Acronyms: XRF = x-ray fluoresencence; RBS = Rutherford Backscattering; XRD = x-ray diffraction; SEM = scanning electron microscopy; AFM = atomic force microcopy; PES = photoelectron spectroscopy, with x-rays (XPS) and ultraviolet (UPS); KP = Kelvin probe measurements, SECM = scanning electrochemical microscopy, PL
= photoluminescence; FTIR = Fourier transform infrared spectroscopy