scholarly journals Facile Direct Seed-Mediated Growth of AuPt Bimetallic Shell on the Surface of Pd Nanocubes and Application for Direct H2O2 Synthesis

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 650 ◽  
Author(s):  
Geun-Ho Han ◽  
Ki Yoon Kim ◽  
Hyunji Nam ◽  
Hyeonjin Kim ◽  
Jihwan Yoon ◽  
...  

The selective enhancement of catalytic activity is a challenging task, as catalyst modification is generally accompanied by both desirable and undesirable properties. For example, in the case of the direct synthesis of hydrogen peroxide, Pt on Pd improves hydrogen conversion, but lowers hydrogen peroxide selectivity, whereas Au on Pd enhances hydrogen peroxide selectivity but decreases hydrogen conversion. Toward an ideal catalytic property, the development of a catalyst that is capable of improving H-H dissociation for increasing H2 conversion, whilst suppressing O-O dissociation for high H2O2 selectivity would be highly beneficial. Pd-core AuPt-bimetallic shell nanoparticles with a nano-sized bimetallic layer composed of Au-rich or Pt-rich content with Pd cubes were readily prepared via the direct seed-mediated growth method. In the Pd-core AuPt-bimetallic shell nanoparticles, Au was predominantly located on the {100} facets of the Pd nanocubes, whereas Pt was deposited on the corners of the Pd nanocubes. The evaluation of Pd-core AuPt-bimetallic shell nanoparticles with varying Au and Pt contents revealed that Pd-core AuPt-bimetallic shell that was composed of 2.5 mol% Au and 5 mol% Pt, in relation to Pd, exhibited the highest H2O2 production rate (914 mmol H2O2 gmetal−1 h−1), due to the improvement of both H2O2 selectivity and H2 conversion.

2015 ◽  
Vol 51 (58) ◽  
pp. 11591-11594 ◽  
Author(s):  
Lidong Li ◽  
Yi Peng ◽  
Yonghai Yue ◽  
Ye Hu ◽  
Xiu Liang ◽  
...  

Novel concave gold nanocuboids bounded by 24 high-index {611} facets are synthesized using the seed-mediated growth method via an overgrowth mechanism, which exhibit excellent catalytic activities over certain reactions.


Nanoscale ◽  
2014 ◽  
Vol 6 (24) ◽  
pp. 15090-15097 ◽  
Author(s):  
Kun Qi ◽  
Qiyu Wang ◽  
Weitao Zheng ◽  
Wei Zhang ◽  
Xiaoqiang Cui

Palladium porous single-crystalline nanoflowers (PSNFs) with enriched high catalytic activity {100} facets were synthesized using a mild and controllable seed mediated growth method.


Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 556 ◽  
Author(s):  
Manuel Selinsek ◽  
Manfred Kraut ◽  
Roland Dittmeyer

In recent years, various modular micro channel reactors have been developed to overcome limitations in challenging chemical reactions. Direct synthesis of hydrogen peroxide from hydrogen and oxygen is a very interesting process in this regard. However, the complex triphasic process (gaseous reactants, reaction in liquid solvent, solid catalyst) still holds challenges regarding safety, selectivity and productivity. The membrane micro reactor system for continuous liquid phase H2O2 direct synthesis was designed to reduce safety issues by separate dosing of the gaseous reactants via a membrane into a liquid-flow channel filled with a catalyst. Productivity is increased by enhanced mass transport, attainable in micro channels and by multiple re-saturation of the liquid with the reactants over the length of the reaction channel. Lastly, selectivity is optimized by controlling the reactant distribution. The influence of crucial technical features of the design, such as micro channel geometry, were studied experimentally in relationship with varying reaction conditions such as residence time, pressure, reactant ratio and solvent flow rate. Successful continuous operation of the reactor at pressures up to 50 bars showed the feasibility of this system. During the experiments, control over the reactant ratio was found to be crucial in order to maximize product yield. Thereby, yields above 80% were achieved. The results obtained are the key elements for future development and optimization of this reactor system, which will hopefully lead to a breakthrough in decentralized H2O2 production.


2015 ◽  
Vol 51 (26) ◽  
pp. 5676-5678 ◽  
Author(s):  
Pan Yu ◽  
Tao-Tao Zhuang ◽  
Meng Sun ◽  
Liang Wu ◽  
Yi Li ◽  
...  

New kinked semiconductor–metal Au–Ag2S–ZnS and Au–Ag2S–ZnS–Au heteronanorods have been synthesized for the first time by a seed-mediated growth method and their catalytic activity has been investigated.


2013 ◽  
Vol 117 (21) ◽  
pp. 11436-11443 ◽  
Author(s):  
Walid Baaziz ◽  
Benoît P. Pichon ◽  
Christophe Lefevre ◽  
Corinne Ulhaq-Bouillet ◽  
Jean-Marc Greneche ◽  
...  

2016 ◽  
Vol 420 ◽  
pp. 88-95 ◽  
Author(s):  
Ha Eun Jeong ◽  
Seongmin Kim ◽  
Myung-gi Seo ◽  
Dae-Won Lee ◽  
Kwan-Young Lee

2021 ◽  
Author(s):  
Joseph Brehm ◽  
Richard J. Lewis ◽  
David J. Morgan ◽  
Thomas E. Davies ◽  
Graham J. Hutchings

AbstractThe direct synthesis of H2O2 from molecular H2 and O2 over AuPd catalysts, supported on TiO2 and prepared via an excess chloride co-impregnation procedure is investigated. The role of Au:Pd ratio on the catalytic activity towards H2O2 formation and its subsequent degradation is evaluated under conditions that have previously been found to be optimal for the formation of H2O2. The combination of relatively small nanoparticles, of mixed Pd-oxidation state is shown to correlate with enhanced catalytic performance. Subsequently, a detailed study of catalytic activity towards H2O2 synthesis as a function of AuPd loading was conducted, with a direct correlation between catalytic activity and metal loading observed. Graphic Abstract


Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 990 ◽  
Author(s):  
André Torres-Pinto ◽  
Maria J. Sampaio ◽  
Cláudia G. Silva ◽  
Joaquim L. Faria ◽  
Adrián M. T. Silva

Hydrogen peroxide (H2O2) is a chemical which has gained wide importance in several industrial and research fields. Its mass production is mostly performed by the anthraquinone (AQ) oxidation reaction, leading to high energy consumption and significant generation of wastes. Other methods of synthesis found in the literature include the direct synthesis from oxygen and hydrogen. However, this H2O2 production process is prone to explosion hazard or undesirable by‑product generation. With the growing demand of H2O2, the development of cleaner and economically viable processes has been under intense investigation. Heterogeneous photocatalysis for H2O2 production has appeared as a promising alternative since it requires only an optical semiconductor, water, oxygen, and ideally solar light irradiation. Moreover, employing a metal-free semiconductor minimizes possible toxicity consequences and reinforces the sustainability of the process. The most studied metal‑free catalyst employed for H2O2 production is polymeric carbon nitride (CN). Several chemical and physical modifications over CN have been investigated together with the assessment of different sacrificial agents and light sources. This review shows the recent developments on CN materials design for enhancing the synthesis of H2O2, along with the proposed mechanisms of H2O2 production. Finally, the direct in situ generation of H2O2, when dealing with the photocatalytic synthesis of added-value organic compounds and water treatment, is discussed.


2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Mai Ngọc Tuan Anh

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag\(^+\) ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods.


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