Work

Valence state and defect modulation in reduced Sr-site deficient Pt/Sr0.95Ti0.9Cr0.1O3-δ perovskite for enhanced photocatalytic hydrogen production

Year: 2026

Type: article

Abstract: As the global energy landscape evolves from fossil fuels to a green hydrogen economy, efficient and stable semiconductor photocatalysts capable of harnessing visible light have become a key focus for optimizing solar-to-hydrogen energy conversion. Here, we rationally designed a Sr-site-deficient perovskite photocatalyst (R-Pt/Sr0.95Ti0.9Cr0.1O3-δ) synthesised by traditional solid-state method, followed by Pt impregnation and hydrogen reduction post treatment. The introduction of A-site deficiency effectively tunes the band structure and facilitates hydrogen reduction, resulting in twice the hydrogen evolution activity of stoichiometric analogs. On the other hand, A-site deficiency reduces overall cation charge and promotes Cr4+ formation. Through spectroscopic characterization and thermal analysis, Cr4+ was identified in the Sr0.95Ti0.9Cr0.1O3-δ perovskite, revealing unexplored oxidation state dynamics. Upon reduction, the main process is Cr4+ reduction to Cr3+, creating additional oxygen vacancies and removing hole-type Cr4+ trap sites. The resulting synergistic active sites greatly boost photocatalytic hydrogen evolution. Specifically, the R-Pt/Sr0.95Ti0.9Cr0.1O3-δ achieved a comparable H2 evolution rate of 118.73 μmol/gcat/h under full spectrum and 88.01 μmol/gcat/h under visible light (λ ≥ 420 nm) illumination, representing twice and 6.6 times enhancements relative to stoichiometric R-Pt/SrTi0.9Cr0.1O3-δ and unreduced Pt/Sr0.95Ti0.9Cr0.1O3-δ in visible light separately. This study provides new insights into the rational design of high-performance visible-light driven photocatalysts.

Source: Applied Surface Science

DOI: 10.1016/j.apsusc.2026.166370