Search query: graphene/semiconductor composite nanocatalysts

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abstract: Heterogeneous catalysts with precise surface and interface structures are of great interest to decipher the structure property relationships and maintain remarkable stability while achieving high activity. Here, we report the design and fabrication of the new sandwich composites ZIF 8@Au25@ZIF 67[tkn] and ZIF 8@Au25@ZIF 8[tkn] [tkn thickness of shell] by coordination assisted self assembly with well defined structures and interfaces. The composites ZIF 8@Au25@ZIF 67 efficiently catalyzed both 4 nitrophenol reduction and of terminal alkyne carboxylation with CO2 un der ambient conditions with remarkably improved activity and stability, compared to the simple components Au25/ZIF 8 and Au25@ZIF 8, highlighting the highly useful function of the ultrathin shell. In addition, the performances of these compo site sandwich catalysts are conveniently regulated by the shell thickness. This concept and achievements should open a new avenue to the targeted design of well defined nanocatalysts with enhanced activities and stabilities for challenging reac tions.
author_names: Yapei Yun

Hongting Sheng

Kang Bao

Li Xu

Yuanyuan Zhang

Didier Astruc

Manzhou Zhu
title: Design and Remarkable Efficiency of the Robust Sandwich Cluster Composite Nanocatalysts ZIF 8@Au25@ZIF 67.
venue: Journal of the American Chemical Society
year: 2020

abstract: Abstract In recent years, catalytic hydrolysis of sodium borohydride is considered to be a promising approach for hydrogen generation towards fuel cell devices, and highly efficient and noble metal free catalysts have attracted increasing attention. In our present work, Co3O4 nanocubes are synthesized by solvothermal method, and then vapor phase phosphorization treatment is carried out for the preparation of novel Co O P composite nanocatalysts composed of multiple active centers including Co, CoO, and Co2P. For catalyst characterization, field emission scanning electron microscopy (FE SEM) transmission electron microscopy (TEM) energy dispersive spectrometry (EDS) X ray diffraction (XRD) and X ray photoelectric spectroscopy (XPS) are conducted. Optimal conditions for catalyst preparation and application were investigated in detail. At room temperature (25 degC) maximum hydrogen generation rate (HGR) is measured to be 4.85 L min 1 g 1 using a 4 wt% NaBH4 8 wt% NaOH solution, which is much higher than that of conventional catalysts with single component reported in literature. It is found that HGR remarkably increases with the increasing of reaction temperature, and apparent activation energy for catalytic hydrolysis of NaBH4 is calculated to be 63 kJ mol 1. After reusing for five times, the Co O P composite nanocatalysts still retains 78% of the initial activity.
author_names: Lei Wei

Xiaolong Dong

Yumei Yang

Qianqian Shi

Yanhong Lu

Hongyan Liu

Ya-Na Yu

Meng-Han Zhang

Meng Qi

Qin-qin Wang
title: Co O P composite nanocatalysts for hydrogen generation from the hydrolysis of alkaline sodium borohydride solution
year: 2020

abstract: Abstract In this work, we developed ternary metallic cobalt cobalt nitride dicobalt phosphide composite embedded in nitrogen and phosphorus co doped carbon (Co/CoN/Co2P NPC) as bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) The as prepared Co/CoN/Co2P NPC is achieved by simultaneous annealing and phosphating of a Co N rich metal organic frameworks (MOFs) precursor. Compare with the phosphorus free Co/CoN embedded nitrogen doped carbon electrocatalyst (Co/CoN NC) the as prepared Co/CoN/Co2P NPC display superior HER and OER low overpotential of 99 mV and 272 mV at current density of 10 mA cm 2. When Co/CoN/Co2P NPC electrocatalyst is use as bifunctional catalysts in overall alkaline water splitting, it exhibit excellent behaviour with 10 mA cm 2 current at overall cell potential of 1.60 V. The excellent performance of Co/CoN/Co2P NPC electrocatalyst is attributed to the phosphating process that could further enhance synergistic effect, create stronger electronic interactions, and form efficient dual heteroatom doping to optimize the interfacial adhesion within the electrocatalyst. This present work will create more opportunities for the development of new, promising and more active sites electrocatalysts for alkaline electrolysis.
author_names: Lei Hu

