XP spectra were recorded using a VG ESCALAB iXL instrument

XP spectra were recorded using a VG ESCALAB 220iXL instrument with monochromatic Al Kα radiation (E = 1486.6 eV). Peaks were fitted to Gaussian–Lorentzian curves after Shirley background subtraction. The A 205804 binding energy was referenced to the Ti 2p3/2 peak of TiO2 at 458.8 eV. For quantitative analysis, the peak areas were determined and divided by the element-specific Scofield factor and the detector-depending transmission function.
In situ UV–vis analysis was performed in a setup explained elsewhere [27]. Shortly, ABF-STEM spectra were collected using an AvaSpec UV–vis is systematics spectrometer (Avantes) equipped with a DH-2000 deuterium-halogen light source and a CCD array detector. BaSO4 was used as a white reference material. High temperature reflection UV–vis probes consisting of six radiating optical fibers and one reading fiber were placed inside the furnace facing the quartz reactors. All spectra were calculated as Kubelka–Munk function F(R) according to Eq. (1):equation(1)F(R)=(1−R∞)22×R∞where R∞ is the reflectance.