Uv 550 spectrophotometer

Experimental band gaps of MONs were obtained by collection from literature^{3,19–50 (link)} and by experimental determination.
To control variables that influence band gaps of MONs as much as possible and to ensure the consistency of collected band gaps, a qualified data point from literature must meet the following demands: size of material is in the nanometer scale; particles must be spherical or approximate a spherical shape; particles have a single chemical makeup without any chemical modification on the surface; characterizations including X-ray diffraction, which verifies the crystalline structure of MONs, and UV-vis spectroscopic analysis are required.
Seven kinds of MONs (5 nm anatase-TiO₂, 25 nm anatase-TiO₂, 40 nm anatase-TiO₂, 100 nm anatase-TiO₂, 40 nm rutile-TiO₂, 100 nm rutile-TiO₂ and 50 nm ZnO) bought from Aladdin (http://www.aladdin-e.com/) were prepared for UV-vis spectroscopic analysis using UV-550 spectrophotometer produced by JASCO Corporation. To minimize possible errors, each determination for each material was repeated three times and the eventual outcome is the arithmetic mean of parallel experiments. The raw data of UV-vis spectroscopic analysis were transformed according to the Kubelka–Munk equation.⁵¹ The total data set of band gaps of MONs was split randomly into a training set and a validation set with a ratio of 3 : 1 (30 : 10).