Elucidating Interfacial Water Structures and Photothermal Dynamics in Photocatalytic Water Splitting Reaction

Efficient photocatalytic water splitting for hydrogen production relies not only on semiconductor design but also on the configuration of interfacial water molecules and mass transfer processes, which remain underexplored. This study unveils a multidimensional synergy mechanism involving infrared light-thermal-electron-structure interactions in SrTiO ₃ -based photocatalytic systems. Systematic characterization using in-situ Raman spectroscopy revealed the cooperative mechanism between infrared-induced electronic excitation and thermal activation in SrTiO ₃ -based systems. Infrared radiation facilitates phonon-assisted indirect bandgap transitions in SrTiO ₃ while generating localized thermal gradients. Complementary in situ electron paramagnetic resonance analysis demonstrated that the thermally activated water interface environment enhances d-orbital electron spin activity of Co ²⁺ co-catalysts, which critically promotes proton-coupled electron transfer dynamics. Through synergistic exploitation of the light-thermal-electronic-structural multidimensional coupling effects, we realized a remarkable enhancement in solar-to-hydrogen conversion efficiency (1.58% vs. benchmark 0.82%). Thermodynamic and kinetic analyses further confirmed the existence of dual activation pathways. These findings provide a mechanistic understanding and theoretical foundation for optimizing photocatalytic systems for water splitting.