Inorganic Chemistry Frontiers
·
2017
·Vol. 4
·期 12
·2088-2096
·
IF 4.036
Benxia Li,Renshan Wang,Xiankun Shao,Liangzhi Shao,Baoshan Zhang
In this work, a new design of ternary core–shell nanostructures of Au@ZnO–Pd was demonstrated to realize the synergetic utilization of a plasmonic effect and an electron-trapping co-catalyst for enhanced photocatalytic performance. In the ternary hybrid nanostructures, ZnO provides photo-generated carriers with higher redox ability, under UV-visible light, and Au nanocrystals perform the plasmonic hot electron injection as well as the local electromagnetic field enhancement of ZnO photoexcitation. Meanwhile, the Pd NPs can efficiently trap the generated electrons to govern the directional separation of the charge carriers. The efficient charge carrier separation in the ternary hybrid nanostructures was confirmed by steady-state PL spectra, time-resolved PL decay spectra, and transient photocurrent responses. The photocatalytic activity of the Au@ZnO–Pd nanostructures was evaluated by photodegrading phenol and methylene blue, respectively, under simulated sunlight (λ = 360–780 nm), and the results showed that the Au@ZnO–Pd nanostructures gained a great enhancement of photocatalysis compared with ZnO, ZnO–Pd and Au@ZnO. Moreover, the effect of Pd loading content in the Au@ZnO–Pd nanostructures on the photocatalytic efficiency was studied within a certain range, indicating that the Au@ZnO–Pd photocatalyst with ∼1.8 wt% Pd loading exhibited the best photocatalytic activities for photodegrading both phenol and methylene blue. The generation and effect of active species in the photocatalytic process were investigated using ESR testing and radical scavenging experiments. As a consequence, the integration of the ternary Au@ZnO–Pd core–shell nanostructures could achieve collective effects to greatly increase the photocatalytic efficiency.
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Scientific Reports
·
2015
·Vol. 5
·期 1
·1-7
·
IF 5.578
Liao Peng,Al-Ani Yasir,Malik Ismael Zainab,Wu Xiaohui
A recently developed Pd-based electro-Fenton (E-Fenton) process enables efficient in situ remediation of organic contaminants in groundwater. In the process, H 2 O 2 , Fe(II) and acidic conditions (~pH 3) are produced in situ to facilitate the decontamination, but the role of ubiquitous natural organic matters (NOM) remain unclear. This study investigated the effect of Aldrich humic acid (HA) on the transformation of toluene by the Pd-based E-Fenton process. At pH 3 with 50 mA current, the presence of HA promoted the efficiency of toluene transformation, with pseudo-first-order rate constants increase from 0.01 to 0.016 as the HA concentration increases from 0 to 20 mg/L. The HA-enhanced toluene transformation was attributed to the accelerated thermal reduction of Fe(III) to Fe(II), which led to production of more hydroxyl radicals. The correlation of the rate constants of toluene transformation and HA decomposition validated hydroxyl radical (·OH) as the predominant reactive species for HA decomposition. The finding of this study highlighted that application of the novel Pd-based E-Fenton process in groundwater remediation may not be concerned by the fouling from humic substances.
