APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Hongming Zhang,Lu Zhang,Ismael A. Rodríguez-Pérez,Wenkang Miao,Kangli Chen,Wenfeng Wang,Yuan Li,Shumin Han
Sodium borohydride (NaBH 4 ) is widely identified as a promising hydrogen storage material, therefore, developing a catalyst with high efficiency for hydrogen production is an important subject for development and utilization of hydrogen energy. Meanwhile the hydrolytic mechanism of NaBH 4 needs further study which is helpful for hydrolysis researches. In this study, an efficient catalyst comprising of carbon nanospheres (CNSs) supporting ultrafine bimetallic Pt-Co nanoparticles (CNSs@Pt 0.1 Co 0.9 ) has been successfully synthesized for hydrogen evolution from NaBH 4 hydrolysis. The growth of the Pt-Co nanoparticles on the surface of CNSs is regulated by adjustment of solvent during the preparation. The as-prepared CNSs@Pt 0.1 Co 0.9 catalyst exhibits an outstanding performance in the kinetic and thermodynamic tests with the highest hydrogen generation rate (HGR) of 8943 mL H2 ·min −1 ·g M –1 , initial turnover frequency (TOF) value of 280.1 moL H2 ·min −1 ·mol Pt –1 , and a low activation energy ( E a ) of 38.0 kJ·mol −1 . The hydrolytic mechanism has been surveyed simultaneously by the isotopic tracer method through the mass spectrometric analysis. The catalyst retains extremely high catalytic activity value and the hydrogen generation conversion is still 100% even after five cycles in the catalytic performance tests.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Xueyun Liu,Cuimei Cheng,Na Zeng,Xiaoman Li,Qing Jiao,Changgui Lin,Shixun Dai
In comparison to narrow-band upconversion (UC) luminescence from lanthanide-doped systems, broadband UC emission enables a broad and tailorable emissive color, which is desirable for tunable lasers and multicolor display applications. Herein, dual continuous broadband UC emission covering the visible spectral region at 480–720 nm has been achieved for the first time in Yb 3+ /Mn 2+ co-doped glass ceramics (GCs) functionalized with the precipitation of dual-phase γ -Ga 2 O 3 / β -YF 3 nanocrystals . A tunable UC emissive color from yellowish to orange could be obtained under 980 nm excitation by varying the Mn 2+ doping content and heat treatment temperature of GCs. We ascribe this phenomenon to the typical transition of exchange-coupled Yb 3+ -Mn 2+ dimers in tetrahedral and octahedral ligand environments. The Stokes and power-dependent UC luminescence properties, fluorescence lifetimes, site occupation and the involved UC mechanism are discussed in detail. This research contributes to a better understanding of the UC process between Yb 3+ and Mn 2+ in transparent hosts and provides a novel perspective for designing broadband-emitting UC materials.
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Nano Research
·
2024
·
IF 9.5
Ma Ming,Sun Zhiyi,Deng Ziwei,Li Xiang,Zhang Fang,Chen Wenxing
As a new water treatment technology, Fenton-like reaction has great potential. In this study, we successfully prepared an excellent Fenton-like catalyst, which is composed of cobalt monoatoms and asymmetric subnanoclusters (labeled CoSA/Clu-C 2 N), and exhibits excellent peroxymonosulfate (PMS) activation reactivity. By directly comparing the catalytic properties of CoSA-C 2 N and CoSA/Clu-C 2 N, the synergistic effects of coasymmetric Co subclusters and Co atoms on the activation of PMS and degradation of organic micropollutants were investigated. The results showed that CoSA/Clu-C 2 N had higher degradation rates of carbamazepine (CBZ), antipyrine (AT) and chlorobenzoic acid (CA) when combined with active oxidant PMS. The cyclic frequency of CBZ was 5.4 min −1 , which was twice as high as the catalytic constant of CoSA-C 2 N (2.4 min −1 ). The results show that CoSA/Clu-C 2 N cobalt subnanoclusters and cobalt single atom can synergistically improve the catalytic performance of activated PMS oxidation of micropollutants in water. In addition, electron paramagnetic resonance (EPR) technology has proved that the introduction of Co subnano clusters in CoSA/Clu-C 2 N is conducive to the production of singlet oxygen ( 1 O 2 ), thereby improving the efficiency of pollutant oxidation. This work lays a solid foundation for the future design of advanced multifunctional catalysts by carefully regulating and combining monmetallic atoms and metal subnanoclusters.
