ACS Applied Materials & Interfaces
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2014
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IF 5.9
Zhihua Wang,Jie Xue,Dongmei Han,Fubo Gu
ZnO nanopyramids (NPys) with exposed crystal facets of {101̅1} were synthesized via a one-step solvothermal method, having a uniform size with a hexagonal edge length of ∼100 nm and a height of ∼200 nm. Technologies of XRD, TEM, HRTEM, Raman, PL, and XPS were used to characterize the morphological and structural properties of the products, while the corresponding gas sensing properties were determined by using ethanol as the target gas. For the overall goal of defect engineering, the effect of aging temperature on the gas sensing performance of the ZnO NPys was studied. The test results showed that, at the aging temperature of 300 °C, the gas sensing property has been improved to the best, with the fast response-recovery time and the excellent selectivity, because the ZnO300 has the most electron donors for absorbing the largest content of O2–. Model of defect redistribution was used to explicate the changing of the surface defects at different aging temperatures. The findings showed that, in addition to VO, Zni was the dominant defect of the {101̅1} crystal facet. The gas sensing performance of the ZnO NPys was determined by the contents of VO and Zni, with all of the defects redistributed on the surface. All of the results will be noticeable for the improvement of the sensing performance of materials with special crystal facet exposing.
研究领域:
材料科学
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纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Yu Feng,Wei-Li Li,Dan Xu,Yu-Long Qiao,Yang Yu,Yu Zhao,Wei-Dong Fei
The high piezoelectricity of ABO3-type lead-free piezoelectric materials can be achieved with the help of either morphotropic phase boundary (MPB) or polymorphic phase transition (PPT). Here, we propose a new defect engineering route to the excellent piezoelectric properties, in which doped smaller acceptor and donor ions substituting bivalent A-sites are utilized to bring local lattice distortion and lower symmetry. A concrete paradigm is presented, (Li–Al) codoped BaTiO3 perovskite, that exhibits a largely thermo-stable piezoelectric constant (>300 pC/N) and huge mechanical quality factor (>2000). A systematic analysis including theoretical analysis and simulation results indicates that the Li+ and Al3+ ions are inclined to occupy the neighboring A-sites in the lattice and constitute a defect dipole (ionic pairs). The defect dipoles possess a kind of dipole moment which tends to align directionally after thermo-electric treatment. A mechanism related to the defect symmetry principle, phase transition, and defect migration is proposed to explain the outstanding piezoelectric properties. The present study opens a new development window for excellent piezoelectricity and provides a promising route to the potential utilization of lead-free piezoelectrics in high power applications.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Physical Chemistry C
·
2023
·
IF 3.7
Jia Li,Yimin Tang,Xiuwen Wang,Wei Kan,Libin Yang,Xin Jiang,Yukihiro Ozaki,Xiaoxia Han,Bing Zhao
Surface oxygen vacancy defects and energy band defects can be synchronously regulated to accelerate the charge transfer in a semiconductor–molecule system for boosting the surface-enhanced Raman scattering (SERS) performance of a semiconductor. Herein, alkaline earth metal Sr with a low electronegativity and a large atomic radius was selected as a dopant to prepare a Sr-doped TiO2 (SrnTiO2) SERS substrate, in which a simple Sr doping achieves a synchronous regulation of double defects (i.e., surface oxygen vacancy defect and energy level defect of Ti) in TiO2. Abundant surface oxygen vacancies and defect energy levels of Ti are jointly responsible for the greatly enhanced SERS performance of the substrate. On the optimal substrate Sr0.0100TiO2, the minimum detection limit of a nonresonance molecule, 4-mercaptobenzoic acid, can reach 1 × 10–9 M, and the enhancement factor is as high as 9.3 × 106. To the best of our knowledge, this is the highest SERS activity among the reported semiconducting substrates, even comparable to those of precious metals. Moreover, the SrnTiO2 substrate shows an excellent spectral reproducibility and ultrahigh stability, which can withstand the corrosions of strong acid and alkali and even can resist the oxidation of high temperatures for SERS detection.