Yu-wen Hu

Ran Liu

Yanchao Mao

Muhammad-Sadeeq Balogun

Yexiang Tong
title: Co based MOF derived Co/CoN/Co2P ternary composite embedded in N and P doped carbon as bifunctional nanocatalysts for efficient overall water splitting
venue: International Journal of Hydrogen Energy
year: 2019

abstract: Direct alkaline ethanol fuel cells (DAEFCs) have attracted great attention as one of the most promising portable energy systems. In this work, we report a novel and facile method to prepare PdAg/xCeO2/C hybrid nanostructured anode catalysts without reducing agents or surfactants. The microstructure and morphology of the as synthesized nanocatalysts were investigated by X ray diffraction (XRD) high resolution transmission electron microscopy (HRTEM) and X ray photon spectroscopy (XPS) techniques. Furthermore, the electrochemical performance of the resultant catalysts was studied using cyclic voltammetry (CV) and chronoamperometry (CA) measurements. Among the different compositions of PdAg/xCeO2/C catalysts, PdAg/30CeO2/C showed the highest performance for ethanol electro oxidation reaction (EOR) in the alkaline medium. Such an excellent performance for the EOR indicates that the as synthesized PdAg/30CeO2/C catalyst could be potentially used as a high performance anode catalyst in DAEFCs.
author_names: Ayong Xie

Qing Zhang

Hui He

Cheng Peng
title: Facile synthesis of PdAg nanocatalysts on CeO2/C composite supports as high performance catalysts toward alkaline ethanol electro oxidation
year: 2020

abstract: Abstract Graphene possesses many superior properties which make it an ideal matrix to support semiconductors. Recently, graphene/semiconductor composites have been applied increasingly in environmental remediation and energy production. This review provided a general overview of the latest research results of graphene/semiconductor composites nanocatalysts. Firstly, synthetic methods of graphene/semiconductor composites were summarized. The roles of graphene in promoting semiconductor photocatalytic performance including increasing the adsorption of reactants, expanding the range of light absorption and intensity, acting as a photosensitizer and electron transfer medium were then emphasized. Next, the performance and mechanisms in pollutants removal, disinfection, hydrogen evolution, CO2 reduction, selective oxidation, nitroaromatics reduction, sensing, supercapacitors and other fields were presented. Besides, the toxicity of graphene and graphene/semiconductor composites was also introduced to help understand the impact on living systems of the environment. Finally, perspectives and challenges of graphene/semiconductor composites for future development were proposed. This review gives a comprehensive and updated overview of graphene/semiconductor composites for environmental and energy applications and is expected to shed light on the further study in this exciting area.
author_names: Yu-Mei Hu

Chengyun Zhou

Han Wang

Ming Chen

Guangming Zeng

Zhifeng Liu

Wenjun Wang

Ting Wu

Binbin Shao

Qinghua Liang
title: Recent advance of graphene/semiconductor composite nanocatalysts: Synthesis, mechanism, applications and perspectives
year: 2021

abstract: Direct alcohol fuel cells (DAFCs) are widely regarded as one of the most promising among the futuristic and capable energy systems; direct liquid fuel cells (DLFCs) In this article, we discuss in detail the competency of palladium nanoparticles developed over carbon ceria composite supports (Pd/C CeO2) as efficient and durable anode catalysts for the alkaline electro oxidation of ethylene glycol (EGOR) For the first time, a systematic assessment of the EGOR performance of palladium catalysts with varying Pd ceria ratios has been reported. The scalable solid solution route reduction technique enabled the processing of Pd nanoparticles with controlled morphology, size and excellent CeO2 interaction. The structural features of the prepared catalysts were studied using X ray diffraction, electron microscopy (TEM) and X ray photon spectroscopy techniques, while the electrochemical performance of the catalysts was analyzed using cyclic voltammetry and chronoamperometry. During alkaline EGOR, the Pd/C CeO2 catalysts showed an enhanced current density (as high as 68.5 mA cm 2) more negative onset potential, excellent mass activity (4.6 A mg 1Pd) and exceptional durability compared to Pd/C. The enhanced alkaline EGOR kinetics of the Pd/C CeO2 catalysts is well attributed to the promotion effect of CeO2 on Pd by creating more Pd OHads and also improved tolerance to poisoning species on the Pd surface. Further, the enhanced ECSA of Pd/C CeO2 has also aided the excellent EGOR activity in alkaline medium. The validated enhanced oxidation ability of these Pd/C CeO2 catalysts for the anodic oxidation of other low molecular weight alcohol fuels including methanol and ethanol showcased their application potential toward DMFCs and DEFCs.
author_names: Sasidharan Sankar

Naoto Watanabe

Gopinathan M Anilkumar

Balagopal N Nair

Sailaja G Sivakamiammal

Takanori Tamaki

Takeo Yamaguchi
title: Electro oxidation competency of palladium nanocatalysts over ceria carbon composite supports during alkaline ethylene glycol oxidation
year: 2019

abstract: This Review article provides a report on progress in the synthesis, properties and catalytic applications of noble metal based composite nanomaterials. We begin with a brief discussion on the categories of various composite materials. We then present some important colloidal synthetic approaches to the composite nanostructures; here, major attention has been paid to bimetallic nanoparticles. We also introduce some important physiochemical properties that are beneficial from composite nanomaterials. Finally, we highlight the catalytic applications of such composite nanoparticles and conclude with remarks on prospective future directions.
author_names: Yuanfang Xu

