ChemPlusChem
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2020
·Vol. 85
·期 8
·1783-1788
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IF 2.753
Rongxiu Guo,GuangQi He,Lei Liu,Yongjian Ai,Ze-nan Hu,Xinyue Zhang,Haimeng Tian,Hong-bin Sun,Dun Niu,Qionglin Liang
Graphical Four in one : A quaternary-component catalyst containing platinum, copper, and iron, which are supported on Fe 3 O 4 nanospheres can be used in the selective synthesis of symmetrical secondary amines by transfer hydrogenation of nitriles with excellent conversion and selectivity. A variety of nitriles were tested for the synthesis of symmetrical secondary amines, and no hydrogenolysis byproducts were detected. Hydrogenation of nitriles is an efficient and environmentally friendly route to synthesize symmetrical secondary amines, but it usually produces a mixture of amines, imines, and hydrogenolysis by-products. Herein we report a magnetic quaternary-component Pt−CuFe/Fe 3 O 4 nanocatalyst system for the selective synthesis of symmetrical secondary amines with ammonia borane as hydrogen donor. The catalyst with a low Pt loading (0.456 wt%) is the source of the activity, and the d-band electron transfer from Cu to Fe enhances the selectivity. This synergistic effect results in the transformation of benzonitrile to dibenzylamine with excellent conversion (up to 99 %) and nearly quantitative selectivity (up to 96 %) under mild reaction conditions, nevertheless, the reaction TOF is as high as up to 1409.9 h −1 . A variety of nitriles are suitable for the synthesis of symmetrical secondary amines. More importantly, unwanted hydrogenolysis byproducts, especially toluene, is not detected at all. In addition, the catalyst is magnetically recoverable, and it can be reused up to five times.
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Nanoscale
·
2020
·Vol. 12
·期 27
·14615-14625
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IF 6.895
Yaru Bian,Hao Wang,Zhi Gao,Jintang Hu,Dong Liu,Liming Dai
Trifunctional electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are crucial for many electrochemical devices. Herein, novel trifunctional electrocatalysts of a hierarchically-structured Pt/NiO/Ni/CNT with ultrasmall Pt nanoparticles (∼2 nm) were synthesized via substrate-enhanced electroless deposition. The resulting catalysts exhibited a higher ORR activity (half-wave potential at 0.942 V) than that of the benchmark commercial Pt/C (20 wt%) and a similar OER activity (overpotential of 350 mV at 10 mA cm−2) to that of RuO2 in alkaline media. Moreover, the newly-developed Pt/NiO/Ni/CNT catalysts also showed a high mass activity superior to Pt/C towards the HER in both acid and alkaline electrolytes. The Pt/NiO/Ni/CNT catalysts, when used for overall water splitting, self-powered by two Zn–air batteries with the Pt/NiO/Ni/CNT air electrodes connected into series, displayed superb performance with 1.61 V at 10 mA cm−2. This work represents a breakthrough in the development of facile approaches to trifunctional catalysts from low-cost Earth-abundant materials for efficient energy conversion and storage.
