UV-vis diffuse reflectance spectra (DRS) were recorded on a Varian Cary 50 Bio Spectrophotometer with a Harrick Scientific Video Barrelino probe. A TESCAN MIRA3 FEG-SEM instrument with an Oxford Instruments Aztec Energy X-maxN 80 system was used to collect the SEM images and EDX mapping. X-ray diffraction patterns of the samples were measured with a PANalytical Empyrean Series 2 instrument using Cu Kα source operated at 40 kV and 40 mA. Inductively-coupled plasma optical emission spectrometry (ICP-OES) was carried out on a Thermo Scientific iCAP 700 spectrometer by the University of Cambridge (Department of Chemistry) Microanalysis Service.