查找使用阿拉丁产品的科研文献

Carbon Materials Containing Single-Atom Co–N4 Sites Enable Near-Infrared Photooxidation

Longjian Li,Junhui Wang,Qinhua Zhang,Shuai Wang,Hangkai Zhang,Tao Xing,Mingqing Wang,Mingbo Wu,Zhenxing Wang,Wenting Wu

Near-infrared light occupies 54.3% of the solar spectrum and has greater penetration depth, and its effective utilization is of great significance in the practical application of photocatalysis on a larger scale. However, the development of catalysts that can directly utilize near-infrared light is still a huge challenge. This paper proposes a strategy to directly utilize near-infrared light (excitation wavelength extending to 850 nm) by creating carbon material doped with a high-spin-state Co(II)-Nx single-atom site. In the near-infrared-light-irradiated photooxidation of 1,5-dihydroxynaphthalene, the yield of juglone can reach 45% without a significant decrease, even when the catalytic volume is increased by 20 times, which was much higher than that irradiated by 460 nm wavelength (reduced by about 23%). Our study sets the stage for fabricating stable NIR photocatalysts and provides a solution to directly enhance NIR photooxidation in a large-scale manner.

Axial coordination engineering of atomic Co–N4 sites for exceptional aromatic nitroreduction

Fengliang Cao,Qingshan Zhao,Xiaojie Tan,Libo Wang,Yikun Zhao,Wei Deng,Linjie Zhi,Mingbo Wu

Optimizing the local environment of metal active centers bonded by nitrogen ligands (M−N 4 ) through additional axial coordination provides a promising approach to enhance the reaction kinetics of heterogeneous catalysis. However, achieving precise targeting and construction of efficient active sites remains a major challenge. In this study, under the guidance of density functional theory (DFT) calculations, we precisely position and engineer atomic Co–N 4 active sites with axial O coordination on porous carbon nanosheets (Co 1 /NOC) for boosted aromatic nitroreduction through a novel template-anchoring strategy. The resulting Co 1 /NOC catalyst exhibited unprecedented catalytic activities towards a series of functionalized nitroaromatics with a record overall turnover frequency (TOF) of 38022 h −1 under mild reaction conditions, 7.6- and 38 times higher than that of Co–N 4 sites (Co 1 /NC) and commercial Pd/C catalysts, respectively, standing ahead of the reported catalysts. Targeted DFT calculations reveal that axial oxygen coordination efficiently promotes the electronic delocalization of the Co center, which dramatically facilitates the formation and utilization of reactive H* species, enhances the selective adsorption of nitroaromatics, and accelerates the conversion of aromatic nitroreduction, eventually attaining exceptional catalytic performance. This work offers a new avenue for precisely tailoring the coordination environment of single-atom catalysts to achieve advanced catalytic performance in chemical transformations.

Co/CoSe heterojunction as bifunctional oxygen electrocatalysts for rechargeable Zinc–Air batteries

Feng Zhang,Yu Lei,Jiali Liu,Guang Li,Yangcheng Xie,Lingguang Yi,Tianjing Wu,Xianyou Wang

The construction of suitable heterostructures in materials can tune the Fermi energy levels and electron transport rates of materials to achieve attractive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties. In this study, a catalyst anchored in nitrogen-doped carbon nanowires (NCNW) with a heterogeneous interface of Co and CoSe is constructed to realize high-performance ORR and OER bifunctional catalysis. These Co and CoSe heterostructure interfaces can optimize the adsorption of intermediates. The Co/CoSe@NCNW catalyst performs excellent ORR catalytic activity (E 1/2  = 0.89 V), and good OER activity (potential at 10 mA/cm 2 , E j = 10  = 1.55 V). More importantly, the material shows excellent performance in rechargeable zinc-air batteries (ZABs). The open-circuit voltages of 1.47 and 1.50 V and the peak power densities of 122.56 and 74.49 mW/cm 2 in liquid and solid electrolytes, respectively, are superior to those of the ZABs prepared from noble metals. Consequently, the construction of heterogeneous structures can convincingly boost the commercialization of rechargeable ZABs, and be extended to other fields involving ORR and OER.

