Physical properties and photocatalytic activity of pulverized Ga-doped La₅Ti₂Cu_0.9Ag_0.1O₇S₅ powder

The photocatalytic activity of rod-like Ga-doped La₅Ti₂Cu_0.9Ag_0.1O₇S₅ (Ga-LTCA) particles exhibiting the one-dimensional conductivity is considered to be determined by the particle length relative to the charge carrier diffusion length (a few micrometers at most). In this work, Ga-LTCA particles with length of approximately 1 µm and a clear rod-like structure were prepared by thermal sulfidation, ball-milling, and post-annealing in sulfur vapor. Despite the small particle size and neat morphology, however, the photocatalytic H₂ evolution activity of the resultant Ga-LTCA was lowered, indicating that the degradation of the crystallinity during the ball-milling treatment was detrimental to the activity.