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JOURNAL OF HAZARDOUS MATERIALS
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2021
·
IF 10.588
Jie Fan,Yuhang Sun,Mingli Fu,Jiaqi Li,Daiqi Ye
Metal support interactions modulation is one of the effective strategies to enhance the catalytic performance. Herein, we reported that modulating metal support interactions by switching the strength (CO, H 2 , NH 3 ) and temperature (200, 300, 400 °C) of reducing gases is a facile way to improve the catalytic performance of Pt/CeO 2 for toluene oxidation . The distinct reduction treatments will stepwise enhance the reducibility, ratio of Pt 0 and oxygen vacancy concentration, which dominated the activity. The metal support interactions modulation can significantly affect toluene deep oxidation (from benzoate to formate or monodentate carbonate) via enhancing the mobility of surface/lattice oxygen and activation ability towards O 2 molecules, since the main activation sites for O 2 molecules expand from Pt 0 sites to oxygen vacancies and Pt 0 sites with temperature increasing.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2019
·
IF 6.361
Jianguo Yu,Dan Wei,Zhe Zheng,Wenjie Yu,Honghui Shen,Yuning Qu,Shuya Wen,Young-Uk Kwon,Yongnan Zhao
x%Pt-Naf-CV (Pt-Nafion-Cyclic Voltammetry) catalysts with homogeneously distributed platinum nanoparticles and ultra-low Pt loading are successfully synthesized by using a facile potential cycling approach. The as-synthesized 0.8%Pt-Naf-CV catalyst exhibits an enhanced electrocatalytic activity for hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 solution, which obtains a low overpotential of 34 mV at 10 mA cm −2 . The linear sweep voltammetry (LSV) curve of 0.8%Pt-Naf-CV catalyst is almost consistent with that of commercial Pt/C. However, the 0.8%Pt-Naf-CV catalyst displays a more excellent stability and durability in comparison with commercial Pt/C. Besides, the Pt loading of Pt/C (Pt–10 wt%) is about 10 times that of 0.8%Pt-Naf-CV catalyst. The improved electrocatalytic performances are derived from the synergistic effects of Pt and Nafion. The Nafion plays a significant role as a dispersant , carrier and structure directing agent on the morphology and size of the Pt catalyst. This result contributes a promising method to enhance the catalytic activity and reduce the amount of Pt.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2019
·
IF 3.218
Yang Tan,Yan Zhang,Xiuxiu Wang,Lingxing Zeng,Fenqiang Luo,Aihua Liu
Multi-walled carbon nanotubes (CNTs) modified with amorphous nickel coating was reported as a novel support for platinum (Pt) for methanol oxidation reaction (MOR). First, an amorphous nickel coating on pristine CNTs (Ni/CNTs) via a simplified electroless deposition method without sensitization and activation is easily developed. Then, Pt nanoparticles (10 wt%) supported on Ni/CNTs (Pt/Ni/CNTs) were fabricated using a microwave-assisted reduction method. The as-prepared Pt/Ni/CNTs electrocatalyst exhibited higher electrocatalytic activity towards MOR in acidic solution, supported by the fact that its methanol oxidation current density was about 0.38 fold higher than that value of Pt/CNTs. Additionally, the proposed Pt electrocatalyst showed a little better electrocatalytic activity than the Pt/C catalyst containing Pt up to about 20%. Moreover, the Pt/Ni/CNTs also exhibited the best stability during the process of MOR. The improved activity and durability of Pt/Ni/CNTs electrocatalyst can be attributed to a more uniform distribution of Pt nanoparticles as well as the synergistic effect between Pt and amorphous nickel coating. Therefore, the as-prepared Pt/Ni/CNTs electrocatalyst is active and stable, which may be applied to the direct methanol fuel cells with high performance.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Wenhao Gong,Zheng Jiang,Rifeng Wu,Yang Liu,Lei Huang,Ning Hu,Panagiotis Tsiakaras,Pei Kang Shen
Investigating on well-defined structure-engineering and atomic arrangement of fuel cell catalysts with high activity has attracted considerable research interest the last decade. Specially, unique nanostructures, which possess high surface-to-volume ratio and high atomic utilization have been emerged as promising candidate catalysts. Herein, we have successfully synthesized Pt–Ni cross double dumbbell-like nanostructures (Pt-Ni CDDNs) via a facile one-pot synthesis route and a kinetic control with surface capping. It is found that the as-prepared Pt–Ni alloy nanostructures exhibit an enhanced catalytic activity toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in comparison with commercial Pt/C catalysts. The excellent electrooxidation property is attributed to the synergistic effect between Pt and Ni atoms, as well as high specific surface area of dumbbell-like nanostructures with multiple nanosheets . The present work provides new opportunities for the rational design of bimetallic nanomaterials with enhanced catalytic performance.
