The Influence of Samarium Doping on the Photoelectrochemical (PEC) Activity of SrTiO 3 for Solar Water Splitting

The effect of Sm 3+ doping (0–5 mol%) on the photoelectrochemical properties of SrTiO 3 was systematically investigated as a photoanode candidate for solar water splitting. Dense bulk ceramics synthesized via solid‐state route retained the cubic perovskite structure. Rietveld refinement of the 5 mol% Sm‐doped SrTiO 3 (Sm:STO) sample confirmed successful A‐site substitution with Sm. Photoluminescence emission spectra revealed enhanced emission intensities upon doping, with concentration quenching observed at 5 mol% Sm. UV–Vis diffuse reflectance spectroscopy indicated only a marginal bandgap narrowing (3.18 for pure STO to 3.14 eV for 5% Sm:STO), suggesting that band structure modification alone does not account for the enhancement in the PEC performance. The 1.5% Sm:STO photoanode exhibited the highest photocurrent density of 64 µA cm − 2 at 1.23 V RHE , nearly two orders of magnitude higher than the undoped SrTiO 3 reference. This improvement is attributed to Sm induced grain refinement, increased electrochemically active surface area, and partially to oxygen‐vacancy formation. Mott–Schottky analysis confirmed n‐type conductivity, while chronoamperometry tests verified the material's chemical stability over 3 h under continuous illumination. These findings show that Sm doping could be used to activate bulk SrTiO 3 ceramics, demonstrating the potential of customized perovskites as scalable photoelectrodes for solar water splitting.