Co-gallate MOF Membrane for Efficient Pervaporation Separation of MeOH from MTBE

Qian Wang,Changchao Zhou,Li Shen,Eryue Song,Yu Yang,Haiqian Lian,Rujing Hou,Yichang Pan

The pervaporation (PV) technology is attractive for azeotrope component separation of the MeOH/MTBE mixture due to the reduced energy and cost relative to the traditional ternary distillation process. However, the membrane separation performance is largely affected by its microstructure including pore size and shape as well as its surface properties such as hydrophilicity. Herein, we report a Co-gallate MOF membrane that features preferential adsorption and diffusion of methanol (MeOH) relative to the methyl tert -butyl ether (MTBE) molecules during the PV separation process. The high-quality Co-gallate MOF membrane has been prepared by introducing a regulator of KOH. The MeOH flux of the Co-gallate MOF membrane was 0.565 kg m −2  h −1 and the separation factor was up to 721 at 15 wt% MeOH/MTBE feed composition. It is worth noting that the separation performance exceeds most of the reported membrane materials for MeOH/MTBE separation in the PV process. Furthermore, the separation performance of the Co-gallate MOF membrane for MeOH/MTBE mixtures remained almost unchanged over 70 h, indicating the reliable long-term stability of the membrane. Thus, the Co-gallate MOF membrane demonstrated a potential practical application for MeOH/MTBE separation.

Co–Fe catalyst supported on acidified bentonite for selective hydrogenation of cinnamaldehyde

Haixiang Shi,Yiyuan Xu,Tongming Su,Xuan Luo,Xinling Xie,Zuzeng Qin,Hongbing Ji

The surface acidity and structure of catalysts play crucial roles in cinnamaldehyde (CAL) selective hydrogenation to manufacture cinnamyl alcohol (COL). Herein, a Co–Fe-supported acidified bentonite catalyst (Co–Fe/ACBT) was prepared via sulfuric acid treatment of bentonite (BT) and the traditional impregnation method. The combination study, including FT-IR spectra of adsorbed pyridine and ammonia temperature-programmed desorption (NH3-TPD), showed that Co–Fe/ACBT has vast acidic sites mainly originating from surface unsaturated metal sites of ACBT, which prefer to adsorb polar >CO but not nonpolar >CC<. X-ray photoelectron spectroscopy (XPS) verified that the effect of electron transfer was significantly enhanced when the active metal was loaded on ACBT, leading to an increase in the electron cloud density of the Co species, which promoted the activation of >CO. Due to the modified electronic properties of Co species and abundant acidic sites, Co–Fe/ACBT exhibited a 90.5% conversion and 86.8% hydrogenation selectivity from CAL to COL, which are notably greater than those of the Co–Fe-supported bentonite catalyst (32.0% CAL conversion and 66.4% COL selectivity).

Co Nanoparticles Embedded in N-Doped Carbon Nanotubes for Broadband Microwave Absorption

Suqiong Xu,Peng Liao,Jiawei Zhu,Wei Ling,Xianke Zhang,Jujun Yuan,Chuicai Rong,Xiaoqing Liu,Zuzhou Xiong

Herein, an efficient one-dimensional (1D) N-doped Co/C nanotube absorber was designed by a cobalt source and solvent ratio comodulation strategy. First, we explored the influences of different cobalt sources (CoCl2, Co(OAc)2, Co(NO3)2, and CoSO4) on the morphology and microwave absorption (MA) property, which showed that CoCl2 facilitated the formation of nanotubes with a relatively uniform diameter and length. Notably, the Co/C nanotubes displayed an ultrawide effective absorption bandwidth (EAB) of 6.885 GHz at 2.2 mm when the filling ratio was only 8 wt %. Then, by adjusting the solvent ratio of isopropanol (IPA) and water, Co/C showed a strong absorption of −44.51 dB with an EAB of 5.44 GHz at 2.35 mm. The outstanding MA performance is ascribed to the synergistic effect of dielectric and magnetic components, which is conducive to optimizing the impedance matching, thus broadening the EAB. In addition, the 1D nanostructure is good for constructing three-dimensional (3D) conductive networks and enhancing conductive loss. Since Co nanoparticles are wrapped in carbon nanotubes (CNTs), the confinement effect can effectively prevent the agglomeration of ferromagnetic nanoparticles, adjusting the MA performance. It is worth mentioning that the maximum Radar cross section (RCS) value of Co/C can be reduced by 28.8 dB m2. Furthermore, the RCS values are all lower than −10 dB m2 from −90 to 90° and the minimum RCS value can reach −46.8 dB m2. This work provides a strategy for designing lightweight MA absorbers with strong RL and ultrawide EAB.

