Theoretical study on the catalytic properties of single-atom catalyst stabilised on silicon-doped graphene sheets

ABSTRACT

The stable configurations, electronic structures and catalytic activities of single-atom metal catalyst anchored silicon-doped graphene sheets (3Si-graphene-M, M?=?Ni and Pd) are investigated by using density functional theory calculations. Firstly, the adsorption stability and electronic property of different gas reactants (O₂, CO, 2CO, CO/O₂) on 3Si-graphene-M substrates are comparably analysed. It is found that the coadsorption of O₂/CO or 2CO molecules is more stable than that of the isolated O₂ or CO molecule. Meanwhile, the adsorbed species on 3Si-graphene-Ni sheet are more stable than those on the 3Si-graphene-Pd sheet. Secondly, the possible CO oxidation reactions on the 3Si-graphene-M are investigated through Eley–Rideal (ER), Langmuir–Hinshelwood (LH) and new termolecular Eley–Rideal (TER) mechanisms. Compared with the LH and TER mechanisms, the interaction between 2CO and O₂ molecules (O₂?+?CO → CO₃, CO₃?+?CO → 2CO₂) through ER reactions (< 0.2?eV) are an energetically more favourable. These results provide important reference for understanding the catalytic mechanism for CO oxidation on graphene-based catalyst.     

Enhancing hydrogen evolution of MoS2 basal planes by combining single-boron catalyst and compressive strain

MoS₂ is a promising candidate for hydrogen evolution reaction (HER), while its active sites are mainly distributed on the edge sites rather than the basal plane sites. Herein, a strategy to overcome the inertness of the MoS₂ basal surface and achieve high HER activity by combining single-boron catalyst and compressive strain was reported through density functional theory (DFT) computations. The ab initio molecular dynamics (AIMD) simulation on B@MoS₂ suggests high thermodynamic and kinetic stability. We found that the rather strong adsorption of hydrogen by B@MoS₂ can be alleviated by stress engineering. The optimal stress of −7% can achieve a nearly zero value of ΔG_H (~ −0.084 eV), which is close to that of the ideal Pt–SACs for HER. The novel HER activity is attributed to (i) the B– doping brings the active site to the basal plane of MoS₂ and reduces the band-gap, thereby increasing the conductivity; (ii) the compressive stress regulates the number of charge transfer between (H)–(B)–(MoS₂), weakening the adsorption energy of hydrogen on B@MoS₂. Moreover, we constructed a SiN/B@MoS₂ heterojunction, which introduces an 8.6% compressive stress for B@MoS₂ and yields an ideal ΔGH. This work provides an effective means to achieve high intrinsic HER activity for MoS₂.     

SO_4~(2-)_ZrO_2-TiO_2催化剂的制备及性能

本文用三种不同的方法制备了SO_4~(2-)/ZrO_(2-)TiO_2催化剂,并用Caro Eala自动吸附仪、PE683型红外光谱仪及LCT-2型高温差热天平仪分别有选择地测定了催化剂比表面及催化剂表面硫酸根的红外吸收光谱、脱附量、脱附温度,还测定了对酯化反应的催化性能。同时,讨论了制备条件和方式对催化剂性能的影响。     

二甲苯在TFJF型催化剂上深度氧化动力学的研究

在193-225 iC温度范围内，在轴向取样的管式积分反应器中研究了二甲苯在TFJF型催化剂上深度氧化的宏观动力学，在试验条件下，该反应的速度方程为:     

液相合成γ—丁内酯新型催化剂

液相合成γ┐丁内酯新型催化剂林衍华＊骆有寿（浙江大学二次资源化工国家专业实验室杭州３１００２７）关键词γ－丁内酯，１，４－丁二醇，Ｃｕ－Ｚｎ－Ｏ催化剂，绿铜锌矿１９９６－１２－０４收稿，１９９７－０６－０６修回γ－丁内酯是一种精细化学品，用作高沸点、...     

Bioglycerol-Based Sulfonic Acid-Functionalized Carbon Catalyst as an Efficient and Reusable Catalyst for One-Pot Synthesis of 3- Substituted-2H-1,4-Benzothiazines

Abstract

A simple and efficient synthetic protocol has been developed for the synthesis of 3-substituted-2H-1,4-benzothiazines by using bioglycerol-based sulfonic acid-functionalized carbon catalyst, devoid of corrosive acidic and basic reagents. The developed method has the advantages of good to excellent yields, short reaction times, operational simplicity, and a recyclable catalyst.     

Chemoselective acetylation of amines and thiols using monodispersed Ni-nanoparticles

Abstract

We report here a method by which Ni-nanoparticles can be used efficiently to catalyze the acetylation of a variety of amines and thiols under ambient conditions at room temperature. However in a competitive reaction, the thiol was acetylated selectively while the amine remained almost unaffected. The demonstrated chemoselectivity could have multiple potential synthetic applications. Some of the major advantages of this method are high yields, selectivity, short reaction times (<40 min), ease of operation, and compatibility with other protecting groups. Additionally, the process reported is environmentally benign.