溶剂热合成多级ZnO微球及其光催化降解苯酚

以乙二醇为溶剂,KAc为助剂,采用溶剂热法合成多级ZnO微球。通过改变反应温度来调控ZnO微球形貌,并对合成的ZnO微球进行XRD、SEM、PL和UV-Vis DRS等表征分析。结果表明,合成的ZnO为六方纤锌矿晶体结构,由短纳米棒自组装成多级微球。在紫外-可见光照射下,ZnO表现出优异的光催化降解苯酚活性,180℃合成的ZnO样品光催化活性明显优于其他温度合成的样品。用0.1 g的ZnO降解100 mL浓度为5 mg·L~(-1)的苯酚溶液,光照150 min降解率达94.5%。多级ZnO微球光催化性能的提高可推测为较窄的禁带宽度(3.08 eV)有利于吸收光子,较小的晶粒尺寸(25.38 nm)、粗糙的表面以及中空结构有利于反应液与催化剂表面的充分接触。此外,由捕获实验证实光催化降解苯酚的机理是羟基(·OH)为主要的活性自由基,在苯酚降解过程中起主要作用。

Solvothermal synthesis of hierarchical ZnO microspheres and its photocatalytic degradation of phenol

Hierarchical ZnO microspheres were synthesized via solvothermal method using ethylene glycol as solvent and potassium acetate as assistant.The morphology of ZnO microspheres was controlled by changing reaction temperature.As-synthesized ZnO microspheres were characterized by XRD,SEM,PL and UV-Vis DRS.The result showed that the synthesized hierarchical ZnO microspheres were composed of short nanorods with wurtzite crystal structure.Under UV-Vis light irradiation,all ZnO samples exhibited excellent photocatalytic activity of phenol degradation.ZnO synthesized at 180 ℃ displayed best photocatlytic activity.In the case of using 0.1 g the ZnO sample in 100 mL 5 mg·L^-1 phenol solution,degradation conversion was 94.5% after irradiation for 150 min.The enhanced photocatalytic performance of hierarchical ZnO microspheres can be supposed to narrow band gap (3.08 eV) being beneficial for absorption of photons,small paiticle size (25.38nm),rough surface and hollow structure in favor of sufficient contact between phenol molecules and surface of the catalyst.In addition,a photocatalytic mechanism is proved by carrying out trapping experiments that ·OH is the main active radical and plays important role in the phenol degradation process.