Synthesis of Ag–decorated vertical graphene nanosheets and their electrocatalytic efficiencies

2022 ◽  
Author(s):  
Jiali CHEN ◽  
Peiyu Ji ◽  
Maoyang Li ◽  
Tianyuan Huang ◽  
Lanjian Zhuge ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ag Nanoparticles ◽  
Active Sites ◽  
Graphene Nanosheets ◽  
Chemical Vapor ◽  
Reduction Reaction ◽  
Aqueous System ◽  
Wall Structure ◽  
Plasma Chemical Vapor Deposition ◽  
Helicon Wave

Abstract Herein, we report the successful preparation of Ag–decorated vertical–oriented graphene sheets (Ag/VGs) via helicon wave plasma chemical vapor deposition (HWP–CVD) and radio frequency plasma magnetron sputtering (RF–PMS). VGs were synthesized in a mixture of argon and methane (Ar/CH4) by HWP–CVD, and then the silver nanoparticles on the prepared VGs were modified using the RF-PMS system under different sputtering times and RF power levels. The morphology and structure of the Ag nanoparticles were characterized by scanning electron microscopy (SEM), and the results revealed that Ag nanoparticles were evenly dispersed on the mesoporous wall of the VGs. X-ray diffraction (XRD) results showed that the diameter of the Ag particles increased with the increase of silver loading, and the average size was between 10.49 nm and 25.9 nm, which were consistent with transmission electron microscopy (TEM) results. Ag/VGs were investigated as effective electrocatalysts for use in an alkaline aqueous system. Due to the uniquely ordered and interconnected wall structure of VGs, the area of active sites increased with the Ag loading, which made the Ag/VGs have high oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance. The double–layer capacitance (Cdl) of the Ag/VGs under different silver loadings were studied, and the results showed that highest silver content is the best (1.04 mF/cm2). The results showed that, Ag/VGs expected to be a credible electrocatalytic material.

scholarly journals Novel Graphene/In2O3 Nanocubes Preparation and Selective Electrochemical Detection for L-Lysine of Camellia nitidissima Chi

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1999
Author(s):  
Jinsheng Cheng ◽  
Sheng Zhong ◽  
Weihong Wan ◽  
Xiaoyuan Chen ◽  
Ali Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Sensor ◽  
Chiral Recognition ◽  
Graphene Nanosheets ◽  
Reduction Reaction ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Transmission Electron ◽  
Camellia Nitidissima

In this work, novel graphene/In2O3 (GR/In2O3) nanocubes were prepared via one-pot solvothermal treatment, reduction reaction, and successive annealing technology at 600 °C step by step. Interestingly, In2O3 with featured cubic morphology was observed to grow on multi-layered graphene nanosheets, forming novel GR/In2O3 nanocubes. The resulting nanocomposites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), etc. Further investigations demonstrated that a selective electrochemical sensor based on the prepared GR/In2O3 nanocubes can be achieved. By using the prepared GR/In2O3-based electrochemical sensor, the enantioselective and chem-selective performance, as well as the optimal conditions for L-Lysine detection in Camellia nitidissima Chi, were evaluated. The experimental results revealed that the GR/In2O3 nanocube-based electrochemical sensor showed good chiral recognition features for L-lysine in Camellia nitidissima Chi with a linear range of 0.23–30 μmol·L−1, together with selectivity and anti-interference properties for other different amino acids in Camellia nitidissima Chi.

A Study of the Origin of Band-A Emission in Homoepitaxial Diamond Thin Films

1999 ◽  
Vol 588 ◽  
Author(s):  
Daisuke Takeuchi ◽  
Hideyuki Watanabe ◽  
Sadanori Yamanaka ◽  
Hideyo Okushi ◽  
Koji Kajimura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Plasma Chemical Vapor Deposition ◽  
Transmission Electron ◽  
Excitonic Emission