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Nanomaterials
·
2022
·Vol. 12
·期 16
·2839
·
IF 5.719
Yuruo Zheng,Ghulam Hussain,Shuyi Li,Shanta Batool,Xiawa Wang
In this work, nanoparticles of Co1−xRexFe2O4and CoFe2−xRexO4(0 ≤ x ≤ 0.05) were synthesized by the sol-gel method. The Rietveld refinement analysis of XRD and Raman data revealed that all of the prepared samples were single phase with a cubic spinel-type structure. With the substitution of Re, the lattice parameters were slightly increased, and Raman spectra peak positions corresponding to the movement of the tetrahedral sublattice shifted to a higher energy position. Furthermore, Raman spectra showed the splitting of T2gmode into branches, indicating the presence of different cations at crystallographic A- and B-sites. The SEM micrograph confirms that surface Re exchange changes the coordination environment of metals and induces Fe-site structure distortion, thereby revealing more active sites for reactions and indicating the bulk sample’s porous and agglomerated morphology. The vibrating sample magnetometer (VSM) results demonstrated that the synthesized nanoparticles of all samples were ferromagnetic across the entire temperature range of 300–4 K. The estimated magnetic parameters, such as the saturation magnetization, remanent magnetization, coercivity, blocking temperature (TB), and magnetic anisotropy, were found to reduce for the Co-site doping with the increasing doping ratio of Re, while in the Fe site, they enhanced with the increasing doping ratio. The ZFC-FC magnetization curve revealed the presence of spin-glass-like behavior due to the strong dipole–dipole interactions in these ferrite nanoparticles over the whole temperature range. Finally, the dielectric constant (εr′) and dielectric loss (tanδ) were sharply enhanced at low frequencies, while the AC conductivity increased at high frequencies. The sharp increases at high temperatures are explained by enhancing the barrier for charge mobility at grain boundaries, suggesting that samples were highly resistive. Interestingly, these parameters (εr′,tanδ) were found to be higher for the Fe-site doping with the increasing Re doping ratio compared with the Co site.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 22
·15547-15554
·
IF 3.3
Changyin Zhong,Yifei Yang,Yun Fang,Jun Chen,Bomin Feng,Hongbing Wang,Wenhua Luo,Yunxi Yao
Lanthanum oxide (La2O3) possesses superior reactivity during catalytic hydrogenation, but the intrinsic activity of La2O3 toward H2 adsorption and activation remains unclear. In the present work, we fundamentally investigated hydrogen interaction with Ni-modified La2O3. Hydrogen temperature programmed desorption (H2-TPD) on Ni/La2O3 shows enhanced hydrogen adsorption with a new hydrogen desorption peak at a higher temperature position compared to that on the metallic Ni surfaces. By systematically exploring the desorption experiments, the enhanced H2 adsorption on Ni/La2O3 is due to the oxygen vacancies formed at the metal–oxide interfaces. Hydrogen atoms transfer from Ni surfaces to the oxygen vacancies to form lanthanum oxyhydride species (H–La–O) at the metal–oxide interfaces. The adsorbed hydrogen at the metal–oxide interfaces of Ni/La2O3 results in improved catalytic reactivity in CO2 methanation. Furthermore, the enhanced hydrogen adsorption on the interfacial oxygen vacancies is ubiquitous for La2O3-supported Fe, Co, and Ni nanoparticles. Benefiting from the modification effect of the supported transition metal nanoparticles, the surface oxyhydride species can be formed on La2O3 surfaces, which resembles the recently reported oxyhydride observed on the reducible CeO2 surfaces with abundant surface oxygen vacancies. These findings strengthen our understanding of the surface chemistry of La2O3 and shed new light on the design of highly efficient La2O3-based catalysts with metal–oxide interfaces.
