Usb4000 uv vis spectrometer

Illumination was directed onto the sample through an Ocean Optics UV-Vis-NIR optical fibre that was connected to an Ocean Optics HPX-2000 light source that spans approximately 300 nm to 850 nm. An Ocean Optics 74-ACR collimating lens directed light from the end of the fibre to the sample surface. The reflected light was collected using a similar lens and optical fibre that was itself connected to an Ocean Optics USB4000-UV-VIS spectrometer19 (link). The angle of illumination and of detection could be separately set and controlled to a resolution of 0.5°. For a series of chosen fixed illumination angles, the collection fibre was stepped in 2° angle steps in an arc over the sample, and reflection spectra were recorded at each angular position. Reflectance intensity from samples was normalised against an Ocean Optics WS-1 white reflectance standard.

The phase composition of g-C₃N₄ was identified by XRD, recorded on a Rigaku D/max-3B X-ray diffractometer (Cu-K_α radiation, λ = 0.15418 nm) over the 2θ range of 10°-60° at 40 kV and 30mA. The chemical groups in g-C₃N₄ structure were confirmed by FT-IR, operated on a Nicolet Nexus infrared spectrometer after mixture of g-C₃N₄ sample with spectroscopic grade KBr (300 mg). The crystal morphology and microstructure of g-C₃N₄ were observed by SEM and TEM, realized on FEISirion200 scanning electron microscope and JEOL JEM-2010 transmission electron microscope, respectively. X-ray photoelectron spectroscopy (XPS) with Al Kα X-rays radiation (AXIS ULTRADLD, Kratos) was used to investigate the element compositions and surface properties of the samples. The binding energy was corrected using C1s (284.6 eV) as the internal standard. DRS spectra, recorded in the range of 400–800 nm, were implemented on an USB4000 UV-vis spectrometer (Ocean Optics) equipped with an integral sphere, using a standard template provided by South Africa Optics as the reference. The BET specific surface area of g-C₃N₄ was measured on a Sibata SA-1100 surface area analyzer, according to the nitrogen adsorption-desorption data at liquid nitrogen temperature. Surface Zeta potentials of g-C₃N₄ were examined by Zeta potential analyzer (Nano-ZS90) at different pH values.