Hydrogen production from NaBH₄ hydrolysis over chemically reduced TiO₂-based Ru nanocomposites and their antimicrobial performance

Abstract Herein, Ru⁰/TiO₂ nanocomposites containing 0.5 wt% Ru were prepared via a simple wet-impregnation route followed by chemical reduction and were thoroughly characterized by XRD, FTIR, SEM, TEM, and EDS analyses. The nanocomposite exhibits high activity toward the hydrolysis of NaBH₄ in water under relatively mild conditions (300 mM NaBH₄, without added base). Systematic variation of NaBH₄ concentration and catalyst loading shows that the hydrogen generation rate is essentially first order in both NaBH₄ and Ru⁰/TiO₂, yielding hydrogen generation rates in the range of ≈ 335.6 mL·min⁻¹·g_cat⁻¹ and turnover frequencies (TOF) of ≈ 938.30 h⁻¹ between 25 and 40 °C. Temperature-dependent kinetic measurements afforded an apparent activation energy of 32.37 kJ·mol⁻¹ together with ΔH‡ = 29.82 kJ·mol⁻¹ and ΔS‡ = -143 J·mol⁻¹·K⁻¹, indicating an energetically accessible yet highly ordered transition state at the Ru/TiO₂ interface. The catalyst retains ~ 36% activity after 4 cycles. In addition, Ru⁰/TiO₂ nanocomposites display strong antibacterial activity against both Gram-positive and Gram-negative bacteria, achieving growth inhibition above 90% at 500 µg·mL⁻¹. The dual functionality of Ru⁰/TiO₂ in highly efficient NaBH₄ hydrolysis and pronounced antimicrobial behavior highlights this nanocomposite as a versatile platform for practical chemical hydrogen storage and integrated energy and environmental applications.