ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Yiping Wu,Meng Wu,Shiwei Yang,Cong He,Chunwen Ye,Yanjie Zhang
Herein, a series of Mn-activated ZnGa2O4 (ZGO) phosphors have been developed for multifunctional applications. The characteristic green and red emission at 503 and 668 nm of Mn-activated ZGO phosphors can be observed under excitation of 247 and 375 nm, respectively, attributed to the partial oxidation of Mn2+ ions resulting in the coexistence of Mn2+ and Mn4+ ions in the host lattice. The valence modulation of Mn content not only realizes the adjustment of red and green luminescence intensity but also achieves the management of persistent luminescence time and thermo-luminescence time. Further, the codoping of Mg2+ could transform the position occupancy preference of Mn and effectively facilitate the conversion of Mn2+ to Mn4+, leading to the regulation of the valence state of manganese ions. Surprisingly, the existence of Mg2+ ions broadens the emission band of Mn4+ and enhances the photoluminescence intensity to 3.8 times, which can be ascribed to the weakened crystal field leading to the downward shift of the 4T2 energy level and the increase of Mn4+ concentration. For this valence modulation behavior, two different hypotheses about the occupancy of Mg2+ have been proposed to explain the corresponding phenomenon. Finally, the potential applications of the synthesized phosphors have been explored in advanced anticounterfeiting strategies, information storage, and plant lighting field.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Energy Materials
·
2021
·
IF 6.024
Huiyi Zhang,Zeming Wang,Zhe Wang,Liang Wang,Yong Wang
Hydrogen peroxide (H2O2) is a worthy chemical substance with comprehensive applications, but its practical industrial methods involve complex and energy-consuming procedures. Electrocatalytic oxygen reduction for the production of H2O2 is a flexible alternative strategy, which requires a low-cost catalyst with high activity and selectivity for the 2e– ORR pathway. Here, we first present a straightforward and universal one-step hydrothermal method that directly combines Cr-ABIm with commercial carbon black (BP2000) to prepare H2O2 electrochemically with high selectivity and energy saving. A variety of characterization analyses display that the introduction of Cr-ABIm increases the number of defects and active sites and also enlarges the surface area of the catalyst for electrochemical reactions. Importantly, the valence state of Cr is changed (Cr3+ of Cr-ABIm converted to Cr5+) when Cr-ABIm anchors on BP2000, which accelerates the activity of the reduction reaction. The selectivity of the catalyst for H2O2 preparation is also determined by Koutecky–Levich analysis and rotating ring disk electrochemical tests. In a potential range of 0.2–0.7 V (vs reversible hydrogen electrode (RHE)), the electron transfer number of the Cr-ABIm@BP2000 catalyst is on the verge of 2.5, and the electrogenerated yield of H2O2 is 65%. In addition, its mass activity at 0.5 V is up to 7.56 A g–1. Density functional theory (DFT) calculations clarify that suitable N, O coordination on the active surface of BP2000s acquires the changing capacity of the valence state of Cr, thereby regulating the adsorption of intermediate products and endowing it with superior H2O2 performance. It is believed that Cr-ABIm@BP2000 will be a viable electrocatalyst for sustainable in situ generation of H2O2 from oxygen.
研究领域:
化学
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材料科学
·
催化反应
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2020
·Vol. 22
·期 33
·18711-18721
·
IF 3.43
Linghui Zhang,Guoqiang Peng,Yujiang Wang,Tiejun Li,Dan Wang,Lili Han,Zhipeng Ci
The controllable design and precise modulation of the functional properties of materials based on theoretical calculations has always been the goal of materials researchers. Through the comparative analysis of theoretical calculations and experimental phenomena, physical properties, including optical properties, electrical conductivity, and dielectric properties, can be further comprehended. In this work, on the basis of the first-principles calculations of many inorganic compounds, we selected BaSnSi3O9 (BSSO) as the research focus and found that it contained two cationic sites with completely different electronic characteristics. Among them, the electron density of cations at the Ba site shows obvious localization characteristics, whereas the Sn site shows strong interaction with the surrounding environment. This distinct difference in electronic characteristics is very beneficial to the research and design of materials with functional properties. When functional ions are introduced into Ba sites, the relatively complete independence of these ions will be maintained. That is, if an ion with multiple stable valence states is introduced at the Ba site, it will exhibit the coexistence of multiple valence states. However, if an ion is introduced at the Sn site, this ion will lose its independence and exhibit strong interaction with the surrounding crystal field environment. The rare earth element europium (Eu) with two stable divalent and trivalent valence states in its normal state was chosen as a probe to verify the theoretical predictions in this work. According to the calculation results, when Eu occupied the Ba site, the spectrum simultaneously showed the luminescence of Eu3+ and Eu2+, and had a larger luminescence quenching concentration when the influence of defects was ignored. When Eu occupied the Sn lattice site, it only showed the luminescence of Eu3+, and had a lower luminescence quenching concentration due to the attractive effect that the surrounding O atoms had on the Eu electrons. Our research indicates that the experimental results are consistent with the theoretical predictions. This paper analyzes the important role of Eu optical probes in terms of investigating their physical mechanisms and optical properties in detail. It will provide valuable inspiration for theoretical calculations to guide the design of materials and the modulation of their functional properties.
