In this paper, the structural and optical properties of reduced graphene oxide (rGO) doped vanadium pentoxide nanocrystalline films were studied. rGO was synthesized using modified Hummer method and confirmed by EDX, XRD and HRTEM. XRD measurements showed good fit with known card JCPDS 40-1296 of vanadium pentoxide with nanocrystals structure oriented toward the c-axis. The line of (002) in XRD graphs is getting weaker by the addition of rGO till nearly missing at the higher concentrations indicating intercalation of rGO within the vanadium layers. The average particle size measured decreased with increasing rGO content from 4.86 to 3.17 nm. Optical properties were studied by measuring the absorption, reflectance and transmittance of the prepared samples using double-beam UV–Vis spectrophotometers. The optical constants like refractive index n, extinction coefficient k, real and imaginary dielectric constants, absorption coefficient α, and optical band gap E op of the nanocrystalline films have been evaluated. The absorption coefficient decreases with increasing rGO content, which may be attributed to decrease in lattice distortion owing to rGO content due to the decrease of particle size as indicated in the XRD and HRTEM. Optical measurements revealed that there are two different optical gaps present. The optical gap Eop 1 was found to decrease with increase in rGO content, while the optical gap Eop 2 was found to increase with increase in rGO content. The carrier’s concentrations as well as the effective mass were calculated assuming hydrogen-like model. The good absorption in the UV region of rGO x V 2 O 5 ·nH 2 O films are promising candidate for solar cell photostabilizer applications.

中文翻译：

---

还原氧化石墨烯掺杂纳米晶五氧化二钒的表征和光学性能

在本文中，研究了还原氧化石墨烯 (rGO) 掺杂的五氧化二钒纳米晶薄膜的结构和光学性能。rGO 使用改进的 Hummer 方法合成，并通过 EDX、XRD 和 HRTEM 确认。XRD 测量显示出与已知卡片 JCPDS 40-1296 的良好拟合，其中五氧化二钒具有朝向 c 轴取向的纳米晶体结构。通过添加 rGO，XRD 图中的 (002) 线变弱，直到在较高浓度下几乎消失，表明 rGO 嵌入钒层内。测量的平均粒径随着 rGO 含量从 4.86 nm 增加到 3.17 nm 而降低。通过使用双光束紫外-可见分光光度计测量制备的样品的吸收率、反射率和透射率来研究光学性质。光学常数，如折射率 n，已经评估了纳米晶薄膜的消光系数 k、实部和虚部介电常数、吸收系数 α 和光学带隙 E op。吸收系数随着 rGO 含量的增加而降低，这可能是由于 rGO 含量导致晶格畸变的减少，这是由于 XRD 和 HRTEM 中表明的粒径减小。光学测量表明存在两种不同的光学间隙。发现光学间隙 Eop 1 随着 rGO 含量的增加而减小，而发现光学间隙 Eop 2 随着 rGO 含量的增加而增加。假设氢模型，计算载体的浓度以及有效质量。