研究领域:
材料科学
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化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Jinze Lyu,Junxian Gao,Min Zhang,Yanhong Wang,Dandan Hu,Juan Yi,Junbo Zhong,Ji Li,Shuo Wang
The distribution of bulk and surface defects significantly affects the separation and injection of photogenerated charge carriers. In this study, we provide a strategy of SiO 2 -shell-enhanced F modification to optimize the distribution of bulk and surface defects. The effects of SiO 2 coating and F modification on the physical structure, the separation behavior of photogenerated charge carriers, and the photocatalytic activity of P25 were studied by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, surface photovoltage spectroscopy, and toluene degradation experiments. Results showed that the removal rate of toluene over SiO 2 -F-modified P25 was significantly higher than those over P25 and F modified P25. The SiO 2 -shell-enhanced F modification simultaneously increased the content of surface Ti 3+ and reduced the bulk defects, thereby enhancing the separation of charge carriers. Furthermore, F doped at surface exerted a strong catalytic effect on the removal of toluene, whereas F doped in lattice caused the recombination of photogenerated charge carriers. The SiO 2 coating and calcination treatment significantly increased the amount of F ions doped at TiO 2 surface and inhibited F doping in lattice.
研究领域:
环境科学
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材料科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
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2022
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IF 13.7
Jingxuan Zheng,Xiangfeng Peng,Zhao Xu,Junbo Gong,Zhao Wang
Defect engineering is a promising method to solve the inherent low conductivity and limited number of reactive sites of metal oxides as electrocatalysts. High formation energy makes it challenging to controllably produce metal defects in metal oxides. In this study, abundant Co defects were preferentially produced on spinel NiCo2O4 by tuning the M–O bond length and interfering with ionization of the crystal surface. Theoretical calculations and experiments proved that Al doping elongated the Co–O bond and promoted ionization of Co under plasma treatment. Furthermore, Co ions in the crystal lattice were selectively taken away by adding NaOH to combine with surface-ionized metal ions, which facilitated the formation of cobalt defects. The Co defects induced electron delocalization, which effectively increased the carrier concentration and intrinsic conductivity of the catalysts, thereby enhancing the intrinsic OER catalytic activity of NiCo2O4.
研究领域:
材料科学
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电化学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
Laser & Photonics Reviews
·
2025
·
IF 10
Shenao Jiang,Chengxiang Yang,Riming Hu,Shanshan Liu,Wei Liu,Qi You,Xuan Zhou,Mu Liu,Xuchuan Jiang
Self-activated near-infrared (NIR) phosphors are promising candidates for advanced NIR light sources due to their intrinsic non-toxic composition and cost-effectiveness. However, their practical implementation is hindered by low defect concentration, which critically restricts luminescence efficiency. This study introduces a novel defect engineering strategy via interstitial lithium incorporation in BaAl 2 B 2 O 7 (BAB:Li + ), achieving simultaneous enhancement of NIR emission intensity, spectral modulation, and thermal stability. Structural characterization and density functional theory (DFT) calculations reveal that the broad 780 nm emission under 330 nm excitation originates from interstitial oxygen (O i ) defects in the BAB host. Remarkably, through this interstitial-Li induced oxygen defect engineering method, BAB:0.10Li + demonstrates an eight-fold emission intensity increase accompanied by a 72 nm blueshift, compared to the pristine BAB. Thermoluminescence (TL) analysis confirms that the improvement stems from dual key reasons: O i defects concentration and introduction of additional deep traps. The engineered deep traps endow the phosphor with excellent thermal stability, retaining 86% of initial intensity at 150 °C versus 37% for unmodified counterpart. This validates possible applications in night-vision, biological imaging and fingerprint detection. The defect engineering paradigm probably establishes a general approach for developing high-performance self-activated NIR phosphors, opening a new avenue for advanced optical materials design.
