scholarly journals Novel 2D CaCl crystals with metallicity, room-temperature ferromagnetism, heterojunction, piezoelectricity-like property, and monovalent calcium ions

2020 ◽  
Author(s):  
Lei Zhang ◽  
Guosheng Shi ◽  
Bingquan Peng ◽  
Pengfei Gao ◽  
Liang Chen ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Calcium Ions ◽  
High Performance ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Atomic Scale ◽  
Ambient Conditions ◽  
Magnetic Devices ◽  
Reduced Graphene ◽  
Potential Applications

Abstract Under ambient conditions, the only known valence state of calcium ions is + 2, and the corresponding crystals with calcium ions are insulating and nonferromagnetic. Here, using cryo-electron microscopy, we report the direct observation of two-dimensional (2D) CaCl crystals on reduced graphene oxide (rGO) membranes, in which the calcium ions are only monovalent (i.e. +1). Remarkably, metallic rather than insulating properties are displayed by those CaCl crystals. More interestingly, room-temperature ferromagnetism, graphene–CaCl heterojunction, coexistence of piezoelectricity-like property and metallicity, as well as the distinct hydrogen storage and release capability of the CaCl crystals in rGO membranes are experimentally demonstrated. We note that such CaCl crystals are obtained by simply incubating rGO membranes in salt solutions below the saturated concentration, under ambient conditions. Theoretical studies suggest that the formation of those abnormal crystals is attributed to the strong cation–π interactions of the Ca cations with the aromatic rings in the graphene surfaces. Those findings show the realistically potential applications of such abnormal CaCl material with unusual electronic properties in designing novel transistors and magnetic devices, hydrogen storage, catalyzer, high-performance conducting electrodes and sensors, with a size down to atomic scale.

Ordered Intermetallic Nanoparticles with High Catalytic Activity Prepared by an Electrochemically Induced Phase Transformation

2019 ◽  
Author(s):  
Du Sun ◽  
yunfei wang ◽  
Kenneth Livi ◽  
chuhong wang ◽  
ruichun luo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Diffusion Mechanism ◽  
Reduction Reaction ◽  
Atomic Scale ◽  
High Catalytic Activity ◽  
Ambient Conditions ◽  
Magnetic Devices ◽  
Disordered Alloys ◽  
Ordered Intermetallic ◽  
Intermetallic Nanoparticles

<div> <p>The synthesis of alloys with long range atomic scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in materials development. We report a process for converting colloidally synthesized ordered intermetallic PdBi<sub>2</sub> to ordered intermetallic Pd<sub>3</sub>Bi nanoparticles under ambient conditions by an electrochemically induced phase transition. The low melting point of PdBi<sub>2</sub> corresponds to low vacancy formation energies which enables the facile removal of the Bi from the surface, while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd<sub>3</sub>Bi exhibits 11x and 3.5x higher mass activty and high methanol tolerance for the oxygen reduction reaction compared to Pt/C and Pd/C, respectively,which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble metal rich ordered intermetallic phases with high catalytic activity, and sets forth guidelines for the design of ordered intermetallic compounds under ambient conditions.</p> </div>

scholarly journals Foldable and washable textile-based OLEDs with a multi-functional near-room-temperature encapsulation layer for smart e-textiles

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
So Yeong Jeong ◽  
Hye Rin Shim ◽  
Yunha Na ◽  
Ki Suk Kang ◽  
Yongmin Jeon ◽  
...  
Keyword(s):  
Room Temperature ◽  
Wearable Electronics ◽  
Ambient Conditions ◽  
Light Emitting ◽  
Stable Operating ◽  
Mechanical Durability ◽  
Potential Applications ◽  
Wearable Electronic ◽  
Data Signal ◽  
Wearable Electronic Devices

AbstractWearable electronic devices are being developed because of their wide potential applications and user convenience. Among them, wearable organic light emitting diodes (OLEDs) play an important role in visualizing the data signal processed in wearable electronics to humans. In this study, textile-based OLEDs were fabricated and their practical utility was demonstrated. The textile-based OLEDs exhibited a stable operating lifetime under ambient conditions, enough mechanical durability to endure the deformation by the movement of humans, and washability for maintaining its optoelectronic properties even in water condition such as rain, sweat, or washing. In this study, the main technology used to realize this textile-based OLED was multi-functional near-room-temperature encapsulation. The outstanding impermeability of TiO2 film deposited at near-room-temperature was demonstrated. The internal residual stress in the encapsulation layer was controlled, and the device was capped by highly cross-linked hydrophobic polymer film, providing a highly impermeable, mechanically flexible, and waterproof encapsulation.

scholarly journals Vanadium doped few-layer ultrathin MoS2 nanosheets on reduced graphene oxide for high-performance hydrogen evolution reaction

RSC Advances ◽  
2019 ◽  
Vol 9 (39) ◽  
pp. 22232-22239 ◽  
Author(s):  
Ashwani Kumar Singh ◽  
Jagdees Prasad ◽  
Uday Pratap Azad ◽  
Ashish Kumar Singh ◽  
Rajiv Prakash ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Solvothermal Synthesis ◽  
High Performance ◽  
Room Temperature ◽  
Mos2 Nanosheets ◽  
Reduced Graphene ◽  
Ultrathin Mos2 Nanosheets

In this paper, we demonstrate a facile solvothermal synthesis of a vanadium(v) doped MoS2-rGO nanocomposites for highly efficient electrochemical hydrogen evolution reaction (HER) at room temperature.

