scholarly journals Dynamically Unveiling Metal‐Nitrogen Coordination during Thermal Activation to Design High‐Efficient Atomically Dispersed CoN4 Active Sites

2021 ◽  
Author(s):  
Yanghua He ◽  
Qiurong Shi ◽  
Weitao Shan ◽  
Xing Li ◽  
A. Jeremy Kropf ◽  
...  
Keyword(s):  
Active Sites ◽  
Thermal Activation ◽  
High Efficient

scholarly journals Large-area printing of ferroelectric surface and super-domains for efficient solar water splitting

2020 ◽  
Author(s):  
Yu Tian ◽  
Yaqing Wei ◽  
Minghui Pei ◽  
Rongrong Cao ◽  
Zhenao Gu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Electric Fields ◽  
Electronic Structures ◽  
Active Sites ◽  
Large Area ◽  
Solar Water Splitting ◽  
High Efficient ◽  
Catalytic Sites ◽  
Order Of Magnitude ◽  
Magnitude Increase

Abstract Surface electronic structures of the photoelectrodes determine the activity and efficiency of the photoelectrochemical water splitting, but the controls of their surface structures and interfacial chemical reactions remain challenging. Here, we use ferroelectric BiFeO3 as a model system to demonstrate an efficient and controllable water splitting reaction by large-area constructing the hydroxyls-bonded surface. The up-shift of band edge positions at this surface enables and enhances the interfacial holes and electrons transfer through the hydroxyl-active-sites, leading to simultaneously enhanced oxygen and hydrogen evolutions. Furthermore, printing of ferroelectric super-domains with microscale checkboard up/down electric fields separates the distribution of reduction/oxidation catalytic sites, enhancing the charge separation and giving rise to an order of magnitude increase of the photocurrent. This large-area printable ferroelectric surface and super-domains offer an alternative platform for controllable and high-efficient photocatalysis.

Triclinic boron nanosheets high-efficient electrocatalysts for water splitting

2021 ◽  
Author(s):  
Maoping Xu ◽  
Rui Wang ◽  
Kan Bian ◽  
Chuang Hou ◽  
Yaxing Wu ◽  
...  
Keyword(s):  
Active Sites ◽  
Theoretical Calculations ◽  
Chemical Properties ◽  
Chemical Vapor ◽  
Energy Storage And Conversion ◽  
High Efficient ◽  
Long Time ◽  
Time Cycle ◽  
Metal Properties ◽  
Physical And Chemical

Abstract Recently, two-dimensional (2D) boron nanosheets have been predicted to exhibit exceptional physical and chemical properties, which is expected to be widely used in advanced electronics, optoelectronic, energy storage and conversion devices. However, the experimental application of 2D boron nanosheets in hydrogen evolution reactiuon (HER) has not been reported. Here, we have grown ultrathin boron nanosheets on tungsten foils via chemical vapor deposition (CVD). The prepared triclinic boron nanosheets are highly crystalline, which perfectly match the structure in the previous theoretical calculations. Notably, the boron nanosheets show excellent HER performance. The Tafel slope is only 64 mV/dec-1 and the nanosheets can maintain good stability under long-time cycle in acidic solution. The improvement of performance is mainly due to the metal properties and a large number of exposed active sites on the boron nanosheets, which is confirmed by first-principle calculations.

scholarly journals Benzene Sulfonate Modified ZnCr-LDH and Its Enhanced Adsorption Properties for Anionic Dyes

2021 ◽  
Author(s):  
Jia Lin ◽  
Yude Zhang ◽  
Qian Zhang ◽  
Jinli Shang ◽  
Fuyao Deng
Keyword(s):  
Aqueous Solution ◽  
Active Sites ◽  
Adsorption Process ◽  
Adsorption Behavior ◽  
Maximum Adsorption Capacity ◽  
Benzene Sulfonate ◽  
Dye Molecules ◽  
Anionic Dyes ◽  
One Pot ◽  
High Efficient