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Molecular Catalysis
·
2023
·
IF 4.6
Wujian Zhang,Weijian Ge,Yiping Jin,Mingming Dang,Panpan Zhang,Wenfeng Han,Ying Li,Zongjian Liu,Haodong Tang
Loaded noble metal redispersion is an important way to solve catalyst sintering. However, how to redisperse at low temperatures or carbon-based noble catalysts is a difficult problem. In this paper, we report this phenomenon occurring on PdCu alloy catalysts, where small-sized PdCu alloys can be realized from sintered large-sized PdCu alloys on carbon supports in a CO/O 2 atmosphere. The mechanism of redispersion is elucidated by XPS, TEM and DFT calculations. The main reason for the redispersion is the formation of the PdCuOx intermediate, which can easily migrate to the nearby catalyst surface and then be reduced to smaller PdCu alloy nanoparticles. This work provides a deeper understanding of the redispersion phenomenon and provides certain applications in industry.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·
IF 7.139
Jianhua Yu,Xiancai Pang,Qunchao Yin,Di Chen,Hongzhou Dong,Qian Zhang,Jing Sui,Lina Sui,Lifeng Dong
Constructing self-supporting porous electrode material with abundant electrochemical active sites can effectively improve the energy storage capacity of supercapacitors . Herein, a novel electrode material (NCS@Co-ZIF/NF) is developed by depositing zeolitic imidazolate frameworks (Co-ZIF) on nickel foams (NF), which is adopted as a precursor (Co-ZIF/NF) to electrodeposit nickel-cobalt sulfides (NCS). The nanosheet arrays with cross-porous structures provide NCS@Co-ZIF/NF with excellent electrochemical characteristics, including a high specific capacity of 144.4 mAh g −1 at the current density of 1 mA cm −2 , 60.5% capacity retention at 50 mA cm −2 , and superb long-term cycle stability. Furthermore, NCS@Co-ZIF/NF//AC hybrid supercapacitor is fabricated by using NCS@Co-ZIF/NF as positive electrodes and activated carbon (AC) as negative electrodes , which exhibits a high energy density of 33.9 Wh kg −1 at a power density of 145 W kg −1 .
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ACS Applied Nano Materials
·
2021
·
IF 5.097
Zhongwen Dong,Chuanyu Yang,Dongpu Zhao,Yanan Wang,Weifeng Chu,Zhaochi Feng,Xiangxue Zhu,Wenjie Xin,Yongchen Shang,Shenglin Liu,Longya Xu
The interzeolite transformation approach has been used extensively for the quick synthesis of zeolites at a lower cost. Herein, an interzeolite transformation method for the quick synthesis of co-crystalline ZSM-5/ZSM-11 (CDM-5) nanoaggregates has been developed by precisely controlling the synthesis parameters and using 1,6-hexamethylenediamine as an organic structure-directing agent. In contrast, the irregular CDM-5 zeolite block obtained from an amorphous aluminosilicate gel takes a longer crystallization time using the conventional method. Combined with the related results of characterization, UV-Raman spectra show that double 6-membered rings in the parent USY zeolite framework are broken, and an ordered aluminosilicate aggregate species (OAAS) containing 4-membered rings (4Rs) are formed during the interzeolite transformation. HRTEM and SEM images demonstrate that the block OAAS is dissolved into amorphous nanoparticles, followed by converting into CDM-5 nanoaggregates. These results reveal that an OAAS is essential for the synthesis of CDM-5 nanoaggregates via the interzeolite transformation method. In addition, the CDM-5 nanoaggregate catalyst exhibits superior stability and resistance to carbon deposition in the alkylation reaction of benzene with ethanol compared with the irregular block CDM-5 catalyst.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Siqi Liu,Wandi Kuang,Xiangjian Meng,Weiliang Qi,Samira Adimi,Haichuan Guo,Xuyun Guo,Erum Pervaiz,Ye Zhu,Dongfeng Xue,Minghui Yang
Low solar-to-fuel conversion in conventional semiconductor-based photocatalysts limits their commercial applications. Searching for highly efficient cost-effective co-catalysts is desirable for the development of artificial photosynthesis systems. In this work, we report a simple yet efficient electrostatic self-assembly process to synthesize one-dimensional Co 4 N-WN x -CdS composites for visible light-driven hydrogen evolution in pure water. Biphasic transition metal nitrides Co 4 N-WN x with high conductivity and enriched active sites leads to multi-level electrons transfer and lower over-potential for hydrogen production. Co 4 N-WN x -CdS composite, with optimized wt%, exhibits the highest rate of photocatalytic hydrogen evolution (14.42 mmol g −1 h −1 ) under vacuum condition. This rate is ~ 8 times higher than that of the Pt-CdS composite (1.78 mmol g −1 h −1 ).