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RSC Advances
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2019
·Vol. 9
·期 19
·10635-10644
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IF 3.049
Xiaoxu Xuan,Jun Cheng,Xiao Yang,Junhu Zhou,Kefa Cen
Carbon supported nano-metal catalysts are expected to improve CO2 reduction selectivity and efficiency due to the addition of more active sites and enhancement of electron transport ability. In this study, HKUST-1 was pyrolyzed and decorated with Pt to prepare Pt–Cu/C catalysts. The catalytic effect of the catalysts with different Pt contents in the CO2 photoeletrochemical reduction reaction (CO2PRR) were compared. The total carbon atom conversion rate in CO2PRR experiments using Pt–Cu/C catalysts first increased to a peak when using 1.6 wt% Pt–Cu/C catalyst and then decreased with the increase of Pt content. The 1.6 wt% Pt–Cu/C catalyst showed good hydrogen evolution reaction (HER) inhibiting ability compared with other Pt–Cu/C catalysts. Density functional theory (DFT) calculations were conducted to give an insight into the CO2PRR mechanism on some possible active sites in Pt–Cu/C catalysts. The result demonstrated that HER was more likely to be inhibited on the Cu/Pt active surface and at the same time CO2PRR was promoted.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
·
IF 4.084
Zhuojun Duan,Mingyu Pi,Dingke Zhang,Peng Zhang,Junkai Deng,Shijian Chen
To promote hydrogen production through water splitting, novel porous 3D Al doped CoP 3 nanowire arrays on carbon fiber paper are successfully fabricated as an effective self-supported electrode for hydrogen evolution reaction . The results indicate that the electrocatalytic performance of CoP 3 can be dramatically enhanced via Al doping. It only needs an overpotential of only 40 mV to achieve the current density of 10 mA cm −2 with a small Tafel slop of 43 mV dec −1 for the Al (10%)-CoP 3 nanowire arrays. Moreover, the Al (10%)-CoP 3 NAs/CFP exhibit superior HER efficiency to Pt/C film at high overpotentials due to prompt release of hydrogen bubbles on the special nanowire arrays surfaces. This study demonstrates an avenue for further improving the electrocatalytic activity via tuning the electronic structures and adjusting the surface morphologies through heteroatoms doping.
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CATALYSIS TODAY
·
2019
·
IF 4.888
Yiwen Jiang,Ling Zhang,Yiquan Xie,Shichao Han,Qiuyan Zhu,Xiangju Meng,Feng-Shou Xiao
A series of zeolite-supported Pt nanoparticles (Pt/NaZSM-5) have been prepared by adjusting Si/Al ratio of NaZSM-5 zeolite from 60 to pure silica. Catalytic tests in propene oxidation as an important model reaction for removal of hydrocarbons emitted from automobiles during cold-start, show that the catalytic activities significantly increase with Si/Al ratios of NaZSM-5 zeolite in these Pt/NaZSM-5 catalysts. As a typical example, Silicalite-1 supported Pt nanoparticles exhibits the highest activity, giving the 50% conversion temperature (T 50 ) and 90% conversion temperature (T 90 ) at 112 °C and 118 °C, respectively. Characterizations of these catalysts with multiple techniques show that the enhanced catalytic activities are strongly related to the zeolite Si/Al ratios of the catalysts, where an increase of zeolite Si/Al ratio is favorable for the adsorption of propene, promoting the propene oxidation. This feature might offer a good opportunity to design and prepare highly efficient heterogeneous catalysts for removal of light olefins in the future.
