Cu₂ZnSnS₄ (CZTS) as a promising candidate for hydrogen storage: Structural and spectroscopic insights

Cu₂ZnSnS₄ (CZTS), well-known for its use in photovoltaic and photocatalytic systems, has been studied as a solid-state hydrogen storage material. At 10 bar hydrogen pressure, structural and spectroscopic analysis revealed unambiguous lattice changes in the form of enhanced lattice parameters (a = 5.41 Å, c = 10.754 Å), a reduction in crystallite size from 66.37 nm to 56.70 nm. Raman and FTIR spectra confirmed hydrogen incorporation through vibrational mode changes and S–H stretching band emergence. A-mode near 336 cm⁻¹, including intensity changes and slight shifts, reflecting hydrogen-induced strain and defect interactions within the lattice. Through the emergence of an S–H stretching band around 2369 cm⁻¹, which was absent in the pristine sample. The material was observed with a high specific surface area, enhancing the adsorption kinetics for hydrogen. Storage capacity was 0.9 wt%, and the rate of desorption was 0.0108 m³/h at 200 °C. TGA demonstrated enhanced mass loss behavior in hydrogenated samples, suggesting modified thermal stability after hydrogen treatment. Gas chromatography analysis confirmed clean and selective hydrogen release. These findings make CZTS a low-cost and structurally versatile material with a promising reversible hydrogen storage solution in energy conversion applications.