Frontiers of Optoelectronics
·
2023
·Vol. 16
·期 1
·1-11
·
IF 5.4
Zhang Chuancheng,Ding Shoujun,Wang Miaomiao,Ren Hao,Tang Xubing,Zou Yong,Dou Renqin,Liu Wenpeng
Optical thermometry based on the upconversion (UC) luminescence intensity ratio (LIR) has attracted considerable attention because of its feasibility for achievement of accurate non-contact temperature measurement. Compared with traditional UC phosphors, optical thermometry based on UC single crystals can achieve faster response and higher sensitivity due to the stability and high thermal conductivity of the single crystals. In this study, a high-quality 5 at% Yb 3+ and 1 at% Ho 3+ co-doped Gd 0.74 Y 0.2 TaO 4 single crystal was grown by the Czochralski (Cz) method, and the structure of the as-grown crystal was characterized. Importantly, the UC luminescent properties and optical thermometry behaviors of this crystal were revealed. Under 980 nm wavelength excitation, green and red UC luminescence lines at 550 and 650 nm and corresponding to the 5 F 4 / 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 transitions of Ho 3+ , respectively, were observed. The green and red UC emissions involved a two-photon mechanism, as evidenced by the analysis of power-dependent UC emission spectra. The temperature-dependent UC emission spectra were measured in the temperature range of 330–660 K to assess the optical temperature sensing behavior. At 660 K, the maximum relative sensing sensitivity ( S r ) was determined to be 0.0037 K −1 . These results highlight the significant potential of Yb,Ho:GYTO single crystal for optical temperature sensors. Graphical abstract
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Chao Huang,Biao Zhang,Yang Luo,Dezhi Xiao,Kaiwei Tang,Qingdong Ruan,Yixuan Yang,Biao Gao,Paul K. Chu
Low-cost, environmentally friendly, and efficient electrocatalysts are required for large-scale and commercial generation of O 2 and H 2 by the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, composites composed of Co and carbon nanotubes (Co NPs@CNT) are fabricated by one-step chemical vapor deposition (CVD) using commercial Co nanoparticles and benzene as precursors. In the alkaline medium, Co NPs@CNT exhibits a small overpotential of 380 mV at a current density of 10 mA cm −2 , small Tafel slope of 82.2 mV dec −1 , and excellent structural and electrochemical durability and the properties are better than those of most previously reported Co-based electrocatalysts and commercial Co nanoparticles. The CNTs not only provide high conductivity, but also decrease the adsorption energy of OH* on the surface of Co NPs@CNT. The small energy barrier is responsible for the enhanced OER performance of Co NPs@CNT. In addition to the revelation of the synergistic effects between Co and CNTs, our results provide insights into the development of metal-carbon electrocatalysts and the simple and effective strategy described here has large commercial potential.
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Journal of Macromolecular Science Part B-Physics
·
2021
·
IF 1.504
Chenmeng Zhou,Xuzhen Zhang
Acetylated cellulose nanocrystals (ACNC) were prepared by surface modifying cellulose nanocrystals (CNC) with acetic anhydride (AA). By adding ACNC into biodegradable poly(butylene succinate-co-butylene adipate) (PBSA), ACNC/PBSA composites were prepared via a melt blending method. The structure and morphology of the ACNC were analyzed by Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD) analysis, field emission scanning electron microscopy (FE-SEM) and contact angle measurements. The results showed that the CNC were successfully modified by acetic anhydride, while maintaining their original nanosize rod shape of CNC and showing obvious hydrophobicity. SEM images of the ACNC/PBSA composites indicated that the ACNC were homogeneously dispersed in the composites. With increasing ACNC content, the crystalinity, melt viscosity and decomposition starting temperature increased gradually. In addition, the tensile strength of the ACNC/PBSA composites showed a maximum value at a ACNC content of 3.0%, which was 26.3% higher than for pristine PBSA but the elongation at break was 20% lower than for pristine PBSA.