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ChemSusChem
·
2014
·Vol. 8
·期 2
·260-263
·
IF 7.117
Yu-ling Qin,Ya-cheng Liu,Fei Liang,Li-min Wang
Graphical Twin alloy—twin performance : A simple method is employed to prepare Pd–Co-based nanoparticles that exhibit high catalytic performance toward formic acid decomposition and methanol oxidation. The Pd 3d binding energy decreases owing to the presence of Co, which gives rise to the improved catalytic activity and selectivity toward FA dehydrogenation at room temperature and electrocatalytic performance in methanol oxidation. Formic acid (FA) and methanol, as convenient hydrogen-containing materials, are most widely used for fuel cells. However, using suitable and low-cost catalysts to further improve their energy performance still is a matter of great significance. Herein, PdCo and PdCo@Pd nanocatalysts (NCs) are successfully prepared by the facile method. Pd 3d binding energy decreases due to the presence of Co. Consequently, PdCo@Pd NCs exhibit high catalytic activity and selectivity toward FA dehydrogenation at room temperature. The gas-generation rate at 30 min is 65.4 L h −1 g −1 . PdCo/C has the worst catalytic performance in this reaction, despite the fact that it has a high gas-generation rate in the initial 30 min. Furthermore, both PdCo and PdCo@Pd NCs have enhanced electrocatalytic performance toward methanol oxidation. Their maximum currents are 966 and 1205 mA mg −1 , respectively, which is much higher than monometallic Pd/C.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2014
·
IF 6.007
Xingfa Li,Xin Liu,Lili Xu,Yuezhong Wen,Jianqing Ma,Zucheng Wu
Heterogeneous Pd catalytic Fenton-like systems with in-situ-generated H 2 O 2 have recently gained significant attention for wastewater treatment. Intense research efforts have been focused on developing highly efficient Fenton-like catalysts. It is known that nanoparticle size and appropriate coordination of active compositions are important for the fabrication of a highly efficient multicomponent catalyst. Unfortunately, effects of these factors on Fenton-like reaction are still unknown. To decipher the puzzle, we designed multicomponent Pd/PdO/Fe 2 O 3 nanoparticles in SBA-15 (denoted as FePd-SBA) as a Fenton-like catalyst which possesses uniform and highly dispersed nanoparticles (small size about 5 nm) in space-confined channels of SBA-15. The fabricated catalyst shows high catalytic activities in Fenton-like reaction for dye degradation. For example, 98.6% removal of dye Acid Red 73 was obtained under in-situ generation of hydrogen peroxide. In contrast, when the catalyst loaded on SiO 2 without channels or pores (FePd–SiO 2 ) was prepared, and compared with FePd–SBA, FePd–SiO 2 showed noticeably poor performance (51.6%) under same conditions. Obviously, such a difference in results is due to the confinement effect of SBA-15 porous channels. It was also found that Fe and Pd played important roles in the synergistic effect, that is, Pd worked in in-situ H 2 O 2 generation and Fe species worked in decompose H 2 O 2 to degrade organic pollutants. When we applied this catalyst for Fenton-like reaction with addition of H 2 O 2 , it was also found that Pd and PdO played important roles and the synergistic effect between Fe and Pd species actually existed in dye removal. The unique nanostructure makes the catalyst to be a novel and welcoming choice for H 2 O 2 favorite reactions.
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ACS Applied Materials & Interfaces
·
2015
·
IF 6.723
Jiangbo Xi,Yan Zhang,Ning Wang,Lin Wang,Zheye Zhang,Fei Xiao,Shuai Wang
Recent progress in the in situ molecular detection of living cells has attracted tremendous research interests due to its great significance in biochemical, physiological, and pathological investigation. Especially for the electrochemical detection of hydrogen peroxide (H2O2) released by living cells, the highly efficient and cost-effective electrocatalysts are highly desirable. In this work, we develop a novel type of microporous Co3O4 hollow nanospheres containing encapsulated Pd nanoparticles (Pd@Co3O4). Owing to the synergy effect between the permeable microporous Co3O4 shell and the ultrafine Pd nanoparticles that encapsulated in it, the resultant Pd@Co3O4 based electrode exhibits excellent electrochemical sensor performance toward H2O2, even when the content of Pd in Pd@Co3O4 hollow nanospheres is as low as 1.14 wt %, which enable it be used for real-time tracking of the secretion of H2O2 in different types of living human cells.
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CHEMICAL ENGINEERING JOURNAL
·
2013
·
IF 3.473
Na Li,Jingjing Du,Lijian Xu,Jianxiong Xu,Tie-hong Chen
Synthesis of hollow hydridosilica nanoparticles with mesoporous shell (HMHNs) employing a mixture of cationic fluorocarbon surfactant (FC-04) and nonionic triblock copolymer surfactant (P123) as template and triethoxysilane as silica precursor is reported. It is found that the content of the FC-04 in the surfactant mixture greatly influences the aggregation state of the FC-04 and P123 surfactant template and therefore influences the morphology of the synthesized hydridosilica nanoparticles. HMHNs can be synthesized with proper amount of FC-04 surfactants due to the formation of FC-04 and P123 complex micelle, where FC-04 surfactant locates at the outer shell and the P123 constructs the inner core. Ascribed to the inherent hydride sites within the HMHNs, facile immobilization of Pd nanoparticles is achieved by using HMHNs as both the reducing agent and scaffold. The lesser processes produce some smaller Pd nanoparticles (2–3 nm) within the pore voids and relatively larger Pd nanoparticles (10–15 nm) on the outer surfaces of HMHNs. The catalytic hydrogenation of 4-nitrophenol demonstrates that the heterogeneous Pd catalyst is efficient.
