Controllable phase transition dependent photoinduced charge separation in CuFe2O4 for photocatalytic hydrogen evolution

Abstract

In this paper, the phase transition process from spinel CuFe₂O₄ to inverse spinel is controlled by adjusting the calcination temperature, and the ratio of the two phases is determined by Rietveld structure refinement. It was found that the proportion of the inverse spinel phase increased as the temperature increased, while the spinel phase decreased. Moreover, the ratio of the two phases largely determines the photocatalytic performance of CuFe₂O₄, which exhibits a volcano shape relationship between the inverse spinel/spinel ratio and the photocatalytic hydrogen evolution performance. Photoluminescence spectroscopy, surface photovoltage spectroscopy and density functional theory calculations were used to resolve the photoinduced charge behavior resulting from the phase transition. It was found that the optimal material with an inverse spinel/spinel ratio of 65.38% has a significant surface state that can capture photoinduced electrons, thus exhibiting a high photocatalytic reduction performance.