AbstractThe band-A emission (around 2.8 eV) observed in high quality (device-grade) homoepitaxial diamond films grown by microwave-plasma chemical vapor deposition (CVD) was studied by means of scanning cathodoluminescence spectroscopy and high-resolution transmission electron microscopy. Recent progress in our study on homoepitaxial diamond films was obtained through the low CH4/H2 conditions by CVD. These showed atomically flat surfaces and the excitonic emission at room temperature, while the band-A emission (2.95 eV) decreased. Using these samples, we found that the band-A emission only appeared at unepitaxial crystallites (UC) sites, while other flat surface parts still showed the excitonic emission. High-resolution transmission electron microscopy revealed that there were grain boundaries which contained π-bonds in UC. This indicates that one of the origin of the band-A emission in diamond films is attributed to π bonds of grain boundaries.

scholarly journals The Field Emission Properties of Graphene Aggregates Films Deposited on Fe-Cr-Ni alloy Substrates

2010 ◽  
Vol 2010 ◽  
pp. 1-4 ◽  
Author(s):  
Zhanling Lu ◽  
Wanjie Wang ◽  
Xiaotian Ma ◽  
Ning Yao ◽  
Lan Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
Plasma Chemical ◽  
Raman Scattering Spectroscopy ◽  
Emission Properties ◽  
Plasma Chemical Vapor Deposition ◽  
Field Emission Properties ◽  
Ni Alloy

The graphene aggregates films were fabricated directly on Fe-Cr-Ni alloy substrates by microwave plasma chemical vapor deposition system (MPCVD). The source gas was a mixture of and with flow rates of 100 sccm and 12 sccm, respectively. The micro- and nanostructures of the samples were characterized by Raman scattering spectroscopy, field emission scanning electron microscopy (SEM), and transparent electron microscopy (TEM). The field emission properties of the films were measured using a diode structure in a vacuum chamber. The turn-on field was about 1.0 V/m. The current density of 2.1 mA/ at electric field of 2.4 V/m was obtained.

Nitrogen-Doped Carbon Nanotubes and Graphene Nanohybrid for Oxygen Reduction Reaction in Acidic, Alkaline and Neutral Solutions

2015 ◽  
Vol 30 ◽  
pp. 50-58 ◽  
Author(s):  
Ji Yue Liu ◽  
Zan Wang ◽  
Jing Yan Chen ◽  
Xin Wang
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Chemical Vapor ◽  
Electrochemical Measurement ◽  
Reduction Reaction ◽  
Neutral Medium ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon nanotubes (N-CNTs) have beenprepared on FeNi catalyst by plasma-enhanced chemical vapor deposition in amixture of N2, O2, and CH4. On the opened topof CNT, multi-layer graphene grown self-assembly was observed by transmissionelectron microscopy and high resolution transmission electron microscopy. Thenanohybrid film analyzed by scanning electron microscopy exhibited a porous and3D morphology and pyridinic and graphitic nitrogen structure confirmed by x-rayphotoelectron spectroscopy. Electrochemical measurement indicated that the filmfacilitated about three-electron transferpathway for oxygen reduction reaction in neutral medium and two-electronreductions in both alkaline and acidic solutions.

Effect of oxygen vacancies on the surface morphology and structural properties of WO3– x nanoparticles

2019 ◽  
Vol 9 (7) ◽  
pp. 773-777 ◽  
Author(s):  
Zhiguang Yang ◽  
Chaosheng Zhu ◽  
Zhiqiang Hou ◽  
Peng Peng
Keyword(s):  
Electron Microscopy ◽  
Active Sites ◽  
Oxygen Vacancies ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
Diffraction Field ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Effect Of Oxygen

WO3 is an essential material for energy storage and catalytical technology, the oxygen vacancies level will play an essential role in its potential application. In this paper, porous tungsten oxide (WO3–x) with various oxygen contents was quickly fabricated by a microwave plasma-enhanced chemical vapor deposition method. A detailed characterization of structure and morphology features with the plasma handling process was recorded by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy, respectively. The etching mechanism of porous WO3–x under H2 plasma was discussed based on the systemically characterization. These results will help us to design the active sites or structure in the metal oxide materials.

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