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CATALYSIS TODAY
·
2013
·
IF 2.98
Tong Zhang,Xiongfu Zhang,Xinjuan Yan,Lu Lin,Haiou Liu,Jieshan Qiu,King Lun Yeung
A well-designed Pd/ZSM-5@ZIF-8 core–shell structure has been prepared by application of a combination of seed-induction synthesis strategy and self-assembly synthesis techniques. First, uniform ZSM-5 particles with micron size and high crystallinity were prepared from organic-template-free gel systems containing 200 nm ZSM-5 seeds and exchanged with Pd(NO 3 ) 2 aqueous solution. Then incompatibility between the Pd/ZSM-5 core material and ZIF-8 shell precursor was circumvented by surface modification using a layer by layer self-assembly of polyelectrolyte, followed by a subsequent two-step temperature synthesis process inducing the formation of continuous and well-intergrown ZIF-8 shell. Thickness of ZIF-8 shell can be simply tuned by monitoring the assembly cycles. Furthermore, hydrogenations of 1-hexene and cyclohexene were chosen as model reactions to evaluate the catalytic behavior of the Pd/ZSM-5@ZIF-8 core–shell architecture and tert-dodecylthiol was used as a poison to test its anti-poisoning ability. Results show that such core–shell architecture exhibits excellent poison resistance and selectivity control properties for the hydrogenation reactions and can be potentially used as a membrane reactor in the field of heterogeneous catalysis.
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Journal of Physical Chemistry C
·
2013
·
IF 4.814
Yibo Hu,Kai Tao,Chunzheng Wu,Chen Zhou,Hongfeng Yin,Shenghu Zhou
Pd@SiO2 core–shell nanoparticles were successfully synthesized by a sol–gel method. Tetradecyl trimethyl ammonium bromide capped Pd nanoparticles were coated with SiO2 through the hydrolysis of tetraethylorthosilicate. The as-synthesized Pd@SiO2 particles consist of Pd cores with a particle size of 3.7 nm and SiO2 shells with a thickness from 10 to 30 nm at different synthetic conditions. The Pd@SiO2 nanocatalysts with 1.9–2.4 nm mesoporous SiO2 shells were generated after removal of tetradecyl trimethyl ammonium bromide from Pd@SiO2 core–shell particles by calcination and following H2 reduction. The relevant characterizations such as XRD, TEM, FT-IR, and BET were carried out for Pd@SiO2 particles, and the results showed that the Pd@SiO2 nanocatalysts were highly stable with the protection of silica shells, and the Pd cores did not increase during thermal treatment and H2 reduction. The studies of catalytic CO oxidation at high temperatures and hydrogenation of nitrobenzene with H2 were tested for Pd@SiO2 nanocatalysts, and the results indicated that Pd@SiO2 nanocatalysts were stable at high temperatures and highly active and stable for hydrogenation of nitrobenzene even after long time use.
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GREEN CHEMISTRY
·
2014
·Vol. 16
·期 9
·4371-4377
·
IF 6.852
Mingming Li,Xuan Xu,Yutong Gong,Zhongzhe Wei,Zhaoyin Hou,Haoran Li,Yong Wang
A novel and sustainable synthesis of a Pd/CN@MgO catalyst is presented here, offering a bifunctional catalyst with high catalytic activity towards a tandem aldol condensation–hydrogenation reaction of furfural with acetone in a one-pot reactor. The incorporation of biomass based hydrophilic N-containing carbon (CN) in the catalyst provides a subtle but elegant method to control the good water dispersibility, the reaction stability, and the ultrafine dispersion of palladium particles (2.2 nm in average size) in the bifunctional catalyst Pd/CN@MgO. With such improved features, an impressive 99% furfural conversion and 95% selectivity for the hydrogenated products (saturated ketones) was obtained by using Pd/CN@MgO as a novel bifunctional catalyst in the reported tandem reaction. This catalyst design strategy and the high efficiency of the catalyst in the reported system offer potential for the preparation of bi/multifunctional catalysts and the one-pot synthesis of bioderived intermediates.
