New insights into the formation of multi-core–shell mesoporous SnO2@SnS2 nanostructures

SnO2@SnS2 multi-core–shell heterostructures were synthesised via chemical conversion of mesoporous raspberry-like SnO2 nanocrystals. In the syntheses, different concentrations of a sulphide precursor (thioacetamide) were applied. The samples were analysed using scanning and high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results revealed the presence of surface defects (Sn2+, oxygen vacancies) on the raspberry-like surface, which play a crucial role in the chemical conversion reaction. With an increasing amount of thioacetamide, additional redox reactions occurred in the system (Sn4+/Sn2+, S2−/S0). The highest precursor concentration led to the microstructural disintegration and phase composition change.