Abstract A benzene sulfonate modified hydrotalcite (SO3-LDH) was synthesized by a facile one-pot hydrothermal technique, which can efficiently remove methyl orange (MO), Congo red (CR) and orange II (OII) from aqueous solution. After modified by benzene sulfonate, the microstructure of hydrotalcite changes obviously, from the cellular structure to the stacking structure formed by the face-face contact of hydrotalcite nanosheets, which resulted in much more exchangeable nitrate ions to remain in the interlayer space. The pre-insertion of benzene sulfonate as a pillar expanded the interlayer gallery, which facilitated the pollutant anions (MO, CR and OII) into the interlayer of LDH in the subsequent adsorption process. The maximum adsorption capacity of SO3-LDH for MO, CR and OII was 4200.8 mg/g, 1252.0 mg/g and 1670.6 mg/g respectively, which is approximately 1.86 times, 1.8 times and 2.32 times that of the pristine NO3-LDH, respectively. The removal mechanism of anionic dyes was determined as anion exchange between NO3− ions and dye molecules. The adsorption behavior for MO and OII is multilayer adsorption, while the adsorption behavior for CR is monolayer adsorption. The adsorption process mainly was controlled by the chemical bonding between the dye molecules and adsorbent active sites. The benzene sulfonate modified LDH has a great potential to be used as a high-efficient adsorbent to remove anionic dyes from aqueous solution.

scholarly journals GQD/Bi2O3 Composite for high-efficient photocatalysts

2020 ◽  
Vol 213 ◽  
pp. 02037
Author(s):  
Chengli Tang ◽  
Limei Zhang
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Graphene Quantum Dots ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Minority Carrier Diffusion Length ◽  
High Efficient ◽  
Visible Light Photocatalytic

Bismuth oxide (Bi2O3) is one of the potential visible-light photocatalytic materials, however, due to low electron mobility and short minority carrier diffusion length, the photocatalytic activity of Bi2O3 is restricted. The GQD/Bi2O3 composites were synthesized stably depositing single-crystalline graphene quantum dots (GQDs) with absorption edge at ~10nm, prepared by using a top-down method. The GQDBi2O3 heterojunctions were successfully established, the photo-generated electrons transfer from the Bi2O3 to the GQDs at the interface of the GQD-Bi2O3 heterojunctions, result in efficient electron-hole pairs separation and higher photocatalytic efficiency. The optimum visible performance is achieved at GQD content of 1.0 wt %, the RhB dye was nearly completely decoloured after 90 min of visible-light irradiation, and then decrease at higher doping levels due to the thicker GQD layer will cover the active sites of Bi2O3, thus leading to the greatly reduced catalytic activity.

Sunflower stalk–derived biochar enhanced thermal activation of persulfate for high efficient oxidation of p-nitrophenol

2019 ◽  
Vol 26 (26) ◽  
pp. 27482-27493 ◽  
Author(s):  
Peng Sun ◽  
Kaikai Zhang ◽  
Jianyu Gong ◽  
Aimal Khan ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Thermal Activation ◽  
High Efficient

scholarly journals Ni-Based Catalyst Derived from NiAl Layered Double Hydroxide for Vapor Phase Catalytic Exchange between Hydrogen and Water

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1688 ◽  
Author(s):  
Xiaoyu Hu ◽  
Peilong Li ◽  
Xin Zhang ◽  
Bin Yu ◽  
Chao Lv ◽  
...  
Keyword(s):  
Layered Double Hydroxide ◽  
Vapor Phase ◽  
Active Sites ◽  
Low Cost ◽  
Isotope Separation ◽  
Nickel Catalysts ◽  
Dissociative Chemisorption ◽  
High Efficient ◽  
Double Hydroxide ◽  
Catalytic Exchange

A high-efficient and low-cost catalyst on hydrogen isotope separation between hydrogen and water is an essential factor in industrial application for heavy water production and water detritiation. In past studies, Pt-based catalysts were developed but not practical for commercial use due to their high cost for vapor phase catalytic exchange (VPCE), while for impregnated nickel catalysts with a lower cost the problems of agglomeration and low Ni utilization existed. Therefore, to solve these problems, in-situ grown Ni-based catalysts (NiAl-LDO) derived from a layered double hydroxide (LDH) precursor were fabricated and first applied in VPCE in this work. Compared with traditional impregnated Ni-based catalysts, NiAl-LDO catalysts own a unique layered structure, homogeneous dispersed metallic phase, higher specific surface area as well as stronger metal-support interactions to prevent active metal from agglomerating. These advantages are beneficial for exposing more active sites to improve dynamic contacts between H2 and HDO in a catalyst surface and can bring excellent catalytic activity under a reaction temperature of lower than 400 °C. Additionally, we found that the dissociative chemisorption of HDO and H2 occurs not only in Ni (111) but also in NiO species where chemisorbed H(ads), D(ads), OH(ads) and OD(ads) are formed. The results highlight that both of the Ni2+ species and Ni0 species possess catalytic activities for VPCE process.

