Excellent catalytic performance of mechanically alloyed AlCrFeMnTiZr0.5 high-entropy alloy for malachite green degradation.

• AlCrFeMnTiZr 0.5 HEA powder photocatalyst is prepared by mechanical alloying. • AlCrFeMnTiZr 0.5 catalyst exhibits good malachite green degradation under light. • Nano-reactants are mainly oxides or hydroxides of Al and Mn after catalysis. • Nanoparticles and nanosheets covering surface promote adsorption and degradation of MG. • Exfoliated nano-reactants and exposed fresh surface enhance degradation reusability. This work reports that the mechanical alloyed AlFeMnCrTiZr 0.5 high-entropy alloy (HEA) powder was used as catalyst for malachite green (MG) degradation. The HEA with dual solid solutions shows good catalytic performance under visible light. Its efficiency of reaching degradation saturation and maximum degradation rate are much greater than those of Fe0 powder. The oxides or hydroxides of Al and Mn nucleate and grow on the powder surface, existing in the form of initial nanoparticles and growing nanosheets, which promote the adsorption and catalytic degradation of MG. The exfoliated nanoreactants and exposed fresh powder surface of catalyst enhance the reusability and sustainability of degradation. The catalytic mechanism is mainly visualized by the synergy of chemical dye decomposition and physical dye adsorption. [ABSTRACT FROM AUTHOR]