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MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2011
·Vol. 212
·期 23
·2589-2593
·
IF 2.437
Hongjun Yang,Manqing Yan,Stergios Pispas,Guangzhao Zhang
Poly[(ethylene carbonate)- co -(ethylene oxide)] is synthesized by ROP of 1,3-dioxolan-2-one using 1- tert -butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ5,Λ5-catenadiphosphazene as the catalyst. NMR spectroscopy shows that the copolymer chain consists of EO-EC-EO-EO sequences. GPC measurements indicate a PDI of 1.43–1.66 and show that the molecular weight increases with monomer conversion. Thermal analysis demonstrates that the copolymer is amorphous with a glass transition temperature of about –42 °C and an onset decomposition temperature of about 200 °C.
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高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Haiyan He,Ping Yang,Jia Li,Ruixia Shi,Ling Chen,Aiyu Zhang,Yuanna Zhu
CeO 2 nanostructures with various morphologies were prepared through controlling preparation conditions via a hydrothermal method without any surfactants and templates. Cerium acetate, cerium chloride and cerium nitrate were used as cerium precursors to investigate the influence of anions on the growth process of CeO 2 nanostructures. The morphology evolution of CeO 2 and Ce(OH) 3 nanostructures indicates that the anions play an important role for the growth kinetics of resulting samples. Cl − and Ac − ions promoted the formation of one dementional (1D) CeO 2 nanostructures such as nanowires, nanorods and nano hexagonal prisms, while the oxidizing anion NO 3 - facilitated the synthesis of CeO 2 nanocubes. The hydrothermal reaction temperature is another key to govern the morphologies of CeO 2 nanostructures. The formation process of the nanostructures was explored and the possible growth mechanism was discussed. The variety of CeO 2 nanostructures represented inequable catalytic performance for CO oxidation . Because of different surface areas and structures, CeO 2 nanowires revealed the best catalysis performance while that of the nanocubes is the worst.
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ChemistrySelect
·
2023
·Vol. 8
·期 48
·e202301171
·
IF 2.1
Xinyu Wang,Lu Zhang,Guojun Yuan,Jianliang Bai,Yaqing Zhu,Lili Ren
Graphical The mechanism diagram demonstrates that the hydrodechlorination (HDC) reaction of carbon, oxygen co-doped MoP catalyst for trichloroethylene (TCE) shown as the above. Trichloroethylene (TCE) plays an important role in industrial production. However, humans are now suffering the effects of trichloroethylene being released directly into the environment. Therefore, it is urgent to explore effective methods for the degradation of trichloroethylene. Hydrodechlorination (HDC) reaction is considered a green, beneficial and promising technology due to its high selectivity, environmental tenderness and product recovery. Noble metal catalysts are considered as the benchmark catalysts for catalytic processes, but their wide application is limited by their low abundance and low stability. Phosphide has been paid more and more attention in HDC field because of its excellent catalytic performance. In view of the important role of O in the catalytic process, the preparation of C, O co-doped MoP was realized through the co-modification of EDTA and glucose. In the case of changing the molar ratio of MoP to the surface modifier, MOP−C−O (50 %) can achieve the best catalytic efficiency. Even compared with some reported catalysts, it has a very large catalytic advantage. In summary, the C, O co-doped MoP catalyst proposed in this paper provides guidance for the preparation of the same type of catalyst. The harms caused by organic chlorides to the human body and the environment make the problem of how to degrade organic chlorides particularly urgent. Phosphides have gradually attracted attention in HDC due to their high catalytic performance. In view of the important role of O in catalytic process, the preparation of C, O co-doped MoP was achieved by the synergistic modification of EDTA and glucose. Compared with unmodified MoP, the doping of carbon and oxygen in MoP−C−O ensure that more active sites are exposed on the surface. At the same time, the high dispersion of MoP on the carbon matrix increases the specific surface area of MoP−C−O, which is more conducive to the adsorption of reactants on the surface, thereby effectively improving the catalytic activity of the modified MoP−C−O. In the case of changing the molar ratio of MoP and surface modifier, the best activity of MoP−C−O (50 %) reaches 57.80 %, which is 2.3 times higher than that of MoP catalyst.
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