研究领域:
材料科学
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物理化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2018
·Vol. 8
·期 7
·1858-1866
·
IF 5.365
Qingjie Meng,Jiajia Liu,Xiaole Weng,Pengfei Sun,Jawwad A. Darr,Zhongbiao Wu
Noble metals, e.g. Pd, are often made into hybrid or composite catalysts (with less expensive materials) to oxidize industry-source emitted volatile organic compounds (VOCs) at low temperatures. In general, the loadings of these metals should be optimized to reduce costs whilst maintaining activity. There exists the possibility to obtain highly active catalysts with low loadings of noble metals by properly tuning the valence state of the metal(s). However, the relationship between the valence state and its effect on catalyst performance is still a matter of debate. In this article, we used supercritical water (sc-H2O), in the presence of oxidizing or reducing gases, as a feasible reaction medium to synthesize Pd/NiO hybrid nano-catalysts and in situ modify the valence state of Pd. After subjecting the catalysts to a range of analytical techniques, including XRD, H2-TPR, DRIFT, TPSR, etc., we unveiled that Pd0 is more active than PdOx and metal oxides in the catalytic oxidation of toluene. This is mainly because the stabilized Pd0 is capable of activating gaseous oxygen (and toluene) at low temperatures and returning to the original state by toluene even with excess oxygen. Although PdOx could desorb active oxygen under a reducing atmosphere and might assist in the oxygen spillover from NiO, it is difficult to convert into Pd0 in an oxygen-rich environment. The developed Pd0-dominated catalyst was found to be robust and highly active after an ageing test with and without water vapour.
研究领域:
催化化学
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环境科学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2021
·
IF 5.165
Yuanyuan Li,Puxian Xiong,Gaochao Liu,Mingying Peng,Zhijun Ma
Bismuth (Bi)-activated luminescence materials have attracted much attention for their tunable broad emissions ranging from a visible to near-infrared (NIR) region. However, it remains a challenge to regulate the Bi valence state and achieve NIR emission via a facile way. Here, we report the design and preparation of Ba3Sc4O9:Bi phosphors, which emit visible and NIR emissions simultaneously even prepared in the air condition. The self-reduction mechanism of Bi3+ species in Ba3Sc4O9 with a rigid crystal structure is illustrated based on the charge compensation model, and the coexistence of different Bi-active centers, Bi3+ for visible emission, while Bi+ and Bi0 for NIR emission, is confirmed by the spectroscopic data and X-ray photoelectron spectroscopy (XPS) analysis. The enhanced NIR emission was further achieved through controlled reducing treatment and the related mechanism has also been clarified. This work paves a new way to control bismuth valence and tune the emission of Bi-based luminescence materials for emerging photonics applications.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Xiaobin Zhao,Quansheng Wu,Xufeng Zhou,Shanshan Ye,Jianyan Ding
The realization of Eu 3+ reduction and its reduction mechanism have become focal points in the field of WLED phosphor research. In this study, the reduction of Eu 3+ was successfully achieved through cationic substitution strategy by replacing Zr 4+ with Hf 4+ in Na 2 ZrSiO 5 :Eu 3+ . The effects of substituting Hf 4+ for Zr 4+ on the phase, crystal structure, and luminescence properties of Na 2 Zr 1- x Hf x SiO 5 :Eu 0.03 (0 ≤ x ≤ 1) were thoroughly investigated based on Rietveld refinement , spectral data, DFT calculation and electronegativity of ions. Comprehensive consideration was given to the effect of site size change and site reducibility on Eu 3+ reduction. The results demonstrate that the reduction of Eu 3+ in Na 2 Zr 1- x Hf x SiO 5 :Eu 0.03 is attributed to the alteration in inducible effect caused by cationic substitution and the enhancement in site reducibility rather than changes in site size. Therefore, the cationic substitution strategy based on induction effect presents a novel approach for achieving Eu 3+ reduction and offers a new insight into developing and modifying Eu 2+ -activated phosphors.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Boda Ouyang,Fei Li,Zhiyong Zhang,Xiaoyi Xie,Lei Chen,Wenjie Sun,Ming-Lai Fu,Baoling Yuan
