Nature Catalysis
·
2020
·Vol. 3
·期 4
·411-417
·
IF 30.471
Zhang Xiaoben,Han Shaobo,Zhu Beien,Zhang Guanghui,Li Xiaoyan,Gao Yi,Wu Zhaoxuan,Yang Bing,Liu Yuefeng,Baaziz Walid,Ersen Ovidiu,Gu Meng,Miller Jeffrey T.,Liu Wei
The high catalytic performance of core–shell nanoparticles is usually attributed to their distinct geometric and electronic structures. Here we reveal a dynamic mechanism that overturns this conventional understanding by a direct environmental transmission electron microscopy visualization coupled with multiple state-of-the-art in situ techniques, which include synchrotron X-ray absorption spectroscopy, infrared spectroscopy and theoretical simulations. A Ni–Au catalytic system, which exhibits a highly selective CO production in CO 2 hydrogenation, features an intact ultrathin Au shell over the Ni core before and after the reaction. However, the catalytic performance could not be attributed to the Au shell surface, but rather to the formation of a transient reconstructed alloy surface, promoted by CO adsorption during the reaction. The discovery of such a reversible transformation urges us to reconsider the reaction mechanism beyond the stationary model, and may have important implications not only for core–shell nanoparticles, but also for other well-defined nanocatalysts.
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ACS Catalysis
·
2020
·
IF 12.35
Ji-Xiao Zhao,Chao-Qiu Chen,Cai-Hong Xing,Zhi-Feng Jiao,Meng-Ting Yu,Bing-Bao Mei,Jie Yang,Bai-Yan Zhang,Zheng Jiang,Yong Qin
Precise control of selectivity in hydrogenation reactions is a long-standing challenge. Surface decoration of nanocatalysts with transition-metal oxide nanoparticles (NPs) is an effective strategy to tailor the catalytic selectivity but generally at the expense of activity due to the blocking of active sites. Here, we report that constructing single-site metal oxide modifiers (NiO, CoOx, or FeOx) on supported Au NPs by atomic layer deposition (ALD) can regulate their catalytic selectivity for nitroaromatic hydrogenation. The coverage of single-site metal oxide can be precisely tuned by altering the number of ALD cycles. The Au/TiO2 decorated with five cycles of NiO (Ni: 0.32 wt %) in the style of a single site can efficiently change the product selectivity from azo to azoxy compounds without significantly blocking the surface active sites. The density functional theory calculations indicate that the azoxybenzene bonded to the single-site NiO-decorated Au(111) with a larger adsorption energy, which inhibits the overhydrogenation of azoxybenzene and results in high azoxybenzene selectivity. Our work has demonstrated a general and efficient way to regulate the reaction selectivity of metal nanocatalysts by anchoring single-site metal oxide promoters.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2020
·
IF 3.807
Cong Luo,Jianghua Yang,Jinling Li,Shijie He,Bowen Meng,Tao Shao,Qiankun Zhang,Dongxia Zhang,Xibin Zhou
A strategy for the synthesis of Au@N-CQDs@Pd three-layer core-shell nanoparticles without the use of any surfactant is proposed in this work. Herein, N-doped carbon quantum dots (N-CQDs) are used as the reducing agent, stabilizing agent, and shape-directing agent. The morphology and structure of the final product were characterized by Transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and X-ray powder diffraction (XRD). The electrocatalytic test indicates the as-synthesized Au@N-CQDs@Pd 20 exhibites excellent activity for methanol oxidation in alkaline media, which is approximately 6 times higher than commercial Pd/C. And its resistance to CO and stability are also greatly improved. This work provides a simple and straightforward approach to prepare bimetallic core-shell electrocatalyst by using CQDs with high catalytic activity for alkaline fuel cells .
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NANOTECHNOLOGY
·
2020
·Vol. 31
·期 21
·215606
·
IF 3.551
Haifeng Niu,Jianbo Li,Xuefang Wang,Zhe Qiang,Jie Ren
We demonstrated a simple approach for fabricating Au–Fe3O4/PDA hollow nanoparticles as high-performance catalysts for water purification. The polydopamine (PDA) shell was in situ formed on the silica surface from self-polymerization, which acts as a medium support for coupling with metal ions (for Fe3O4 nanoparticle deposition) as well as a reducing agent and stabilizer for Au nanoparticle reduction and deposition. A step of simultaneous Fe3O4 nanoparticle deposition and silica core removal under alkaline conditions is first introduced in this study. This process significantly simplifies previous strategies which typically require the use of poisonous agents such as hydrogen fluoride or additional complicated post-treatment steps. Under optimized conditions, the Au–Fe3O4/PDA hollow nanoparticles show a high saturation magnetization of 18.8 emu g−1 and an excellent catalytic performance for the rapid reduction of p-nitrophenol with the reaction kinetic constant of 0.34 min−1. This catalyst can be easily recovered using a permanent magnet and recycled eight times with a high catalytic cycle stability. The strategy presented in this work provides a facile and versatile approach towards designing complicated Au–Fe3O4/PDA hollow nanostructures, which might have great potential for many applications within biological, energy, and environmental technologies.