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Journal of Macromolecular Science Part B-Physics
·
2017
·
IF 0.828
Shan Bai,Zhenzhong Ouyang
Direct graft copolymerization of maleic anhydride (MAH) onto poly(D,L-lactide-co-glycolide) (PLGA) was performed by use of benzoyl peroxide (BPO) as initiator. Fourier transform infrared spectra, nuclear magnetic resonance, titration analysis of maleation extent and water contact angle were employed to characterize the obtained MPLGA. The effects of monomer concentration, initiator concentration and reaction temperature on the degree of maleation were investigated. The MPLGA scaffold was obtained by using NaCl as the porogen. The results showed that maleic anhydride was successfully grafted onto the PLGA chains. The monomer and initiator concentrations played an important role in the graft copolymerization; the extent of maleation first increased with increasing content of MAH and BPO and then declined. The extent of maleation continuously increased with increasing temperature to 100°C, and then the rate of increase decreased. The extent of maleation could be controlled in the range from 0.15 to 0.71% by adjusting the graft copolymerization conditions. The introduction of anhydride enhanced the water contact angle of PLGA. The MPLGA scaffold showed a network of interconnected pores ranging from 50 to 300 μm.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2019
·
IF 4.029
Kang Qian,Yubai Pan,Zewang Hu,Xiaopu Chen,Yun Shi,Xin Liu,Haohong Chen,Martin Nikl,Jiang Li
SrHfO 3 :Ce and SrHfO 3 :Ce,Al powders were prepared by the solid-state synthesis using the commercial HfO 2 , SrCO 3 , CeO 2 and α-Al 2 O 3 as the starting materials. All the SrHfO 3 :Ce and SrHfO 3 :Ce,Al powders calcined at different temperatures within 1100 °C–1300 °C for 8 h in air exhibited a pure SrHfO 3 phase. Meanwhile, the effects of different calcination temperatures and co-doped alumina on the microstructure of SrHfO 3 :Ce,Al powders were discussed. SrHfO 3 :Ce and SrHfO 3 :Ce,Al ceramics were successfully fabricated via the vacuum sintering at 1800 °C for 20 h. The alumina acted as the sintering aid, which promoted the densification and eliminated the intragranular pores of SrHfO 3 :Ce,Al ceramics. The charge disbalance was effectively compensated by co-doped alumina. SrHfO 3 :Ce,Al ceramics exhibited a higher light yield of 5700 ph/MeV compared with 4600 ph/MeV obtained in SrHfO 3 :Ce ceramics. The charge traps in ceramics and their effects on scintillation properties were also investigated by thermoluminescence measurement.
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IONICS
·
2024
·Vol. 30
·期 4
·2287-2298
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IF 2.4
Lin Jie,Ding Yihong,Jin Huile,Zeng Tianbiao
The development of inexpensive, highly effective and durable electrocatalysts for hydrogen production via water electrolysis is of paramount importance. Transition metal oxides, owing to their simplicity in preparation and cost-effectiveness, have been widely investigated, particularly cobalt, nickel, and manganese oxides. Inspired by the synergies of the ternary cathode materials of lithium-ion batteries (LiNi x Mn y Co 1- x - y O 2 , NMC), a simple and feasible method was used to prepare a graphite plate as the support, and Ni and Mn were co-doped with Co 3 O 4 as an efficient water decomposition catalyst. Experimental studies indicated that the 10% Ni and 10% Mn co-doped Co 3 O 4 (Co 2.4 Ni 0.3 Mn 0.3 O 4 , CNM-811) exhibited the lowest overpotential in the oxygen evolution reaction (OER), with CNM-811 achieving an overpotential of 338 mV at 30 mA cm −2 in NaOH aqueous solution, the Tafel slope is 79.71 mV dec −1 . In the hydrogen evolution reaction (HER), an overpotential of 190 mV was attained at 10 mA cm −2 . In overall water splitting, a cell voltage of 2.048 V was achieved at 100 mA cm −2 , which was superior to many analogous catalysts reported today.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2018
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IF 3.046
Ting Wang,Qing Ma,S.-H. Song
Pure and Ba-Zr co-doped multiferroic BiFeO 3 nanopowders are synthesized via sol-gel method. X-ray diffraction demonstrates the transformation of crystal structure (from R3c to R3c + P4mm) and the absence of impurity phase. Scanning electron microscopy and transmission electron microscopy indicate that the co-doping leads to a decrease in particle size and the Bi 0.85 Ba 0.15 Fe 0.95 Zr 0.05 sample has a particle size of 30–60 nm. Surprisingly, the room-temperature magnetization hysteresis loops change to be soft ferromagnetic with co-doping. The maximum and remnant magnetizations of the as-prepared nanopowders first increase and then decrease with increasing dopant concentration with the Bi 0.85 Ba 0.15 Fe 0.95 Zr 0.05 sample having the best magnetic properties. The enhanced magnetization is due to the crystal lattice distortion caused by the ionic-radius difference between the substituent and host elements and the suppression of the antiferromagnetic spiral spin structure induced by the size effect of the nanopowders.
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高影响因子
CHEMICAL PHYSICS LETTERS
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2020
·
IF 2.029
Jiaqin Liu,Chen Zhou,Wenzhe Yue,Bo Yan,Yichao Lin,Aisheng Huang
A facile and green template-free hydrothermal method was conducted to controllably synthesize spinel type cobalt oxides (Co 3 O 4 ) with cube, truncated octahedron and octahedron morphologies. The catalytic performance over various shapes of catalysts was investigated towards CO oxidation. Among of them, the Co 3 O 4 cube performs the best catalytic activity, which can even be comparable to those of certain noble metal catalysts. The phenomenon might be ascribed to the synergistic effects of exposed Co 3+ active sites and surface oxygen distribution on the surface of the catalyst. The results may provide significant insights for the fabrication of metal oxide catalysts for CO oxidation .
