First, using photocatalysts with the Chini clusters obtained at higher pH conditions (pH = 13) leads to a higher rate of H2 generation. The Chini clusters synthesized in higher pH conditions (pH = 13) are smaller, with a size of n = 4, while those synthesized at neutral pH (pH = 7) are larger, with a size of n = 7-8. It confirms that smaller clusters formed at higher pH are more efective in the investigated catalytic processes.