Excessive phosphate levels in water bodies can lead to eutrophication, one of persistent environmental pollution problems. Metal-organic frameworks (MOFs) have garnered significant attention as a promising material for phosphorus removal due to their high capacity. However, there are challenges with solid-liquid separation necessitating magnetic modification solutions. The low adsorption capacity of magnetite (Fe 3 O 4 ) for phosphates has a potential negative impact on magnetic composites. To explore solutions that enable magnetic modification without reducing the adsorption capacity, Ce-MOFs@Fe 3 O 4 were successfully prepared. Experimental results showed an increase in adsorption capacity and removal rate post magnetic modification, with the phosphorus saturation adsorption capacity reaching 156.01 mg·g −1 . Further investigations involving the adsorbent dosing, co-existence of ions, and stability tests were conducted to explore the practical applications. The results indicated that Ce-MOFs@Fe 3 O 4 performed well across a wide pH range from 4 to 10 and exhibited excellent selectivity in the presence of SO 4 2- , Cl - , and NO 3 - . Zeta potential, FT-IR, and XPS analysis revealed electrostatic attraction and ligand exchange as the main adsorption mechanisms. Ce (III) species played a crucial role in phosphate binding by forming insoluble CePO 4 . On the contrary, Ce (IV) is not helpful for phosphate removal due to insufficient coordination number. In this study, adding Fe 3 O 4 during synthesis facilitated a substantial increase in Ce (III) content, which enhanced the phosphate adsorption capacity and imparted magnetic properties. Hence, the proposed preparation method could serve as a general magnetic strategy for Ce-based adsorbents, enhancing the phosphorus adsorption capacity.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Materials Reports: Energy
·
2022
·
IF 0
Jiadong Hu,Hao Lu,Mingsong Li,Gang Xiao,Min Li,Xuemei Xiang,Zhisong Lu,Yan Qiao
Glucose fuel cells (GFCs) driven by abiotic catalysts are promising green power sources for portable or wearable devices . In this work, a CoO x incorporated carbon nanofiber (CoO x @CNF) catalyst with mixed valences cobalt oxides have been developed through partial oxidation of pyrolyzed electrospun Co 2+ /poly acrylonitrile fibers. The cobalt valence modulating could be achieved via regulating the incorporation ratio of cobalt acetate in precursors or the oxidation temperature of the pyrolyzed fibers. Electrocatalytic analyses show that the presence of CoO in CoO x @CNF will provide more active sites for glucose electrooxidation, and thus enhance the electrocatalytic performance significantly. As a result, the glucose fuel cell built with the CoO x @CNF anode containing both CoO and Co 3 O 4 delivered a maximum power density of 270 μW cm −2 , which is higher than that of other reported Co 3 O 4 based GFCs. This work provides a simple strategy to develop excellent transition metal catalysts for GFCs to expand their applications in portable and wearable energy devices.
研究领域:
材料科学
·
电化学
·
能源技术
✓ 已验证
DOI
Journal of Materials Chemistry B
·
2019
·Vol. 7
·期 38
·5834-5841
·
IF 5.047
Hongwei Song,Kun Ye,Yinxian Peng,Linjie Wang,Xiangheng Niu
Alkaline phosphatase (ALP) is widely recognized as a significant biomarker for lots of diseases. For this reason, developing effective and simple methods to monitor ALP activity is strongly necessary. Herein, we propose a novel strategy based on the target-induced valence state regulation of oxidase-mimicking Ce-based nanorods for ALP activity sensing. The mixed-valent Ce-based material (MVCM) with a relatively high Ce(IV)/Ce(III) ratio can exhibit good oxidase-like activity to trigger the catalytic oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue TMBox in the presence of O2, resulting in a notable chromogenic reaction. When ALP hydrolyzes ascorbic acid phosphate into ascorbic acid (AA), the formed AA induces the partial reduction of the MVCM to one with a low Ce(IV)/Ce(III) ratio, which shows much less activity to trigger the chromogenic reaction. According to the above principle, a facile colorimetric assay was developed for ALP activity detection, providing a linear range of 0.5–25 U L−1 and a limit of detection of 0.1 U L−1. Besides, the proposed strategy could offer favorable selectivity for ALP activity determination. Accurate sensing of the target in serum was demonstrated by our assay as well, revealing its promise as a reliable tool for clinical diagnosis.
