Nanoscale Mn3O4 Thin Film Photoelectrodes Fabricated by a Vapor-Phase Route

α-Mn3O4 (hausmannite) nanostructured films were fabricated by chemical vapor deposition (CVD) on indium tin oxide (ITO)-coated glass substrates from a β-diketonate–diamine Mn(II) precursor. Materials were grown in a N2 + O2 atmosphere in the presence of water vapor, investigating the influence of growth temperature and total pressure on the system structural, compositional, morphological, and optical properties through a multitechnique characterization approach. The obtained α-Mn3O4 nanodeposits were ultimately tested as catalysts in the photoelectrochemical (PEC) splitting of water under simulated solar illumination, with particular focus on the interplay relationships between the adopted preparative conditions and the resulting functional performances. The amphoteric semiconducting behavior along with the PEC properties markedly dependent on the deposit nanoscale organization opens interesting avenues to an eventual implementation of the target materials in view of sustainable applications.