Co-Assembled Supramolecular Organohydrogels of Amphiphilic Zwitterion and Polyoxometalate with Controlled Microstructures

Peilin Wei,Yu Duan,Chen Wang,Panpan Sun,Na Sun

The organization of modifiable and functional building components into various superstructures is of great interest due to their broad applications. Supramolecular self-assembly, based on rationally designed building blocks and appropriately utilized driving forces, is a promising and widely used strategy for constructing superstructures with well-defined nanostructures and diverse morphologies across multiple length scales. In this study, two homogeneous organohydrogels with distinct appearances were constructed by simply mixing polyoxometalate (phosphomolybdic acid, HPMo) and a double-tailed zwitterionic quaternary ammonium amphiphile in a binary solvent of water and dimethyl sulfoxide (DMSO). The delicate balance between electrostatic attraction and repulsion of anionic HPMo clusters and zwitterionic structures drove them to co-assemble into homogeneous organohydrogels with diverse microstructures. Notably, the morphologies of the organohydrogels, including unilamellar vesicles, onion-like vesicles, and spherical aggregates, can be controlled by adjusting the ionic interactions between the zwitterionic amphiphiles and phosphomolybdic acid clusters. Furthermore, we observed an organohydrogel fabricated with densely stacked onion-like structures (multilamellar vesicles) consisting of more than a dozen layers at certain proportions. Additionally, the relationships between the self-assembled architectures and the intermolecular interactions among the polyoxometalate, zwitterionic amphiphile, and solvent molecules were elucidated. This study offers valuable insights into the mechanisms of polyoxometalate-zwitterionic amphiphile co-assembly, which are essential for the development of materials with specific structures and emerging functionalities.

CoCeOx-PVP Catalyst for Effective CO-SCR in the Presence of O2

Yuansong Zhou,Fengyu Gao,Lei Yi,Junyi Wang,Honghong Yi,Xiaolong Tang

In an O 2 -containing environment, achieving efficient selective catalytic reduction of nitrogen oxides (NOx) by carbon monoxide (CO) using non-noble metal catalysts remains a formidable challenge. To balance the catalytic oxidation of CO and the catalytic reduction of NOx, we need to develop a catalyst with strong reductibility and weak oxidizability for the CO selective catalytic reduction of NOx (CO-SCR) reaction in the presence of O 2 . In this study, we synthesized the CoCeOx-PVP catalyst via a coprecipitation method and employed various characterization techniques, including BET, SEM, XRD, Raman, XPS, H 2 -TPR, and O 2 -TPD. The analysis results indicate that the addition of polyvinylpyrrolidone (PVP) alters the surface structure of the catalyst, increases the particle size, and enhances the concentration of surface oxygen vacancies. These structural effects facilitate electron circulation and accelerate the migration of oxygen species, thereby improving the catalytic reduction performance of the catalyst and increasing the conversion rate of NOx. At 250 °C and with 5 vol% O 2 , the conversion rates of NOx and CO can attain 98% and 96%, respectively, accompanied by a remarkable N 2 selectivity of 99%. Following a sustained reaction period of 6 h, the conversion efficiencies of both NOx and CO remain above 95%. However, during extended testing periods, as the oxygen vacancies are progressively occupied by O 2 , the oxygen vacancies generated through the reduction of NO with CO fall short of sustaining the CO-SCR reaction over the long haul. Subsequently, the oxidation reactions of NO and CO come to dominate, resulting in a decline in the NOx conversion rate. Notably, the CO conversion rate still maintains 100% at this point. Based on the results of in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) experiments, we proposed a reaction mechanism for the CO-SCR process over the CoCeOx-PVP catalyst under O 2 -containing conditions. This study provides an effective strategy for the application of non-noble metal catalysts in the field of CO-SCR. Although maintaining long-term activity of the catalyst remains a challenge in the presence of O 2 , the catalyst in this study exhibits a slower deactivation rate compared to traditional non-noble metal catalysts.

