Applied Surface Science 423 (2017) 349–353 Contents lists available at ScienceDirect Applied Surface Science jou rn al h om ep age: www.elsevier.com/locate/apsusc Short Communication Monodispersed ZIF-8 particles with enhanced performance for CO 2 adsorption and heterogeneous catalysis Yebin Guan a,b , Juanjuan Shi b , Ming Xia a , Jun Zhang a , Zhenfeng Pang a , Alessandro Marchetti a , Xiaohong Wang b,∗ , Jingsong Cai a , Xueqian Kong a,∗ a Center for Chemistry of Novel & High-Performance Materials, and Department of Chemistry, Zhejiang University, Hangzhou, 310027, PR China b Anhui Key Laboratory of Functional Coordination Compounds, School of Chemistry and Chemical Engineering, Anqing Normal University, Anqing 246011, PR China a r t i c l e i n f o Article history: Received 27 March 2017 Received in revised form 2 June 2017 Accepted 17 June 2017 Available online 19 June 2017 Keywords: ZIF-8 Monodispersed CO2 adsorption Knoevenagel condensation reaction a b s t r a c t Monodispersed zeolitic imidazolate frameworks (ZIFs) were prepared with a simple method using dimethylsulfoxide (DMSO) as solvent. This method yields ZIF-8 nanoparticles with a narrow particle size distribution of 90–110 nm and the dispersion is highly stable against agglomeration. These particles have larger nanosized porosity and enhanced CO 2 adsorption capability compared to ZIF-8 prepared with dif- ferent solvents such as methanol or N, N-dimethyl formamide. Their uniform size and surface chemistry also lead to superior performance in the Knoevenagel condensation reactions. The ZIF-8 nanoparticles possess high thermal stability up to 550 ◦ C and the preparation steps are easy for scaling up which are favorable for industrial applications. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Zeolitic imidazolate frameworks (ZIFs) are sub-family of porous metal-organic frameworks (MOFs) built of tetrahedrally- coordinated metal ions bridged by imidazolates. Among them, ZIF-8 [Zn(MeIm) 2 , MeIm = 2-methylimidazolate] has recently received considerable attention due to its unique structure and properties [1]. It features a cubic lattice (space group I4 3m) and sodalite (SOD) topology that features cavities of ∼11.6 Å in diameter and apertures of 3.4 Å [1,2]. The uniform porosity, the exceptional chemical and thermal stability of ZIF-8 render a wide range of promising applications such as gas storage/separation [3,4], chro- matographic separation [5], catalysis [6,7], chemical sensors [8], seawater desalination membrane [9], drug delivery agents [10,11], etc. ZIF-8 materials can be prepared through different methods such as solvothermal routine [1], direct mixing [12,13], ultrasound [14], self-template strategy [15], microwave [16], reverse micelles tem- plate strategy [17], etc. Meanwhile, various solvents were utilized including deionized water [18,19], methanol [12,20], ionic liquid [21], N,N-dimethyl formamide (DMF) [1]. These diverse synthetic routes lead to ZIF-8 crystals of different morphologies and dis- ∗ Corresponding authors. E-mail addresses: wangxiaohong@aqnu.edu.cn (X. Wang), kxq@zju.edu.cn (X. Kong). persity as well as various degree of agglomeration. For practical applications, ZIF-8 particles with mono-dispersity and low degree of agglomeration are generally preferred for enhancement of cat- alytic and gas storage/separations performance, and for the utility as drug delivery agents [10,11]. However, the control over disper- sity of ZIF-8 nanoparticles are difficult via current methods and often the agglomeration is severe due to the irreversible binding of surface moieties [12]. We report here a rapid and simple synthesis process that produces monodispersed ZIF-8 nanoparticles with virtually no agglomeration using dimethylsulfoxide (DMSO) as the solvent. For comparison, methanol (MeOH) and dimethylformamide (DMF) are also used as solvents in parallel. ZIF-8 particles synthesized in DMSO exhibit a narrow distribution of size between 90 and 110 nm and, more impressively, are able to endure heating up to 150 ◦ C while retaining their monodispersed nature. This kind of monodis- persed ZIF-8 sample also demonstrated favorable CO 2 adsorption capacity and enhanced catalytic performance for the Knoevenagel reaction. 2. Experimental 2.1. Synthesis All reagents were commercially supplied from Shanghai Aladdin Bio-Chem Technology Co., Ltd. with analytically grade and used without further purification. Typically, 0.893 g (3.0 mmol) of http://dx.doi.org/10.1016/j.apsusc.2017.06.183 0169-4332/© 2017 Elsevier B.V. All rights reserved.