Liquan Chen

Xuchun Wang

Wei Yao

Qiao Zhang
title: Recent advances in noble metal based composite nanocatalysts: colloidal synthesis, properties, and catalytic applications.
venue: Nanoscale
year: 2015

abstract: Abstract The multi walled carbon nanotubes (MWNTs) are introduced as reductants to prepare bimetallic PtNix composite nanocatalysts via a hydrothermal reaction for the investigation of ethanol oxidation reaction (EOR) The crystal structure and elemental analysis of PtNix/MWNTs nanocatalysts are characterized by X ray diffraction (XRD) and energy dispersive X ray spectroscopy (EDS) respectively. The morphologies of these nanocatalysts are observed by transmission electron microscopy (TEM) and scanning electron microscope (SEM) The results reveal that the PtNix nanocatalysts with a nanoparticle size ranging from 6 to 13 nm are immobilized on the surface of MWNTs. The electrocatalytic activities of the PtNix/MWNTs nanocatalysts for EOR in alkaline media are examined using cyclic voltammetry (CV) electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) The onset potential of EOR in the nanocatalyst of PtNi3/MWNTs is negatively shifted for about 190 mV as compared to that in the nanocatalyst of Pt/MWNTs. The current for the forward anodic peak of EOR in the PtNi3/MWNTs nanocatalyst is about 2.5 times higher than that of pure Pt/MWNTs.
author_names: Ke-qiang Ding

Zhao Yongbo

Likun Liu

Yanli Cao

Qingfei Wang

Hongbo Gu

Xingru Yan

Zhanhu Guo
title: Pt Ni bimetallic composite nanocatalysts prepared by using multi walled carbon nanotubes as reductants for ethanol oxidation reaction
year: 2014

abstract: Palladium is considered as an efficient anode catalyst with high catalytic activity for electrooxidation of formic acid.To further improve the catalytic activity and stability, alloying or surface modification with Sb is an effective way. In this work, the well dispersed carbon supported Pd Sb composite nanocatalysts(Pd Sb/C) were synthesized by traditional impregnation reduction method with trisodium citrate as the complexing agent, sodium borohydride as the reducing agent. The morphologies of Pd Sb/C and the effects of molar ratio of Pd to Sb on the electrocatalytic properties of Pd Sb/C for HCOOH electrooxidation were studied.The XRD and XPS analyses on the as prepared Pd Sb/C catalyst revealed that Sb(0) was presented on the Pd surface, and the immature alloying of Pd with Sb was achieved. Cyclic voltammetryic and chronoamperometric studies indicated a volcano shaped relationship between Sb content and electrocatalytic activity with an optimum molar ratio of Pd:Sb=20:1. Compared with the commercial Pd/C catalyst, the Pd Sb/C(20:1) presented the highest electrocatalytic activity and best stability. This enhancement may be attributed to the electronic effect and bi functional effect induced by addition of Sb onto Pd surface, resulting in a weaker adsorption and accelerated oxidative removal of CO poison formed during HCOOH electrooxidation.
author_names: Wang Long-lon
title: Preparation and Characterization of Carbon Supported Pd Sb Composite Nanocatalysts for Formic Acid Electrooxidation
year: 2015

abstract: Supported gold catalysts have attracted intensive interest due to their unique catalytic properties. The easy sintering of gold particles, however, is still the major obstacle to the practical application of gold catalysts. Herein, a highly active and sintering resistant TiO2 hydroxyapatite (HAP, Ca10(PO4)6(OH)2) composite supported gold catalyst was prepared by a deposition precipitation method. TEM results manifested TiO2 HAP had smaller gold nanoparticles than TiO2 and HAP. Patterns of TG DTG revealed that the presence of HAP inhibited the phase transformation from anatase to rutile. Based on UV Vis and BET studies, HAP prevented the formation of large TiO2 agglomerates, leading to higher dispersion of TiO2 nanoparticles in TiO2 HAP composites. Au/TiO2 HAP had the higher activity and sintering resistance compared with Au/TiO2 and Au/HAP for CO oxidation. TiO2 HAP and Au/TiO2 HAP exhibited the best photocatalytic activity among supports and gold nanocatalysts, respectively. Gold nanoparticles could further improve the photocatalytic performance. It was likely that the synergistic interaction among gold nanoparticles, TiO2 and HAP was responsible for the high activity and sintering resistance of Au/TiO2 HAP.Graphical Abstract
author_names: Jiuli Guo

Feng Dong

Siyuan Zhong

Baolin Zhu

Weiping Huang

Shoumin Zhang
title: TiO2 Hydroxyapatite Composite as a New Support of Highly Active and Sintering Resistant Gold Nanocatalysts for Catalytic Oxidation of CO and Photocatalytic Degradation of Methylene Blue
venue: Catalysis Letters
year: 2017