Understanding improved photoelectrochemical performance in BaxSr1−xTiO3/TiO2 rod–shell nanostructures

Ferroelectric materials have been actively incorporated into photoelectrochemical (PEC) systems in recent years. The unscreened field induced by spontaneous polarization is believed to assist the charge separation and promote the solar energy conversion. However, the robustness of ferroelectricity in nanoscale heterostructures is plagued by detrimental size effects. Here, we report the unexpected improvement of PEC water splitting in BaxSr1−xTiO3/TiO2 rod–shell nanostructures with suppressed ferroelectric polarization. We propose that the enhanced electrical susceptibility due to ferroelectric instability facilitates the formation of ferroelectric polarons that protect the photocarrier transport from adverse recombinations with charged defects and opposite carriers, thus increasing the carrier lifetime and eventually boosting the cell efficiency. The results demonstrate the influence of dynamic polar order engineering on the photocarrier transport kinetics in ferroelectric-related PEC applications.