石墨烯基柔性衬底铬掺杂氧化锌的生长及催化性能研究

Growth and catalytic performance of chromium-doped zinc oxide on graphene-based flexible substrates

采用低温水热法,在石墨烯涂覆的聚对苯二甲酸乙二醇酯(PET-GR)柔性衬底上制备了不同浓度Cr掺杂的氧化锌纳米复合材料(Cr-ZnO/PET-GR)。通过X射线衍射仪(XRD)、场发射扫描电镜(FE-SEM)和X射线光电子能谱(XPS)对氧化锌的晶体结构、微观形貌及表面化学状态进行了表征,采用电化学阻抗(EIS)、光致发光光谱(PL光谱)研究了氧化锌的光、电性能,并计算了Cr^(3+)、Cr^(2+)掺杂前后的分子最高占据轨道(HOMO)和最低未占据轨道(LUMO),评价光电子产生的难易程度。结果表明,Cr掺杂前后,氧化锌薄膜均为六方纤锌矿结构。Cr-ZnO/PET-GR和未掺杂的氧化锌(ZnO/PET-GR)纳米薄膜均为棒状,微量Cr的掺入使得ZnO纳米棒垂直度和致密度增大,纳米棒的直径减小。Cr元素主要以Cr^(3+)的形式存在。理论计算和试验均表明,Cr^(3+)掺杂使得载流子的复合效率显著降低,显著提高了其光催化效率。

The Cr-doped ZnO nanocomposites were prepared on the graphene coated flexible polyethylene terephthalate substrate by low-temperature hydrothermal method.The crystal structure,microscopic morphology,and surface chemical state were characterized by XRD,FE-SEM,and X-ray photoelectron spectroscopy(XPS).The electrochemical impedance(EIS)and photoluminescence spectroscopy(PL spectroscopy)were employed to investigate the optical and electrical properties of Cr-ZnO/PET-GR.The highest occupied orbital(HOMO)and lowest unoccupied orbital(LUMO)of the molecules before and after Cr^(3+) and Cr^(2+) doping in ZnO nanocomposites were calculated to evaluate the difficultly of photoelectron generation.The XRD results demonstrate that the ZnO nanocomposites before and after Cr doping are both hexagonal wurtzite structure.Moreover,Cr-ZnO/PET-GR and ZnO/PET-GR nanofilms are both nanorods,while better verticality and density of nanorods with smaller diameter were detected in Cr-ZnO/PET-GR compared to ZnO/PET-GR.Cr elements are mainly existed as Cr^(3+).Theoretical calculation and experiments demonstrate that the recombination efficiency of the carrier can be significantly reduced,resulting in obvious promotion of photocatalytic performance of ZnO nanocomposites.