Room Temperature Ferromagnetism and Band Gap Engineering in Mg Doped ZnO RF/DC Sputtered Films

2013 ◽  
Vol 1577 ◽  
Author(s):  
Sreekanth K. Mahadeva ◽  
Zhi-Yong Quan ◽  
Jin-Cheng Fan ◽  
Hasan B. Albargi ◽  
Gillian A Gehring ◽  
...  
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Ambient Conditions ◽  
Zno Film ◽  
Band Gap Engineering ◽  
Sputtered Films ◽  
Doped Zno ◽  
Mg Doped ◽  
Comprehensive Study

ABSTRACTMg doped ZnO thin films were prepared by DC/RF magnetron co-sputtering in (Ar+O2) ambient conditions using metallic Mg and Zn targets. We present a comprehensive study of the effects of film thickness on the structural, optical and magnetic properties. Room temperature ferromagnetism was observed in the films and the saturation magnetization (MS) increases at first as the film’s thickness increases and then decreases. The MS value as high as ∼15.76 emu/cm3 was achieved for the Mg-doped ZnO film of thickness 120 nm. The optical band gap of the films determined to be in the range 3.42 to 3.52 eV.

scholarly journals N-doped reduced graphene oxide for room-temperature NO gas sensors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu-Sung Chang ◽  
Feng-Kuan Chen ◽  
Du-Cheng Tsai ◽  
Bing-Hau Kuo ◽  
Fuh-Sheng Shieu
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Room Temperature ◽  
Gas Sensing ◽  
Ambient Conditions ◽  
Gas Sensitivity ◽  
Nitrogen Doped ◽  
Low Concentrations ◽  
Reduced Graphene ◽  
P Type

AbstractIn this study, we use nitrogen-doped to improving the gas-sensing properties of reduced graphene oxide. Graphene oxide was prepared according to a modified Hummers’ method and then nitrogen-doped reduced graphene oxide (N-rGO) was synthesized by a hydrothermal method using graphene oxide and NH4OH as precursors. The rGO is flat and smooth with a sheet-like morphology while the N-rGO exhibits folded morphology. This type of folding of the surface morphology can increase the gas sensitivity. The N-rGO and the rGO sensors showed n-type and p-type semiconducting behaviors in ambient conditions, respectively, and were responsive to low concentrations of NO gases (< 1000 ppb) at room temperature. The gas-sensing results showed that the N-rGO sensors could detect NO gas at concentrations as low as 400 ppb. The sensitivity of the N-rGO sensor to 1000 ppb NO (1.7) is much better than that of the rGO sensor (0.012). Compared with pure rGO, N-rGO exhibited a higher sensitivity and excellent reproducibility.

Electrospraying preparation of metal germanate nanospheres for high-performance lithium-ion batteries and room-temperature gas sensors

Nanoscale ◽  
2019 ◽  
Vol 11 (25) ◽  
pp. 12116-12123 ◽  
Author(s):  
Rui Li ◽  
Renmu Zhang ◽  
Zheng Lou ◽  
Tingting Huang ◽  
Kai Jiang ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Gas Sensors ◽  
High Performance ◽  
Large Scale ◽  
Room Temperature ◽  
Lithium Ion ◽  
Ammonia Gas ◽  
Potential Applications ◽  
Ammonia Gas Sensors

Metal germanate nanospheres including Ca2Ge7O16, Zn2GeO4 and SrGe4O9 were prepared by a facile and large-scale electrospraying process. They have potential applications in lithium-ion batteries and room temperature ammonia gas sensors.

Room-temperature high-performance acetone gas sensor based on hydrothermal synthesized SnO2-reduced graphene oxide hybrid composite

RSC Advances ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 3016-3022 ◽  
Author(s):  
Dongzhi Zhang ◽  
Aiming Liu ◽  
Hongyan Chang ◽  
Bokai Xia
Keyword(s):  
Graphene Oxide ◽  
Composite Film ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Hybrid Composite ◽  
High Performance ◽  
Room Temperature ◽  
Tin Dioxide ◽  
Reduced Graphene

In this paper, we demonstrated a room-temperature acetone gas sensor based on a tin dioxide (SnO2)-reduced graphene oxide (RGO) hybrid composite film.

Reduced Graphene Oxide for Room Temperature Hydrogen Storage Application

2015 ◽  
Vol 1086 ◽  
pp. 91-95 ◽  
Author(s):  
A. Venkatesan ◽  
Raj Nanalal Patel ◽  
E.S. Kannan
Keyword(s):  
Graphene Oxide ◽  
Electric Field ◽  
Hydrogen Storage ◽  
Reduced Graphene Oxide ◽  
Room Temperature ◽  
Structural Defects ◽  
Back Gate ◽  
Hot Air ◽  
Reduced Graphene ◽  
P Type

Graphene oxide (GO) is extracted from graphite oxide synthesized using modified Hummers method. The extracted GO solution is then drop casted onto a p type silicon substrate and dried in hot air oven. The dried solution is annealed at a temperature of about 200 degree Celsius for about one hour to obtain thermally reduced graphene oxide (RGO). Such thermally synthesized RGO usually have a lot of structural defects which can act as a binding site for hydrogen. The binding efficiency of hydrogen to defect centers can be increased by applying electric field to RGO as it changes the carrier concentration (doping) on the surface. This induces more polarization in the hydrogen molecule resulting in strong binding force, thereby increasing its hydrogen storage efficiency. In our experiment we have demonstrated room temperature electric field doping in RGO films by modulating the channel current by changing the back gate voltage which is a precursor for employing RGO in hydrogen storage applications.KeywordsGraphene oxide, Reduced graphene oxide, Field effect, Hydrogen storage, and Defects

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