A simple sol-gel method for the synthesis of Pt co-catalyzed spinel-type CuFe2O4 for hydrogen production; the role of crystallinity and band gap energy

In this investigation, spinel-type copper ferrites (CuFe2O4) at different calcination temperatures (600-900 degrees C) were produced using a facile citric acid-assisted sol-gel method. The crystal structure, morphology, optical, and electrical properties of the as synthesized photocatalysts were comprehensively characterized. XRD and UV-vis diffuse reflectance spectra (UV-vis (DRS)) showed that the phase structure and the band gap energy of the copper ferrite are strongly correlated to the applied calcination temperature. TEM results investigated that the copper ferrites calcined at higher temperatures presented large particle sizes and crystallized very well. In addition, the photocatalytic activity was tested for hydrogen production in the presence of methanol, with and without Pt nanoparticles as a cocatalyst. The results indicated that the CuFe2O4 annealed at 900 degrees C (CuF-900) has higher hydrogen production activity than photocatalysts calcined at lower temperatures in the presence and absence of Pt, which is mainly assigned to the higher crystallinity, and narrower bandgap energy. Moreover, this study explained in more detail the role of Pt nanoparticles in enhancing the photocatalytic activity of CuF-900. This work introduces a new direction of thinking for the tetragonal phase structure as an efficient photocatalyst for hydrogen production.

Automated summary

Spinel-type copper ferrite materials were prepared at different calcination temperatures using a citric acid-assisted sol-gel method. The influence of calcination temperature on the crystal structure, morphology, optical, and electrical properties of the materials was investigated. It was found that higher calcination temperatures resulted in larger particle sizes and better crystallinity. Photocatalytic activity for hydrogen production was also tested, and the material calcined at 900 degrees C exhibited higher activity due to its higher crystallinity and narrower bandgap energy. The role of Pt nanoparticles in enhancing the photocatalytic activity was further explained.