Photocatalytic Water Splitting of Al-Doped Rh_xCr_2–xO₃/SrTiO₃ Synthesized by Flux Method: Elucidating the Role of Different Molten Salts

Abstract

Photocatalytic water splitting is a promising approach to converting solar energy into green hydrogen. As an effective photocatalyst, Rh x Cr2–x O3/SrTiO3 has been widely studied for water splitting, mainly synthesized using SrCl2 molten salt as the reaction media. This research systematically studied the effect of molten salts and Al doping in order to test and integrate the combinatorial effect of the modifications of SrTiO3-based catalysts. A series of SrTiO3 and Al-doped SrTiO3 (Al:SrTiO3) were synthesized by the flux method with three molten salts (NaCl, KCl, and SrCl2·6H2O) at different annealing temperatures (900 and 1000 °C). Cocatalyst, Rh x Cr2–x O3, was loaded on the surface of Al-doped SrTiO3 by impregnation and photodeposition methods for comparison. The photocatalytic performance of overall water splitting was evaluated in pure water under UV and AM 1.5G simulated sunlight. A significant improvement in photocatalytic activity was observed in Al-doped Rh x Cr2–x O3/SrTiO3. Especially Al-doped Rh x Cr2–x O3/SrTiO3 synthesized by KCl molten salt showed the highest hydrogen evolution rate with the synergy effect of molten salt and Al doping. Furthermore, hydrogen evolution rates were further enhanced by loading core–shell Rh x Cr2–x O3 using in situ photodeposition instead of impregnation, reaching 784 and 431 μmol h–1 g–1 H2 under 365 nm UV light and AM 1.5G irradiation, respectively.

Unleashing the Potential of Coupled Substituted 3D Niobate Perovskite Oxides in Cocatalyst-free Photocatalytic Hydrogen Evolution

“…Doping with trivalent metal ions (Eu 3+ and La 3+ ) have also shown to enhance the photocatalytic and optical activity of the compounds . Similarly, doping of SrTiO 3 with Rh, Al, La, Fe, Mn, Co, and Cr is reported to enhance the activity of the materials. − However, there are only few reports available for doping in NaNbO 3 toward their activity in photocatalytic hydrogen evolution. , In this study, visible-light active niobate perovskites are synthesized using coupled substitution strategy using alkaline earth and 3d transition metals. By selectively substituting different elements at the A and B sites, it is possible to tailor the properties of perovskite materials.…”