Photocatalytic H2 evolution activity

The photocatalytic H₂ evolution experiments in aqueous HI solution (containing 20 vol% H₃PO₂ as a stabilizer) were executed in a homemade double-layered Pyrex vessel. A 300 W Xe lamp with a visible-light illumination (λ ≥ 420 nm, 100 mW cm⁻²) was employed as a light source for the photocatalytic reaction. In a typical photocatalytic H₂ evolution procedure, 10 mg of as-synthesized photocatalyst was introduced into 10 mL aqueous HI solution containing 20 vol% H₃PO₂ with the constant stirring rate, and then degassed with Ar through the reactor for 30 min to completely remove the dissolved air before irradiation. The reaction temperature was preserved at 25 °C by a circulation cooling water. The amount of evolved H₂ was detected every hour in a 6 h test by gas chromatography (GC-7890B, Agilent, America, TCD, with MS-5 Å molecular sieve column) with Ar as the carrier gas. The recycling photocatalytic experiment for the stability test of as-prepared photocatalyst was carried out every 6 h as a cycle.