Removal of methylene blue from aqueous solutions using Poly(AA-co-DVB)

Jia Du,Luanluan Zhang,Hejun Gao,Yunwen Liao

High-frequency pulse electrodeposition and characterization of Ni–Co/ZrO2 nanocomposite coatings

Jiang Yancheng,Xu Yunhua,Feng Guitao,Yao Hanchao

Ni–Co/ZrO 2 nanocomposite coatings were produced by high-frequency pulse electrodeposition in a modified Watt’s bath containing ZrO 2 particles. The surface morphology, microstructure, and high temperature oxidation resistance of the coatings were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, and isothermal oxidation tests. It was found that the presence of ZrO 2 particles resulted in changes in the morphology and structure of the coatings. The results also confirmed the nanostructure and uniform distribution of ZrO 2 particles of Ni–Co/ZrO 2 nanocomposite coatings. The addition of ZrO 2 did not change the preferred orientation (200), but remarkably affected the relative intensity of planes of Ni–Co alloy. The influence of duty cycle, average current density, and frequency on the amount of incorporated ZrO 2 particles in the Ni–Co/ZrO 2 nanocomposite has been also investigated. The Ni–Co/ZrO 2 nanocomposite coatings with highest ZrO 2 content (11.6 wt%) were prepared under the condition of duty cycle of 40 %, average current density of 5 A dm −2 , and frequency of 100 kHz. Moreover, the embedded ZrO 2 particles significantly improved the high temperature oxidation resistance of Ni–Co alloy coatings. The oxidation rate of Ni–Co/ZrO 2 nanocomposite coatings decreased with increasing the ZrO 2 content of the coatings.

Poly(lactide-co-glycolide)/Hydroxyapatite Porous Scaffold with Microchannels for Bone Regeneration

Ning Zhang,Yang Wang,Wenpeng Xu,Yong Hu,Jianxun Ding

Mass transfer restrictions of scaffolds are currently hindering the development of three-dimensional (3D), clinically viable, and tissue-engineered constructs. For this situation, a 3D poly(lactide-co-glycolide)/hydroxyapatite porous scaffold, which was very favorable for the transfer of nutrients to and waste products from the cells in the pores, was developed in this study. The 3D scaffold had an innovative structure, including macropores with diameters of 300–450 μm for cell ingrowth and microchannels with diameters of 2–4 μm for nutrition and waste exchange. The mechanical strength in wet state was strong enough to offer structural support. The typical structure was more beneficial for the attachment, proliferation, and differentiation of rabbit bone marrow mesenchymal stem cells (rBMSCs). The alkaline phosphatase (ALP) activity and calcium (Ca) deposition were evaluated on the differentiation of rBMSCs, and the results indicated that the microchannel structure was very favorable for differentiating rBMSCs into maturing osteoblasts. For repairing rabbit radius defectsin vivo, there was rapid healing in the defects treated with the 3D porous scaffold with microchannels, where the bridging by a large bony callus was observed at 12 weeks post-surgery. Based on the results, the 3D porous scaffold with microchannels was a promising candidate for bone defect repair.Keywords:poly(lactide-co-glycolide);hydroxyapatite;porous scaffold;microchannel;cell ingrowth;mass exchange;bone tissue engineering

Large-Scale Colloidal Synthesis of Co-doped Cu2SnSe3 Nanocrystals for Thermoelectric Applications

Zhang Aijuan,Chen Qiufan,Yao Wei,Yang Dingfeng,Wang Guoyu,Zhou Xiaoyuan

The large-scale colloidal synthesis and thermoelectric (TE) properties of Co-doped Cu 2 SnSe 3 (CCTSe) alloys are investigated for the first time. The TE properties of the CCTSe bulks were measured in the temperature range from 300 K to 715 K. A large increment in the Seebeck coefficient and a dramatic reduction in the lattice thermal conductivity was observed in CCTSe compounds, and the dimensionless TE figure␣of merit ZT reaches a peak value of 0.63 at 715 K. These observations demonstrate an exciting scientific opportunity to raise the figure-of-merit of colloidally synthesized quaternary chalcogenide nanocrystals via optimized doping.