研究领域:
材料科学
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固体化学
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光学材料
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无机功能材料
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光电子学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2022
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IF 9.224
Xintong Li,Yizhe Liu,Qidi Sun,Zhuowen Huangfu,Wei-Hsiang Huang,Zilong Wang,Chu-Chen Chueh,Chi-Liang Chen,Zonglong Zhu
Electrocatalytic water splitting is a promising method to generate high-purity hydrogen, yet its efficiency is limited by the large energy barrier of the counter oxygen evolution reaction (OER). NiFe-layered double hydroxides (NiFe LDHs) are considered as promising electrocatalysts, and some studies have indicated that the involved cationic and anionic defects can further promote their electrocatalytic activities. Nevertheless, the inherent relationships between the defective structures and catalytic activities are still unclear. In this work, by alkaline corrosion of NiFeZn LDH and NaBH4 activation, we involved cationic and anionic defects, respectively. In addition, they both promote the electrocatalytic activity of NiFe LDH in OER, and the co-defected NiFe LDH (cd-NiFe LDH–NaBH4) only needs a low overpotential of 205 mV to obtain a current density of 10 mA cm–2. We invested the exact effects of cationic and anionic defects by electrochemical characterizations and X-ray adsorption structure. The results indicate that the effects of cationic and anionic defects are different, and the cationic defects could promote the oxidation process of Ni species in OER, thus facilitating the favored lattice oxygen mechanism routine, while the anionic defects could enhance the reactivity of Fe sites by creating partially filled antibonding states of Fe–O. Our research reveals the origin of the accelerating effects brought by defective sites in NiFe LDH for OER and provides a facile approach to enhance the catalytic properties of noble metal-free electrocatalysts toward OER.
研究领域:
材料科学
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电化学
✓ 已验证
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2023
·Vol. 33
·期 52
·2305935
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IF 19
Guoqiang Zhang,Wei Huang,Yangsen Xu,Yongliang Li,Chuanxin He,Xiangzhong Ren,Peixin Zhang,Hongwei Mi
Many cases of light absorption modification exceeding 700 nm or near-infrared (NIR) light are reported for capturing more than half of the solar energy, however, very few modifications can produce NIR photoactivity due to the inevitably introduced defects-induced non-radiative recombination. Here, taking four kinds of C/O co-doped red polymeric carbon nitride as examples, defect-repairing is carried out using alkali metal molten-salts (LiCl/NaCl and LiCl/KCl) or solid-salt (KCl) to activate their NIR photoactivity. The defect repair results from the passivation of alkali metal valence electron pairing and the formation of crystalline polyheptazine imide structure with more complete polymerization. More importantly, it sharply eliminates bulk defects (such as carbon vacancy and nitrogen vacancy) introduced by C/O co-doping. Since structural defects are inevitably introduced in most photocatalysts during expanding light absorption, this proposed strategy is bound to be universal in suppressing defects-induced non-radiative recombination to activate NIR photoactivity.
研究领域:
材料科学
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光催化
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产品关联
DOI
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
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2019
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IF 6.393
Xiao Wang,Tongkai Wang,Guangkuo Si,Yang Li,Shouwei Zhang,Xiaolong Deng,Xijin Xu
Surface oxygen vacancy defects (OV) are regarded to be beneficial to the gas sensing behavior by significantly improving the carrier density and providing more oxygen adsorption sites. In this work, Ce-doped α-Fe 2 O 3 composites with abundant OV defects were synthesized using an oil bath method assisted with annealing treatment. Morphological characterization results indicate that the lamellar architecture of α-Fe 2 O 3 is transformed to nanospheres composed of massive nanoparticles with small sizes (7–9 nm) after introducing Ce elements. Gas sensing results show that the FeCe10 (Fe/Ce = 10:1) sensors exhibit enhanced acetone sensing response of 26.3–100 ppm gas at the operating temperature of 220 °C toward that of pure α-Fe 2 O 3 . Most importantly, X-ray photoelectron spectroscopy and electron spin resonance spectroscopy results confirm that the sensing responses of Ce-doped α-Fe 2 O 3 sensors are directly related to the OV defects, that is, the larger the quantity of the OV defects, the higher the sensing response. The unpaired electrons trapped in OV defects can provide more active sites for adsorption of oxygen and acetone molecules, resulting in a thicker depletion layer and a higher potential barrier. Our work highlights the decisive role of OV defects in gas sensors, which can also provide a rational approach to boost the sensing performance.