研究领域:
生物化学
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医学诊断
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纳米材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Cleaner Production
·
2021
·
IF 9.297
Jiaojie He,Conghong Pei,Yue Yang,Bo Lai,Yan Sun,Liwei Yang
A series of cerium-based metal-organic frameworks (MOFs) with structural design and valence state modulation were fabricated for effective phosphate uptake, which were named as Ce-BDC-1, Ce-BDC-2 and Ce-BTC-1. The X-ray diffractometer (XRD) pattern revealed that Ce-BTC-1 was highly coordinatively unsaturated MOF. The Brunauer-Emmett-Teller analysis (BET) confirmed that Ce-BDC-1 possessed the largest specific surface area of 1285.57 m 2 /g, two-fold higher than the area of Ce-BTC-1 and thousand times larger than that of Ce-BDC-2. The result of X-ray photoelectron spectroscopy (XPS) demonstrated that the dominant valence state of cerium in Ce-BDC-2 was Ce (Ⅲ), while Ce-BDC-1 and Ce-BTC-1 were totally Ce (Ⅳ)-based materials. Impressively, although the physicochemical characteristics were quite divergent, Ce-BTC-1, Ce-BDC-1 and Ce-BDC-2 showed relatively close phosphate removal capacities (the maximum adsorption capacities of them were 242.0, 254.3 and 218.9 mg/g, respectively). Meanwhile, the variety of structure modification or valence state selection would in return affect their adsorption performances, leading to show their own advantage in different removal characteristics like fast adsorption speed, superb uptake capacity in solution with low or high concentration. This study provided three different strategies for preparing high-effective cerium-based adsorbents and revealed the relationship among physicochemical characteristics, adsorption mechanisms and adsorption performances, which might contribute to the design of new metal-based adsorbents.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2024
·
IF 13
Jun Deng,Limei Qiu,Mudi Xin,Wenhui He,Wenhui Zhao,Juncai Dong,Guangtong Xu
Cu-based metal-organic frameworks (MOFs) have attracted much attention for electrocatalytic CO 2 reduction to high value-added chemicals, but they still suffer from low selectivity and instability. Here, an associative design strategy for the valence and coordination environment of the metal node in Cu-based MOFs is employed to regulate the CO2 electroreduction to ethylene. A novel “reduction-cleavage-recrystallization” method is developed to modulate the Cu(II)-Trimesic acid (BTC) framework to form a Cu(I)-BTC structure enriched with free carboxyl groups in the secondary coordination environment (SCE). In contrast to Cu(II)-BTC, the Cu(I)-BTC shows higher catalytic activity and better ethylene selectivity (≈2.2-fold) for CO 2 electroreduction, which is further enhanced by increasing the content of free carboxyl groups, resulting in ethylene Faraday efficiency of up to 57% and the durability of the catalyst could last for 38 h without performance decline. It indicates that the synergistic effect between Cu(I)-O coordinated structure and free carboxyl groups considerably enhances the dimerization of *CO intermediates and hinders the hydrogenation of *CO intermediates in these competitive pathways. This work unravels the strong dependence of CO 2 electroreduction on the Cu valence state and coordination environment in MOFs and provides a platform for designing highly selective electrocatalytic CO 2 reduction catalysts.
研究领域:
材料科学
·
电化学
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 1
·513-526
·
IF 4.186
Bingheng Sun,Benxue Jiang,Jintai Fan,Le Zhang,Long Zhang
Red-emitting color-convertors have attracted considerable attention for promising applications in solid-state lighting (SSL) to improve color rendition. However, the current nitride and fluoride phosphor powders have encountered several challenges, such as high cost, narrow emission bands, and insufficient stability during operation, which limit the development of high-power full-spectrum SSL. In this study, thermally robust Gd 3 (Al,Ga) 5 O 12 :Mn (GAGG:Mn) solid-solution ceramics (SSCs) with dual wavelength red-emission bands were prepared via an oxygen solid-state sintering reaction. The doped Mn ions occupied octahedral Al 3+ and Ga 3+ sites to generate Mn 4+ luminescent centers with pronounced deep-red emissions peaking at 698 nm ( 2 E → 4 A 2 ), and Mn 2+ luminescent centers with broad red emissions at 628 nm ( 4 T 1 → 6 A 1 ). Because the cationic radius matching effect induced the regulation of valence state of Mn, the photoluminescence of the GAGG:Mn SSCs can be tailored by the substitution of Al 3+ with Ga 3+ . Moreover, the Mn 3+ also existed in the GAGG lattice host, and their concentration decreased with increasing Ga 3+ contents owing to the mismatch of ionic radius between Mn 3+ and Ga 3+ ions. With the optimization of Al/Ga ratio and concentration of Mn ions, a broad emission band ranging from 550 to 800 nm (bandwidth = 250 nm) was achieved from Gd 3 Al 3 Ga 2 O 12 :0.3%Mn SSCs upon 465-nm excitation. Moreover, the GAGG:Mn SSC has over 17-fold enhanced thermal conductivity compared with the corresponding phosphor powder. This paper opens a door of regulating the valence state of luminescence centers with cation substitution and the application of oxide red-emitting color-convertors.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
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