La, Al-dominated stabilization of Cr3+ in crystal-remolded SrTiO3 for efficient visible-light-driven overall water splitting

Achieving efficient solar-to-hydrogen conversion through visible-light-driven overall water splitting poses a significant challenge for particulate photocatalysts. Although bandgap engineering can be realized by ion doping, the introduced defects simultaneously enhance the recombination of electron-hole pairs. Herein, La/(Cr, Al) co-doped SrTiO3 was remolded via the ion implantation flux method. The La, Cr and Al achieve valence state equilibrium upon stabilizing the crystal lattice, resulting in visible-light absorption. The optimized La/(Cr, Al)-SrTiO3 photocatalyst exhibits an overall water-splitting reaction under visible light, yielding 73.2 μmol·h−1 for H2 and 35.0 μmol·h−1 for O2 with an apparent quantum yield of 1.44 % at 420 nm. Based on theoretical calculation, we proposed a La, Al-cooperated mechanism that a little Cr3+ was fixed by the surrounding Al3+, and the valence state was stabilized by La3+ during the crystal remolding, thereby giving the guidance for designing visible-light materials applied in overall water splitting.