Elastic strain induced improvement in the photocatalytic activity of semiconducting film exerted by the surface relief of Fe-Ni-Co-Ti alloy substrate

• Imposed tensile strain to the semiconducting film using substrate surface relief.
• Surface relief of FeNiCoTi substrate was characterized by AFM.
• Tensile strain narrowed the bandgap of the film.
• Strain improved the photocatalytic degradation rate of methyl orange by 30%.

Theoretical simulation has indicated that elastic strain is a universal and effective technique to modify the band structure of semiconductors; however, experimental work concerning elastic strain effects on the photocatalysis has been seldom reported due to the difficulty in imposing strain to the semiconducting films. Here, Fe-Ni-Co-Ti alloy was selected as a substrate to strain engineer an ultrathin semiconducting film by taking advantage of the surface relief for the first time. Surface relief originated from the martensitic transformation of FeNiCoTi substrate. Results showed that α–Fe2O3 and NiFe2O4 composite film was tensile-strained biaxially with an average value of 0.47%, and tensile strain narrowed the bandgap of the semiconducting film. In addition, strain contributed to a 30% acceleration in the methyl orange degradation rate than that of the strain-free film.

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