Synthesis Of Hybrid Nanocomposites Of ZIF-8 With Few-layer Black Phosphorus For Photo Degradation Of Methylene Blue

MOFs(Metal-Organic Frameworks)as an emerging type of porous crystalline materials,due to their compositional,structural and chemical versatility,have been received increasing attention in recent years.Meanwhile,the two-dimensional materials(Two-Dimensional Materials)fundamental study and technological development has also made great progress,which exhibit a number of unique and attractive properties in a wide range of applications.Recently,the intelligent combination of the aforementioned two types of functional materials has led to the improved performance in gas storage,gas separation and catalysis.Black phosphorus(BP)as a new type of two-dimensional materials,with thickness-dependent bandgap and impressive carrier mobility,has been widely applied in optoelectronic devices,however,the research of BP composites is still relatively scarce.Zeolitic imidazolate framework-8(ZIF-8)as a kind of MOFs materials has exceptional thermal and chemical stability,widely applied in separation,storage and photocatalysis,and can be prepared at room temperature and does not require heating,so in the process of hybrid with black phosphorus(BP)is not will cause damage to the black phosphorus.Therefore,the preparation of ZIF-8/BP nanocomposites and its photocatalysis application are studied in this paper.The main research contents are as follows:1.Preparation of bulk black phosphorus(BP)material and a few layers of black phosphorus(FL-BP):In this paper,bulk black phosphorus was prepared through a facile low-pressurs transport route by using red phosphorus as raw material.(FL-BP)with a uniform size and a thickness of about 5 nm were successfully prepared.The degradation of FL-BP in water was briefly discussed.2.Preparation and growth mechanism of ZIF-8/BP nanocomposites:Unlike the graphene oxide(GO),the surface of FL-BP has no oxygen-containing functional groups and is difficult to coordinate with metal ions.Therefore,(PVP)was used to modify FL-BP,so that the metal ions could coordinate with the carbonyl group(C=O)on PVP,and ZIF-8 was successfully in situ grown on the surface of FL-BP to prepare ZIF-8/BP nanocomposites.Meanwhile,the effects of different growth time,PVP concentration and zinc ion concentration on ZIF-8/BP were studied,and the optimum conditions for preparation of ZIF-8/BP were determined.A simple mechanism analysis of the coordination of zinc ions with C=O was carried out.It was found that zinc ions did form a coordination effect with C=O,which is the key to the preparation of ZIF-8/BP.3.The photocatalytic application of ZIF-8/BP and its photocatalytic mechanism:ZIF-8/BP was applied to photocatalytic degradation of MB,and its pseudo-first order kinetic constant was k--4.49 ×10-2 min-1,is 3 times the ZIF-8 alone.The photocatalytic efficiency of ZIF-8/BP prepared under different growth times,PVP concentration and zinc ion concentration was compared.The concentration of hydroxyl radical(·OH)produced by ZIF-8/BP and ZIF-8 was compared by the method of fluorescence.The mechanism of ZEF-8/BP photocatalysis is studied and it is found that FL-BP can effectively transfer the electrons produced by ZIF-8,which inhibits the recombination of electrons and hole pairs(e-—h+)on ZIF-8,Thereby improving the catalytic efficiency.