研究领域:
材料科学
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传感器技术
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纳米材料
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表面化学
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半导体物理
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Guoqiang Zhang,Xiaojun Zhang,Yangsen Xu,Peixin Zhang,Yongliang Li,Chuanxin He,Hongwei Mi
The role of defects in photocatalysis is rarely investigated more intuitively from the perspective of defect ionization energy (DIE), although it is the most important parameter for evaluating the depth of defect traps. Here, the crystalline poly(heptazine imide) (PHI) is adopted as an illustrative example to optimize the DIE and charge separation by regulating the carbon doping contents, ultimately activating the near-infrared photocatalytic activity . Shallow defect traps induced by doping (DIE < 25 meV) facilitate charge separation by releasing shallowly trapped carriers. In contrast, deep defect traps (DIE > 25 meV) act as non-radiative recombination centers , causing carrier quenching. More importantly, the non-radiative recombination rate in PHI is 1–2 orders of magnitude faster than the radiative recombination rate , so suppressing non-radiative recombination is more important for improving charge separation efficiency. Our work elucidates the role of defects in photocatalysis more intuitively from the perspective of DIE, and establishes a discernible relationship between DIE and photocatalytic activity .
研究领域:
材料科学
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光催化
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Ke Li,Rongrong Zhang,Ruijie Gao,Guo-Qiang Shen,Lun Pan,Yunduo Yao,Kaihui Yu,Xiangwen Zhang,Ji-Jun Zou
Manganese-cobalt spinel oxides are considered as a class of promising and low-cost electrocatalysts for oxygen reduction reaction (ORR), whose performances largely depend on their electronic structures which can be effectively optimized by defect engineering. Herein, metal defects (manganese vacancies and cobalt vacancies, i.e. V Mn and V Co ) were in-situ introduced into spinel Mn x Co 3-x O 4 via a simple solvothermal treatment followed by thermal calcination. Mn-Co glycerolate precursors not only enable controllable synthesis of spinel oxides with variable metallic ratios, but also play a key role in constructing metal defected crystals for their lamellated structure. As a result of the formation rate difference between manganese and cobalt glycerolate, a unique Mn-enriched surface is formed, leading to the increase of highly active sites for ORR. Importantly, the presence of metal defects, confirmed by XRD (X-ray diffraction), element analysis and XAFS (X-ray absorption fine structure spectroscopy), leads to greatly increased electrical conductivity and O 2 adsorption ability, thus bringing about enhanced ORR activity. Especially, metal-defected Mn 1.5 Co 1.5 O 4 , with the optimal Mn/Co ratio, exhibits comparable activity and superior durability to those of the benchmark Pt/C in ORR and displays excellent discharge performance in Zn-air batteries for practical application. This work provides a new way to optimize the electrocatalytic performance of mixed metal spinel oxides via rational defect engineering.
研究领域:
材料科学
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电化学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
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IF 15.1
Haifei An,Weijian Tian,Xin Lu,Huanmei Yuan,Liyun Yang,Hao Zhang,Haoming Shen,Hao Bai
Adsorbents with high adsorption capacity and high selectivity are crucial for carbon capture, utilization and storage (CCUS) technology applied to industrial flue gas to reduce carbon emissions. In this paper, a defect-rich hierarchical porous Mg-MOF-74 was synthesized successfully with MgCl 2 ·6H 2 O used as a metal source considering that the weak coordination of Cl − may interfere with the normal coordination process of metal centers and organic ligands, which causes the formation of crystal defects. Through the analysis of a series of characterizations, ligand deletion of Mg-MOF-74 prepared with MgCl 2 ·6H 2 O was confirmed, and the deleted ligand was estimated to be approximately 20% compared with the traditional Mg-MOF-74 prepared with Mg(NO 3 ) 2 ·6H 2 O, which led to mesopores accounting for 36.9%, and the width of mesopores reached 13.1 nm. Compared with traditional Mg-MOF-74, the adsorption heat of CO 2 at zero load of the defect-rich hierarchical porous Mg-MOF-74 increased from 36 kJ·mol −1 to 46 kJ·mol −1 , and the saturated adsorption capacity of CO 2 under ambient pressure was improved by 15%. Interestingly, the IAST selective adsorption performance of CO 2 /N 2 was increased by 20 times. Compared with the saturated adsorption capacity for traditional Mg-MOF-74, the equivalent adsorption capacity of hierarchical porous Mg-MOF-74 only needs 17 kPa, indicating that it is suitable for carbon capture operation in a real flue environment. Calculations of density functional theory (DFT) confirmed that the active site of the hierarchical porous Mg-MOF-74 has a lower adsorption energy with CO 2 due to the presence of defects, which is regarded to play a key role in improving the CO 2 capture performance.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
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