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Ruinan Wang,Shuang Ni,Gang Liu,Xiaoxiang Xu
In this work, we have applied microstructure management and doping techniques to conventional wide band gap semiconductor CaTiO 3 with the aim to improve its light absorption and photocatalytic activity. A series of La/Cr co-doping hollow CaTiO 3 cubes have been successfully prepared by a template-free hydrothermal method. Their crystal structures, microstructures, optical absorption and photocatalytic hydrogen production have been systematically investigated. Our results suggest that hollow CaTiO 3 owns a higher light absorption than solid one and demonstrates a much better photocatalytic activity both under full range (λ ≥ 250 nm) and visible light illumination (λ ≥ 400 nm). These improvements probably originate from the peculiar hollow microstructures that increase photon-matter interactions and shorten the charge migration pathways. The photocatalytic activity for hydrogen production has been further studied by varying the La/Cr content in CaTiO 3 . An optimal doping point at 5% La/Cr doping level has been reached for full range illumination with apparent quantum efficiency approaching ∼2.41%. Nevertheless, the activity under visible light illumination shows a clear dependence on doping level with highest apparent quantum efficiency ∼0.40% at 20% La/Cr doping level. DFT calculations reveal the critical role of Cr in forming a new spin-polarized valence band inside the original band gap of CaTiO 3 therefore is responsible for band gap reduction and visible light photocatalysis. This work here highlights the importance of microstructure control to the photocatalytic performance and shall shed a light on the design and development of efficient photocatalytic materials/systems.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 6
·1-11
·
IF 2.8
Zhang Zhengyu,Yang Yujie,Chen Congliang,Chen Dongyang,Zhang Yingming,Meng Yuting,Li Hao
In this study, Ni–Zn–Co ferrite doped with (Al 3+ ) was synthesized by solid-phase synthesis method and its structure was analyzed. By analyzing the X-ray diffraction (XRD) data, it was explained that the Ni 0.45 Zn 0.40 Co 0.15 Fe 2-x Al x O 4 (0 ≤ x ≤ 0.15) ferrite has a single-spinel structure with FD-3 m space group. Additionally, by analyzing the XRD data, it is found that the lattice constant is the largest when Al 3+ is undoped. The range of lattice constant is (8.3751 ~ 8.3900) Å, the range of saturation magnetization ( M s ) is (68.77 ~ 79.39) emu/g, and the range of coercivity ( H c ) is (9.04 ~ 13.10) Oe. When the content of Al 3+ is 0.09, the permeability reaches the highest. In conclusion, the results obtained indicate that this ferrite is suitable for low-frequency electronic devices and also confirm that Fe 3+ was successfully replaced with Al 3+ . This paper provides a new idea for the study of spinel-structured ferrites by doping Al 3+ .
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
·
IF 3.779
Mingye Ding,Chunhua Lu,Le Chen,Zhenguo Ji
Traditional FIR (fluorescence intensity ratio)-based optical thermometers, requiring narrow energy gap between two thermally coupled states (TCS) of single rare-earth ion, have inherent drawbacks including low signal discriminability and large measuring error. To overcome the intrinsic limitation, a new thermometry strategy involving the usage of dual-emitting activators with diverse temperature-dependent emission behaviours has been proposed. Impressively, β-NaYF 4 :Ce 3+ /Tb 3+ phosphor exhibits good temperature sensing performance, excellent signal discriminability and superior thermal stability by using the linearly temperature-dependent FIR between Ce 3+ and Tb 3+ as detecting parameter. Hopefully, the developed dual-emitting sample could have a promising application in self-calibrated luminescent thermometry and this strategy provides a reference for developing high-performance optical thermometers.
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WATER SCIENCE AND TECHNOLOGY
·
2021
·Vol. 84
·期 1
·251-261
·
IF 1.915
Hu Chunlian,Zhang Wei,Chen Yuantao,Ye Na,YangJi DaWa,Jia Haizhe,Shen Yanting,Song Minna
Here adsorption studies were proposed on a carboxylated sludge biochar (CSB) material modified by HNO 3 to assess its capacity in the removal of cobalt from aqueous solution. The as-prepared sludge biochar material was characterized by Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The isotherm process could be well described by the Langmuir isotherm model. The adsorption kinetics indicated that cobalt adsorption followed a pseudo-second-order kinetics model. The mechanism between Co(II) and biochar involved electrostatic interaction, ion exchange, surface complexation and physical function. The adsorption capacity on CSB was as high as 72.27 mg·g −1 , surpassing original sludge biochar (SB) as CSB had abundant oxygen-containing functional groups and many hydroxyls, plus the BET surface areas increased when SB was modified by HNO 3 , which stimulated adsorption effect. Therefore, this work shows that CSB could be used as an efficient adsorbent to remove Co(II) in wastewater. The material has abundant oxygen-containing functional groups, which are beneficial for binding Co(II). The isotherm process could be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The adsorbent has an efficient adsorption capacity for Co(II), as high as 72.27 mg·g −1 .
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