zongkui Kou
Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level, and provides a good platform to gain deep insights into catalytic reactions . The present work describes, employing ultrafine W 2 C nanoislands (average size: 2.3 nm) monodispersed on the N, P dual-doped carbon frameworks as a model system, how to regulate the atomic phosphorous-mounting effect on the surfaces of W 2 C to derive an active and stable P-mounting W 2 C (WCP) catalyst for both acidic and alkaline hydrogen evolution reaction (HER). Since in situ phosphorus substitution into carbon sites of preformed W 2 C nanoislands gradually proceeds from surfaces to solids, so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk. By this way, the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H 2 s −1 at –200 mV overpotential in acid and base, respectively, which reach up to the several-fold of pure-phase W 2 C (0.01 and 0.05 H 2 s −1 ). Theoretical investigations suggest that compared with solid P doping, the P mounting on W 2 C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier. This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity , and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions .
研究领域:
材料化学
·
电催化
·
纳米材料
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能源科学
·
表面科学
·
理论计算
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DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Hongguan Li,Jing Wang,Ruijuan Qi,Yongfeng Hu,Jing Zhang,Hongbin Zhao,Jiujun Zhang,Yufeng Zhao
Charge and spin manipulations of electrons are considered to be of great significance in boosting the catalytic activity of M N C electrocatalysts. However, to the best of our knowledge, most current studies focus only on the charge engineering, the interplay between spin and charge is not well understood, and the simultaneous manipulation of both charge and spin remains challenging. Herein, we show that the cooperative interplay between charge itineration and spin-polarization of electrons has a profound impact on the catalytic behavior through density functional theory (DFT) calculations for the first time. Following this concept, we report a Fe-Ni atomic pair as a superior bifunctional catalyst for high performance ORR and OER, with a very small potential difference (ΔE) of 0.691 V. We confirm that the coexistence of Fe 3d itinerant charge and moderate spin polarization (magnetic moment: 1.48 μ B ) is responsible for the superior functional catalytic activity for the Fe Ni atomic pairs.
研究领域:
电催化
·
材料化学
·
物理化学
·
纳米催化
·
能源材料
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计算化学
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DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2023
·Vol. 30
·期 50
·108538-108552
·
IF 5.8
Wang Yongqiang,Bai Yibo,Han Che,Li Zaimei,Lun Xiaowen,Zhang Conglu
Graphite-like carbon nitride (g-C 3 N 4 ) is favored for its excellent physicochemical properties. However, the high complexation rate of photogenerated carriers greatly limits its practical applications. Based on this, a novel CQDs-doped carbon nitride nanosheets composite (CNS/CQDs) was prepared and applied to the visible light–induced activation of peroxymonosulfate (PMS) for meloxicam (Mel) and tetracycline (TC) degradation. The photocatalytic degradation of Mel and TC were remarkably promoted in the CNS/CQDs+PMS+vis system. Mel photodegradation of 99.90% was achieved over 30 min with 20 mg CNS/CQDs and 20 mg PMS at pH11. And TC photodegradation of 95.97% was achieved over 45 min with 20 mg CNS/CQDs and 20 mg PMS at nature pH6.5. The TOC mineralization rates of Mel and TC were 75.49% and 52.00%, respectively. The transient photocurrent response and electrochemical impedance measurements (EIS) results indicated that the doping of CQDs could improve the charge transfer efficiency of pure g-C 3 N 4 , and CNS/CQDs had a low charge transfer resistance. Capture experiments and EPR tests explored the effective actives in the CNS/CQDs+PMS+vis system. Possible degradation pathways of Mel were also analyzed. This study provides valid residual drugs degradation under the dual conditions of visible light catalytic oxidation and persulfate oxidation, which will be a novel perspective for advanced oxidation technology to effectively remove organic pollutants from water.