scholarly journals Increasing Silicon Concentration and Doping Heteroatom to Successfully Realize High HER Catalytic Activity in 2D Metal-Free BSin (n = 1-4) Structures: A First-Principles Study

2021 ◽  
Author(s):  
Cuimei Li ◽  
Guangtao Yu ◽  
Ying Li ◽  
wei Chen
Keyword(s):  
Catalytic Activity ◽  
First Principles ◽  
Active Sites ◽  
Low Cost ◽  
Atomic Ratio ◽  
Two Dimensional ◽  
Metal Free ◽  
Catalytic Activities ◽  
High Efficient ◽  
New Strategies

Abstract Under the DFT calculations, the graphene-like two-dimensional (2D) BSin (n = 1-4) nanostructures are stable in terms of energy, kinetics and thermal aspects, and can possess metallic conductivity, which are advantageous to their catalytic activities for hydrogen evolution reaction (HER). Our computed results reveal that they can uniformly exhibit high HER catalytic activity. With increasing the Si/B atomic ratio, higher HER activity can be achieved, due to the change from weak aromaticity to strong anti-aromaticity for the correlative BxSiy six-membered rings. Moreover, by doping P, S, Ge and C atoms with the different electronegativity, the HER activity of the studied systems can be further improved because the electron transfer induced by these dopants can effectively activates the relevant B and Si atoms. In addition, in view of more active sites, increasing the Si concentration can also generally increase the HER activity of doped systems. For all BSin systems studied, the Si-Si bridge sites or Si-sites can uniformly serve as the most active sites. This study not only represents the first application of 2D metal-free BSin in HER catalysis, but also provides new strategies for designing high-efficient and low-cost HER electrocatalysts based on Si/B or even other Si-containing materials.

Modelling of catalysts and its relation to experimental problems

1992 ◽  
Vol 341 (1661) ◽  
pp. 255-268 ◽  
Keyword(s):  
Small Molecules ◽  
Active Sites ◽  
Thermal Activation ◽  
Porous Metal ◽  
Acid Sites ◽  
Zeolite Catalysts ◽  
Before And After ◽  
Porous Metal Oxides ◽  
And Diffusion

We illustrate the role of both computer simulation and the evaluation of electronic structure in the study of solid heterogeneous catalysis by reference to recent work in this laboratory on ( a ) microporous materials (that have a spatially uniform distribution of accessible active sites) and ( b ) non-porous metal oxides. Computational methodologies may be used to model, first, the structure of the uniform catalysts both before and after thermal activation, second, the docking and diffusion of molecules in solids and on their surfaces; and, third, the reaction pathways of molecules at the active site. We highlight recent successes in modelling (i) the structures of zeolitic solids, (ii) the sorption of hydrocarbons within them, (iii) the protonation of small molecules at the Bronsted acid sites in uniform solid acid (zeolite) catalysts, and (iv) the reactions of small molecules on CeO 2 and MgO surfaces.

scholarly journals Efficient Adsorbent-Desiccant Based on Aluminium Oxide

2021 ◽  
Vol 11 (6) ◽  
pp. 2457
Author(s):  
Eugene P. Meshcheryakov ◽  
Sergey I. Reshetnikov ◽  
Mariya P. Sandu ◽  
Alexey S. Knyazev ◽  
Irina A. Kurzina
Keyword(s):  
Phase Composition ◽  
Active Sites ◽  
Thermal Activation ◽  
Aluminium Oxide ◽  
Adsorption Activity ◽  
Alkaline Metals ◽  
Heated Air ◽  
Donor And Acceptor ◽  
Texture Characteristics ◽  
Efficient Adsorbent

The review describes the main methods of obtaining hydroxides and aluminium oxides (AO) of various structures from gibbsite. The promising techniques of obtaining AO adsorbents are discussed, namely the technique of thermal activation in the mode of pneumatic transport with gibbsite by heated air (TCA Gb) and the technique of thermal activation of gibbsite in centrifugal flash reactors (CTA Gb). The main methods of improving the adsorbent properties of AO, such as the optimisation of texture characteristics and phase composition, as well as the influence of the modification of aluminium oxide adsorbents, obtained using CTA and TCA technologies with cations of alkaline metals, are considered. It is shown that the modification allows a controlled variation of the characteristics of donor and acceptor active sites on the surface of adsorbents and, thus, a substantial increase in their adsorption activity, in particular, with respect to water vapour.

Sign in / Sign up

Export Citation Format

Share Document