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Journal of Physical Chemistry C
·
2020
·
IF 4.189
Tao Ma,Feng Liang
Bimetallic nanoparticles consisting of gold (Au) and palladium (Pd) have attracted considerable attention because of their effective catalysis for many chemical reactions. They are highly expected to help in the preparation of Au–Pd nanocatalysts with a controllable structure, morphology, and composition. Here, we show that Au–Pd nanostars (NSs) with tunable surface plasmon resonance absorption (from 536 to 583 nm), nanoparticle size, and palladium content (less than 7 wt %) can be obtained by adjusting the ratio of ascorbic acid and chloroauric acid. These synthesized Au–Pd NSs could be utilized efficiently for the reduction of 4-nitrophenol and nitrobenzene and the Suzuki coupling reaction. Their enhanced catalytic activity could be due to their easy accessibility of the active sites, star-like structure, and Pd-rich surface. The systematic synthesis reported in this work will not only give researchers new insights into the controllable preparation of bimetallic nanoparticles but may also inspire further studies of multifunctional nanocatalysts.
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DYES AND PIGMENTS
·
2020
·
IF 4.613
Yuye Chen,Xiu Qin,Chunling Yuan,Rui Shi,Yilin Wang
B, N-doped carbon quantum dots (CQDs) with an emission peak at 490 nm was prepared by a hydrothermal method . It was found that the fluorescence of CQDs could be effectively quenched by Au nanoparticles (AuNPs) with the absorption peak at 520 nm. Thiocholine (TC), which was produced from acetylcholine (ACh) hydrolysis catalyzed by acetylcholinesterase (AChE), could induce the aggregation of AuNPs along with a drop in the absorption at 520 nm and result in the recovery of quenched CQDs fluorescence. When carbaryl was introduced, which inhabited the catalytic activity of AChE, thus the aggregation of AuNPs and the recovery of CQDs fluorescence was decremented. On the basis of above phenomena, we established a colorimetric and fluorescent double reading method for carbaryl determination. Under the optimum conditions, the fluorescence response was strongly correlated with carbaryl concentration in the 0.20–150 μg/L range, and the absorbance response was linearly proportional to the concentration of carbaryl in the range of 0.2–20 μg/L. This method was used to the determination of carbaryl in tap and lake water samples with high precision and accuracy, indicating the potential of the method in practical applications with simple operation, good accuracy and high sensitivity.
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ACS Omega
·
2020
·
IF 2.87
Qing Huang,Yuxia Liu,Cuizhong Zhang,Zhenfa Zhang,Fengping Liu,Jinyun Peng
Owing to the importance of epinephrine as a neurotransmitter and hormone, sensitive methods are required for its detection. We have developed a sensitive photoelectrochemical (PEC) microsensor based on gold quantum dots (Au QDs) decorated on a nickel tetraminophthalocyanine–graphene oxide (NiTAPc-Gr) composite. NiTAPc was covalently attached to the surface of graphene oxide to prepare NiTAPc-Gr, which exhibits remarkable stability and PEC performance. In situ growth of Au QDs on the NiTAPc-Gr surface was achieved using chemical reduction at room temperature. The synthesized materials were characterized by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. Au QDs@NiTAPc-Gr provided a much greater photocurrent than NiTAPc-Gr, making it suitable for the ultrasensitive PEC detection of epinephrine. The proposed PEC strategy exhibited a wide linear range of 0.12–243.9 nM with a low detection limit of 17.9 pM (S/N = 3). Additionally, the fabricated PEC sensor showed excellent sensitivity, remarkable stability, and good selectivity. This simple, fast, and low-cost strategy was successfully applied to the analysis of human serum samples, indicating the potential of this method for clinical detection applications.
