Hydrothermal Synthesis, Crystal Structure, and Thermal Studies of CuSb₆O₈(SO₄)₂ and Its Applications toward Dye Management, Hydrogen Evolution Reaction, and Antibacterial Studies

Single crystals of a monophasic layered copper antimony oxy-sulfate, CuSb₆O₈(SO₄)₂, have been grown by the hydrothermal technique. SCXRD study reveals that it crystallizes in triclinic symmetry (SG: <i>P</i>1̅) and is comprised of [SO₄] tetrahedra, [SbO₄E] trigonal bipyramids, and [CuO₄] square planar moieties. No structural phase transition was observed even upon lowering the temperature up to 100 K. The structure consists of [(CuO₄)Sb₂O₅]<i>_n</i>-[Sb₂O₇(SO₄)]<i>_n</i> layers along [001] and is connected to each other through weak nonbonding interactions via oxygens of the [SO₄] tetrahedron and antimony atoms of the adjacent layer. It demonstrates high photocatalytic dye degradation efficiency, achieving 94.68 and 94.72% degradation of Methylene blue and Rhodamine B in the presence of 0.1 mL H₂O₂, respectively, with recyclability up to the sixth cycle with >90% efficiency. It also exhibits excellent HER activity with a low overpotential of 111 mV at 10 mA/cm² and a Tafel slope of 157 mV/dec in 1 M KOH. The compound exhibits strong antibacterial activity against several Gram-positive and Gram-negative bacteria as investigated by agar well diffusion method. TG-DTA shows good thermal stability of the compound with a decomposition temperature above 273 °C. The phase purity of the compound and its structural consistency after HER and photocatalysis were confirmed by PXRD analysis.