Hydrothermal synthesis and photocatalytic properties of Cu2(Fe1-xMnx)SnS4 solid solutions

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The structural and photocatalytic properties of the Cu₂(Fe₁₋ₓMnₓ)SnS₄ (CFMTS) series, a kesterite-stannite semiconductor system, were evaluated to assess their potential for photocatalytic applications. Structural characterization using X-ray diffraction (XRD) confirms that the CFMTS compounds crystallize in the stannite-type structure, with Mn substitution for Fe not significantly altering the lattice parameters. The photocatalytic performance was assessed through methylene blue (MB) degradation under visible light, demonstrating higher efficiency than TiO₂. The highest efficiency is observed in the terminal compositions (Fe-rich and Mn-rich) which can be linked to their higher BET-specific surface area. A strong correlation between structural distortion (η = c/2a) as well as Cu/(Fe+Mn+Sn) ratio, and photocatalytic activity is also observed. An increase in distortion parameter (η = c/2a) negatively impacts photocatalytic efficiency. The optimal Cu/(Fe+Mn+Sn) ratio range from 0.81 to 0.89. These results highlight the significance of precise chemical composition control in tuning the photocatalytic activity of CFMTS materials. The study demonstrates that Cu₂(Fe₁₋ₓMnₓ)SnS₄ is a promising candidate for photocatalytic applications, with potential extensions to energy conversion and environmental remediation.