Metallic nanoparticles loaded Al–SrTiO3 supported with RhCr2O3 and CoOOH cocatalysts for overall water splitting

Developing new renewable, carbon-neutral fuels to diminish the amount of released CO 2 in the atmosphere and to solve global challenges such as global warming and climate change is significant. Among them, hydrogen (H 2 ) is attracting much attention due to its high energy density, ease of transportation, and multiple means of production. To meet the global demand of H 2, photocatalytic water splitting is one of the most promising methods for large scale production. Herein, Al-doped SrTiO 3 photocatalyst (Al–SrTiO 3 ) was prepared by a molten flux method. Then, plasmonic metal nanoparticles (Au, Cu, Pt), and cocatalysts Rh/Cr 2 O 3 and CoOOH were selectively deposited onto the reductive and oxidative active sites of Al–SrTiO 3 using multi-step photodeposition-impregnation methods for water splitting and H 2 production under UV-rays, UV–Vis. Light, and visible light (λ ≥ 400 nm). Our results showed that, compared with Pt and Cu loaded Al–SrTiO 3 photocatalyst supported with Rh/Cr 2 O 3 and CoOOH cocatalysts, Au-loaded samples showed the highest H 2 production efficiency under both UV (920 μmol/h - EQE = 41% at 365 nm) and UV–Vis (100.5 μmol/h) rays. In addition, the amount of evolved H 2 decreased by increasing the weight ratio of Au nanoparticles (NPs) due to the overlap between Au NPs and Rh/Cr 2 O 3 cocatalyst. Although Au 0.3 wt%-loaded sample showed high activity under both UV and UV–Vis. Rays, it exhibited almost no efficiency under visible light because of the large bandgap of Al–SrTiO 3 (3.1 eV) and the poor absorption in the visible region. Visible light absorption was then enhanced by increasing the loaded amount of Au NPs and by separating Au NPs and Rh/Cr 2 O 3 cocatalyst responsible for H 2 evolution by combining both photodeposition and impregnation methods. Under visible light, Rh/Cr 2 O 3 -loaded Al–SrTiO 3 with 4 wt % Au NPs showed the highest H 2 evolution efficiency (41 μmol/3 h). This was attributed to the efficient hot electron transfer from Au NPs to Al–SrTiO 3 then to RhCr 2 O 3 , resulting in charge separation needed for efficient H 2 generation. Proposed reaction mechanism of water splitting and H 2 production by the prepared cocatalysts and Au NPs-loaded Al–SrTiO 3 under different light sources. • Al doped SrTiO 3 perovskite photocatalyst was prepared by a molten flux method. • Al–SrTiO 3 was loaded with plasmonic NPs, RhCr 2 O 3 , CoOOH cocatalysts for HE and OE. • Cocatalyst distribution on active sites of the main photocatalyst was controlled. • Water splitting and H 2 production was evaluated under UV, UV–Vis, and visible light. • Visible light active system was developed for H 2 evolution with no sacrificial agents.