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ACS Catalysis
·
2015
·
IF 9.312
Peipei Zhang,Yibo Hu,Baihai Li,Qiuju Zhang,Chen Zhou,Hongbo Yu,Xuejun Zhang,Liang Chen,Bryan Eichhorn,Shenghu Zhou
This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for p-chloronitrobenzene hydrogenation with H2. The 6–8 nm Pd@Pt octahedral NPs are prepared by a sequential reduction method, and the characterization results confirm that Pd@Pt octahedral NPs with one to four atomic Pt layers can be controllably synthesized. The Pd@Pt octahedral NPs with one atomic Pt layer demonstrate excellent structural stability with the maintenance of core–shell structures as well as high catalytic stability during cycle to cycle catalytic p-chloronitrobenzene hydrogenation reactions. The alumina-supported Pd@Pt octahedral NPs illustrate a superior catalytic performance relative to individual Pt and Pd and their physical mixtures. Theoretical calculations by density functional theory suggest that the unexpected structural stability for Pd@Pt octahedral NPs with thin Pt shells and their corresponding catalytic stability during hydrogenation reactions can be ascribed to the strong binding between Pt surfaces and reactants/products in catalytic reactions. The enhanced catalytic performance of Pd@Pt octahedral NPs possibly originates from the core–shell interaction, which adjusts the electronic state of surface Pt atoms to be suitable for selective p-chloronitrobenzene hydrogenation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Hu Li,Wenfeng Zhao,Zhen Fang
Liquid furanic hydrocarbons, a class of biomass-based fuels and chemicals, are typically required to achieve moderate product selectivity and yield under harsh conditions (e.g., high temperature and H 2 pressure) involving multi-step processes over different catalysts. In this study, a single-step catalytic process was developed for direct conversion of various saccharides to furanic biofuels such as 2,5-dimethylfuran and 2-methylfuran with high yields (>95%) at 110–130 °C. The negatively charged hydride (H − ) of readily available polymethylhydrosiloxane (PMHS) acting as green H-donor over hydrophobic Pd nanoparticles did not obstruct upstream reactions (e.g., hydrolysis, isomerization and dehydration) for the in situ formation of furanic aldehydes/alcohols from sugars, and could selectively facilitate the subsequent hydrodeoxygenation of carbonyl and hydroxyl groups other than the furanic ring in one pot, as clarified by deuterium-labeling study. Importantly, the unreduced Pd(II) nanocatalysts also exhibited comparable performance in the selective hydrodeoxygenation reaction. Moreover, the catalytic strategy was extended to various carboxides for quantitative production of corresponding furanic/aromatic hydrocarbons at room temperature that were more pronounced than previously reported results, and the optimal Pd/MIL-53(Al) coated with polydimethylsiloxane (Pd/MIL-53(Al)-P) was highly stable with little deactivation and Pd leaching for at least five consecutive cycles.
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APPLIED ORGANOMETALLIC CHEMISTRY
·
2017
·Vol. 31
·期 12
·e3889
·
IF 2.319
Tao Feng,Ranxiao Tang,Ningzhao Shang,Cheng Feng,Shutao Gao,Chun Wang
A facile and efficient method for facilitating hydrogen generation from formaldehyde aqueous solution was developed using Pd nanoparticles supported on CeO 2 (Pd/CeO 2 ) as the catalyst. The prepared Pd/CeO 2 catalyst exhibited 100% H 2 selectivity and excellent catalytic activity for formaldehyde dehydrogenation with the initial rate of 2089 ml min −1 g Pd −1 at room temperature and atmospheric pressure without any extra additive. The prepared catalyst was stable and reusable, and its catalytic activity kept almost unchanged after it was reused for the fifth run. Therefore, it is considered that this Pd/CeO 2 based hydrogen generation system may serve as an alternative hydrogen supply candidate for practical application.
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