研究领域:
环境科学
·
光催化化学
·
水处理技术
·
纳米材料
·
高级氧化工艺
·
药物代谢
·
环境污染物降解
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DOI
高影响因子
Science China-Materials
·
2021
·Vol. 65
·期 3
·721-731
·
IF 8.273
Xu Hui,Jin Meng,Geng Jing,Zhang Shengbo,Zhang Haimin
The decentralized production of H 2 O 2 via a two-electron oxygen reduction reaction (2e − ORR) has emerged as a promising alternative to the energy-intensive anthraquinone (AQ) process. However, its practical application requires 2e − ORR electrocatalysts with high activity and selectivity. Herein, we report the synthesis of metallic Ni nanoparticles anchored on bacterial cellulose-derived carbon fibers (Ni-NPs/BCCF) via a facile impregnation-pyrolysis method as efficient electrocatalysts for 2e − ORR to H 2 O 2 . By tuning the amount of Ni precursor, the best electrocatalytic performance toward 2e − ORR was achieved for Ni-NPs/BCCF-20.7, affording a high H 2 O 2 selectivity of ∼90% and an onset potential of 0.75 V vs. reversible hydrogen electrode (RHE) in an alkaline electrolyte. Ni-NPs/BCCF-20.7 achieved the largest H 2 O 2 yield rate of 162.7 ± 13.7 mmol g cat −1 h −1 and the highest Faradaic efficiency of 93.9% ± 4.2% at 0.2 and 0.5 V vs. RHE from the bulk ORR system, respectively. Theoretical calculations revealed the more favorable “end-on” adsorption configuration of molecular oxygen on the exposed Ni(111) plane, which can effectively suppress the O-O bond dissociation, resulting in high selectivity for H 2 O 2 generation.
研究领域:
材料化学
·
电化学
·
纳米催化
·
能源科学
·
环境工程
✓ 已验证
DOI
高影响因子
ChemSusChem
·
2019
·Vol. 12
·期 4
·858-865
·
IF 7.804
Xinxin Li,Qingshan Zhao,Xiang Feng,Lei Pan,Zhuangzhuang Wu,Xiaocui Wu,Tianwen Ma,Jialiang Liu,Yuanyuan Pan,Yan Song,Mingbo Wu
Graphical Nitrogen-doped graphene nanoshells supporting palladium nanoparticles (Pd/N-GNS) have been developed as a superior catalyst for the N -allylation reaction. Experimental results and DFT calculations reveal strong metal–support interactions between the pyridinic N and palladium species, which significantly boost the catalytic efficiency and stability of the catalyst. In this study, nitrogen-doped graphene nanoshells (N-GNS) were developed to support palladium nanoparticles (Pd/N-GNS) as an efficient and recyclable catalyst for the N -allylation reaction. N-GNS was synthesized through a facile hard-template method by using petroleum asphalt, followed by nitrogen doping by thermal annealing with urea, the contents and species of which could be altered by the calcination temperature. Palladium nanoparticles (Pd NPs) with an average diameter of 3.3 nm were homogeneously deposited onto the N-GNS support through a mild solvent-growth approach. The Pd/N-GNS exhibited a superior activity towards the N -allylation reaction, 6-fold higher than that of the pristine graphene nanoshells supporting the palladium catalyst. The Pd/N-GNS could be recycled several times without activity deterioration and metal leaching. The catalytic activity showed a linear correlation relationship with the pyridinic N content. Experimental and theoretical studies reveal strong metal–support interactions between the pyridinic N and palladium species, which can downsize the Pd NPs, modulate the electronic properties, and promote the adsorption of reactant, thereby significantly boosting the catalytic efficiency and stability for the N -allylation process. The present work could help unravel the roles of nitrogen-doped carbon supports and provides a feasible strategy to rationally design superior palladium catalysts for chemical transformations.
研究领域:
材料科学
·
催化化学
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产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2013
·Vol. 38
·期 25
·10932-10938
·
IF 3.548
H. Wang,J. Zhang,J.W. Liu,L.Z. Ouyang,M. Zhu
In this study, alkali hydroxides (NaOH, LiOH, KOH) were attempted as new-type catalytic additives to improve the hydrogen storage properties of MgH 2 by ball milling . It is shown that the additives readily react with the MgH 2 to form perovskite-structured NaMgH 3 and KMgH 3 , but not the LiMgH 3 . Although the in-situ formed perovskite hydrides remain stable during hydriding/dehydriding cycles, both NaMgH 3 and KMgH 3 show predominant catalytic role on the hydriding and dehydriding of MgH 2 . In contrast, the LiOH modified MgH 2 presents much inferior sorption kinetics because of the absence of LiMgH 3 . The catalytic mechanism of perovskite hydrides can be explained by the high hydrogen mobility in the perovskite structure . This study shows that such cheap hydroxides could be used as efficient catalysts to improve the hydrogen storage properties of high-capacity metal hydrides and complex hydrides .
研究领域:
材料科学
·
无机化学
·
能源化学
·
氢能存储
·
金属氢化物
·
固态储氢
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）