D8 instrument

X-ray powder diffraction (XRD) was performed to investigate the mineralogical composition of three samples from FU (FU1–FU2–FU3) and three from TI (TI1–TI2–TI3). The FU1 and TI1 samples were collected from the soil immediately below the corresponding biocrust (0–0.5 cm); the FU2 and TI2 samples spanned a depth of approximately 2–5 cm, and the FU3 and TI3 samples were obtained as a mixture of the corresponding FU1 + FU2 and TI1 + TI2 samples. Dried samples were ground into a powder in a Fritz Pulverisette P9 rotor mill until they could pass through a 230 ASTM sieve. Random powders were obtained using the Niskanen¹¹³ method, and oriented aggregates of fractions were used for the identification of sheet silicates according to the Pansu and Gautheyrou¹¹⁴ method. The collection of XRD data was performed using a Bruker D8 instrument with the Diffrac Plus System, Cu-Kα radiation, and a beam voltage and a current of 40 kV and 20 mA, respectively; a Ni filter, a step size of 0.03°2θ, and a step time of 96 s were used. The EVA program in combination with the ICDD database was used for data evaluation following the Warshaw and Roy¹¹⁵ method for the identification of sheet silicates. Semi-quantitative estimates of the mineral phases were carried out according to Davis et al.¹¹⁶ . XRD analysis was performed at the X-ray powder laboratory of the SCSIE Service of the University of Valencia.

A Bruker D8 instrument was used for the X-ray diffraction measurements. Chemical analyses were performed with X-ray photoelectron spectroscopy (XPS) by using a PHI 5000 Versaprobe-Scanning ESCA Microprobe. A 100 μm diameter monochromatic Al Kα X-ray beam (1486.6 eV) was used for the measurements. For the wide survey scans and high-resolution spectra, the hemispherical analyzer pass energy was maintained at 187 eV and 11.8 eV respectively for 3 cycles. The measurements were performed using 1 eV per step and 0.1 eV per step for wide survey scans and high-resolution scans, respectively. The PL data (excitation, emission, and decay curves) were recorded by using a Cary Eclipse fluorescence spectrophotometer with a xenon lamp as the excitation source in the phosphorescence mode. A 325 nm He–Cd laser was utilized to record PL spectra at different temperatures. A Philips CM100 Analytical Transmission Electron Microscope (TEM) was used to obtain information about the size distribution of the nanoparticles. Thermoluminescence (TL) glow curves were measured by using a Nucleonix system with heating rate of 5 K s⁻¹. A 254 nm UV lamp and USB200 Ocean Optics spectrometer were utilized for the prolonged UV irradiation experiment.

Na₆TeW₆O₂₄·22H₂O (TeW₆) was prepared according to the published procedure and characterized by IR spectroscopy.^{26 (link)} All reagents were purchased from commercial sources, and used without further purification. Elemental analyses were determined by inductively coupled plasma mass spectrometry (ICP-MS) with PerkinElmer NexlON 350X spectrometer and the Elemental Analyser (C, H, N). FT-IR spectra (KBr pellets) were recorded with a Nicolet 170SX-FT/IR spectrometer. Thermogravimetric analyses were carried out with a TG-DTA 6200 device at a heating rate of 10 °C min⁻¹ under nitrogen atmosphere. Powder X-ray diffraction (PXRD) data were recorded on a Bruker D8 instrument equipped with graphite-monochromatized Cu Kα radiation (λ = 0.154060 nm; scan speed = 8° min⁻¹; 2θ = 5–50°) at room temperature.