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ANALYST
·
2020
·Vol. 145
·期 6
·2191-2196
·
IF 3.978
Fen-Ying Kong,Lei Yao,Xin-Yang Lu,Heng-Ye Li,Zhong-Xia Wang,Hai-Lin Fang,Wei Wang
The Au–Hg amalgam anchored on the surface of reduced graphene oxide nanosheets (Au–Hg/rGO) has been synthesized successfully and characterized by various techniques such as transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The Au–Hg/rGO nanocomposites were found to possess excellent peroxidase-like catalytic activity and can quickly catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB in the presence of H2O2. The obvious color change offered accurate determination of the H2O2 concentration by recording the absorbance at 652 nm using a UV-vis spectrophotometer. The linear response range for H2O2 was from 5 μM to 100 μM and the detection limit was 3.25 μM (S/N = 3). Furthermore, a kinetic study indicated that the catalytic behavior of Au–Hg/rGO nanocomposites followed the typical Michaelis–Menten theory and Au–Hg/rGO nanocomposites showed good affinity for H2O2. We envision that the simple and sensitive colorimetric detection system holds great promising applications in clinical diagnostics and food and environment monitoring.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2021
·
IF 7.46
Jinyu Huang,Hao Liang,Jiexiong Ye,Dongting Jiang,Yiling Sun,Xuejin Li,Youfu Geng,Jiaqi Wang,Zhengfang Qian,Yu Du
Au-loaded ZnO were successfully prepared by means of seed-assisted solvothermal methods. The vertically ordered nanorod arrays are uniformly grown on the Al 2 O 3 substrate. The sensing properties of ZnO and Au-loaded ZnO sensors toward HCHO were investigated. Remarkably, the sensor based on 4 wt%Au-loaded ZnO nanorod arrays exhibits high response, short response and recover times, excellent selectivity, as well as low HCHO detection limit at 70 °C. After the incorporation of Au nanoparticle, the detection limit decreases from 10 ppm to 0.25 ppm, and the response increases more than 20 times under 100 ppm HCHO at 70 °C. Moreover, the mechanism of HCHO sensing with Au-loaded ZnO was explored by the calculations obtained from the first-principle studies.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2019
·Vol. 21
·期 10
·1-10
·
IF 2.009
Jiang Xinde,Wang Zhenxi,Zhang Xiaohang,Jiang Guixian,Peng Yong,Xu Sheng,Cao Meng,Dai Xin,Liu Zuhan,Ma Jianye
A green bioreduction method was used to prepare highly efficient supported TiO 2 photocatalysts with bimetallic (Au-Ag) nanoparticles at room temperature using Cinnamomum camphora leaf extract as both the protective agent and reducing agent. The resulted Au-Ag/TiO 2 exhibits high photocatalytic activity toward the degradation of organic dyes. It was demonstrated that after some of the biomolecules were removed through ionic-liquid extraction and/or calcinations, the Au-Ag/TiO 2 photocatalyst exhibits significantly enhanced catalytic performance toward the degradation of methyl orange compared to the pristine untreated catalyst. As a result, 300 mL of 20 mg/mL methyl orange can be fully degraded in 30 min. These can be explained by the sufficient biomolecules could protect the nanoparticles stay in small size, but excess biomolecules played an unfavorable role in hindering the electron transportation during the catalytic reaction. The low-cost preparation, the high activity, together with the good stability and recyclability make this developed Au-Ag/TiO 2 a promising photocatalyst toward the degradation of wastewater.
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CRYSTENGCOMM
·
2019
·Vol. 21
·期 45
·6935-6944
·
IF 3.382
Qunling Fang,Yuhang Sun,Jinyu Duan,Linfeng Bai,Kezhu Xu,Qinshan Xiong,Huajian Xu,Ken Cham-Fai Leung,Ailing Hui,Shouhu Xuan
Metal–organic framework (MOF)-derived nanostructures exhibit wonderful characteristics and possess broad application potential by modulating the complex composition and inner nanostructure. Although various MOF-based nanocomposites have been successfully developed, a facile method that can easily modulate the structure-dependent chemical components of the MOF-derived hybrids remains a challenge. By coating zeolitic imidazolate framework-8 (ZIF-8) with Au/polydopamine (Au/PDA) via in situ redox-oxidation polymerization of HAuCl4 and dopamine, it was found that the ZIF-8 templates were simultaneously etched off to give Au/PDA hybrid microcapsules with a cubic shape. This one-step sacrificial templating process followed a competing chelation between gold ions and Zn2+ cations to 2-methylimidazole and PDA; thus, both the hollow and the yolk-like hybrid cubic microcapsules were controllably obtained by varying the synthetic dynamics. Owing to the hollow nature, penetrated PDA shell, well-distributed Au nanocrystals, and unique stable nanostructure, the non-spherical Au/PDA hybrid cubic microcapsules showed high performance in catalyzing the reduction of 4-nitrophenol as well as adsorption/release of ibuprofen as a model drug. Moreover, this simple strategy offers a controllable design in developing multifunctional nanocomposites with definite inner nanostructures and activities for nanocatalysis, drug delivery, energy storage etc.
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Small
·
2019
·Vol. 15
·期 6
·1804769
·
IF 10.856
Hongjing Wang,Hongjie Yu,Ziqiang Wang,Yinghao Li,You Xu,Xiaonian Li,Hairong Xue,Liang Wang
Electrochemical reduction of N 2 to NH 3 provides an alternative strategy to replace the industrial Haber–Bosch process for facile and sustainable production of NH 3 . The development of efficient electrocatalysts for the nitrogen reduction reaction (NRR) is highly desired. Herein, a micelle-assisted electrodeposition method is presented for the direct fabrication of porous Au film on Ni foam (pAu/NF). Benefiting from its interconnected porous architectonics, the pAu/NF exhibits superior NRR performance with a high NH 3 yield rate of 9.42 µg h −1 cm −2 and a superior Faradaic efficiency of 13.36% at −0.2 V versus reversible hydrogen electrode under the neutral electrolyte (0.1 m Na 2 SO 4 ). The proposed micelle-assisted electrodeposition strategy is highly valuable for future design of active NRR catalysts with desired compositions toward various electrocatalysis fields.
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