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ChemElectroChem
·
2019
·Vol. 6
·期 14
·3633-3643
·
IF 3.975
Dahui Fang,Hongjie Zhang,Liang He,Jiangtao Geng,Wei Song,Shucheng Sun,Zhigang Shao,Baolian Yi
Graphical The perfect ratio : Nanoporous Pt-encapsulated Ir black with an Pt/Ir mass ratio of 55/45 (Pt 55 @Ir 45 ) was synthesized by a water modified polyol process at room temperature to fabricate a bifunctional oxygen catalyst, which exhibited superior activity and durability toward ORR and OER due to the nanoporous Pt layer constructing a conductive network without hindering mass transport and protecting the inner Ir from being leached or severely oxidized. The exploitation of a bifunctional oxygen catalyst with high efficiency is crucial for a high-performance unitized regenerative fuel cell (URFC). However, the existing bifunctional oxygen catalysts still suffer from low catalytic efficiency due to sluggish oxygen electrode reactions toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, we report on a facile synthesis of nanoporous Pt-encapsulated Ir black with Pt/Ir mass ratio of 55/45 (Pt 55 @Ir 45 ) via a newly modified polyol process at room temperature with the aid of water. The resulting Pt 55 @Ir 45 catalyst demonstrated to be highly efficient and robust for both ORR and OER, relative to a mixture of commercial Pt and Ir black with Pt/Ir mass ratio of 50/50 (Pt 50 /Ir 50 ). Mass activity of Pt 55 @Ir 45 presented an 8.7- and 1.6-fold increase toward ORR and OER, respectively, compared with the Pt 50 /Ir 50 catalyst. The enhanced bifunctional performance was rationalized in terms of the maximized Pt utilization, achieved by the excellent dispersion of Pt nanoparticles, and the nanoporous Pt layer constructing a conductive network without impeding the transport of oxygen and water molecules. Our work demonstrates an effective means to encapsulate nanoporous Pt layers on Ir black for the fabrication of bifunctional oxygen catalysts.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Chao Hu,Yunong Zhou,Meifang Xiao,Gang Yu
Control of the structure and shape of platinum nanocrystals has recently attracted much attention, mostly due to their specific properties and related catalytic functionalities. However, the realization of platinum nanocrystals with controlled sizes and dominant facet types remains a significant challenge. In this study, platinum nanoparticles with controllable sizes and dominant facets are produced via a simple, organic agent-free, rapid, clean and direct chemical reduction method. The effects of initial solution pH on the sizes and dominant facets of the platinum nanoparticles are investigated and the mechanism for different sizes and facets are examined. Electrocatalytic analyses show that the catalytic activities and stabilities of the synthesized platinum nanoparticles are related to their sizes and dominant facets, and these nanoparticles display great potential as substitutes for commercial Pt/C in the effective catalysis of ethylene glycol , methanol, and ethanol electrooxidation in alkaline medium . Among the present platinum nanoparticles, the nanoparticles synthesized in pH 3 initial conditions, with small average size and (111)-dominant facets, display the best electrocatalytic activity and stability.
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JOURNAL OF POWER SOURCES
·
2018
·
IF 6.945
X.T. Li,H. Lei,C. Yang,Q.B. Zhang
Developing highly active and durable methanol electrooxidation reaction electrocatalysts for direct methanol fuel cells is crucial to achieve their practical application in future energy storage and conversion . Herein, we demonstrate that a nickel supported Pt-decorated electrode with an ultralow mass loading (1.50 μg cm −2 ) featuring Ni-Pt hybrid nanoparticles growing on self-reconstructed porous nickel frameworks (Pt/p-Ni) is synthesized via a facile electrochemical activation process . The self-supported Pt/p-Ni exhibits 3.65-fold higher activity for catalyzing the methanol electrooxidation reaction than that of commercial Pt/C with the same Pt loading under alkaline media . The activation approach results in surface rearrangement of Ni substrate to form nanoporous skeletons and highly dispersed Ni-Pt hybrid nanoparticles with a mean size of 4.34 nm grown on the nano-ligaments of the Ni porous skeletons. The porous skeletons decorated with nano-dispersion of Pt significantly increase the surface active sites and, therefore, yield a superior catalytic activity . Experiments coupled with density-functional theory calculations suggest the existence of a strong electronic interaction at the superface of the Pt/p-Ni, which leads to efficiently weaken the adsorption of CO on the catalyst surface and alleviate the CO ads poisoning of the active sites, resulting in remarkably enhanced methanol electrooxidation activity and durability.
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