Stability improvement of a Pt/TiO2 photocatalyst during photocatalytic pure water splitting

Abstract

The stability of a photocatalyst is a crucial indicator for its widespread use, which is significantly connected with deactivation and regeneration processes. Nevertheless, in the field of photocatalytic water splitting for hydrogen production, the deactivation and regeneration of photocatalysts have not been paid enough attention. In this work, the deactivation mechanism of a brookite TiO₂ nanoflutes decorated with Pt (Pt/b-TiO₂ NFs) photocatalyst used in photocatalytic pure water splitting was investigated, and simple and effective methods to improve stability were proposed as well. There are two reasons for the decrease of photocatalyst stability: the accumulation of H₂ and the adsorption of the product H₂O₂. The physical structure of the Pt/b-TiO₂ NF photocatalysts is stable during the reaction. As the reaction progresses, the products H₂ and H₂O₂ accumulate gradually, and H₂O₂ attaches more tightly to the photocatalyst surface, steadily replacing the adsorption site of the reactant H₂O. Hence, the forward reaction is suppressed and a sharp decrease in the adsorption of the reactant H₂O is observed. Timely transfer of large amounts of H₂ can avoid the inhibition of the forward reaction and thus stabilize the photocatalysts for more than 500 h at a time, which is 15–20 times more than that has been reported. To solve the adsorption problem of H₂O₂, the Pt/b-TiO₂ NF photocatalysts can be completely regenerated by mechanical disturbance. The same batch of the Pt/b-TiO₂ NF photocatalysts can operate continuously for at least 400 h. This work is of great significance for promoting the large-scale application of photocatalytic water splitting to produce H₂.