高浓度氮掺杂多孔石墨烯的可控制备及类酶催化性质

Controllable Preparation of High Concentration Nitrogen-Doped Porous Graphene toward Enzyme-like Catalytic Properties

通过改进的Hummer法合成氧化石墨烯(GO),然后以氨水为氮源,经过一步水热法温和地制备了具有丰富纳米孔的氮掺杂还原氧化石墨烯(N-RGO)筛网状片层。N-RGO显示出高效的类酶催化活性,可以催化氧化多种有机化合物发生显色反应,如3,3',5,5'-四甲基联苯胺(TMB)、邻苯二胺(OPD)、2,2'-叠氮基-二(3-乙基苯并噻唑啉磺酸)(ABTS)等。利用透射电子显微镜(TEM)、Raman光谱和X射线光电子能谱(XPS)对其进行系统表征。通过平行试验证明N-RGO催化氧化TMB是氧气参与的高效4电子转移反应过程。催化性能测试表明N-RGO相对辣根过氧化物酶(HPR)表现出了更强的耐受性,在较宽范围内(温度25~85℃,pH值4~7,NaCl浓度0~100 mmol·L^-1)均具有类酶催化活性。通过Michaelis-Menten模型的拟合可知,当GO浓度为5 mg·mL^-1时合成的N-RGO表现出较低的米氏常数(Km≈0.2 mmol·L^-1)和较高的反应速率(vmax≈0.07μmol·L^-1)。

Graphene oxide(GO)was synthesized by modified Hummer's method.Nitrogen-doped reduced graphene oxide(N-RGO)meshes with enriched nano-pores were prepared through one-step and mild hydrothermal reaction,by using ammonium hydroxide as the nitrogen-dopant source.The N-RGO exhibited high enzyme-like catalytic activity and could catalyze the organic compounds to induce chromogenic reaction,such as 3,3',5,5'-tetramethylbenzidine(TMB),o-phenylenediamine(OPD)and 2,2'-azino-di(3-ethylbenzothiazoline sulfonic acid)(ABTS),etc.The N-RGO meshes were systematically characterized by transmission electron microscope(TEM),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS).Control experiments revealed that the catalytic oxidation of TMB by NRGO was processed by an effective 4-electron transfer reaction involving oxygen.Catalytic performance indicated that the N-RGO meshes had stronger tolerance than horseradish peroxidase(HPR),which maintained catalytic activity in a wider range(temperature of 25~85℃,pH value of 4~7,and NaCl concentration of 0~100 mmol·L^-1).From the fitting calculation by using the Michaelis-Menten model,the N-RGO meshes generated in optimized GO concentration of 5 mg·mL^-1 possessed the lowest Michaelis constant(Km≈0.2 mmol·L^-1)and the highest reaction velocity(vmax≈0.07μmol·L^-1).