Al3+doping reduces the electron/hole recombination in photoluminescent copper ferrite (CuFe2-xAlxO4) nanocrystallites

Abstract

Nanocrystalline copper ferrite shows distinct photocatalytic properties, but it suffers from a high recombination rate of photogenerated electrons (e-) and holes (h+) due to its narrow bandgap. Herein, Al3+ doping is shown to reduce the (e-/h+) recombination rate and improve the charge carriers' availability in doped CuFe2-xAlxO4 (0 ≤ x ≤ 1) nanoparticles produced by a solid-state, mechanochemical process. CuFe2-xAlxO4 (0 ≤ x ≤ 1) nanoparticles exhibit the growth of a nanocrystalline cubic spinel lattice when annealed at 1000 °C. The lattice parameter is reduced by Al3+ doping due to the smaller ionic radius of Al3+ ions substituting bigger Fe3+ ions. However, a higher degree of sintering and greater crystallite size are observed for Al3+ doped samples. The surface morphology and topography also reveal an increase in the particle size, but significantly narrow size distribution and greater homogeneity. The effect of Al3+ doping on the optical properties of CuFe2-xAlxO4 (0 ≤ x ≤ 1) nanoparticles is demonstrated by a decrease in the photoluminescence signal that is attributed to the lower rate of (e-/h+) recombination. Thus, Al3+ doping increases transition time and improves the availability of charge carriers for potential photocatalytic applications.