Strain-induced charge delocalization achieves ultralow exciton binding energy toward efficient photocatalysis.

The exciton effect is commonly observed in photocatalysts, where substantial exciton binding energy ( ) significantly hampers the efficient generation of photo-excited electron-hole pairs, thereby severely constraining photocatalysis. Herein, we propose a strategy to reduce through strain-induced charge delocalization. Taking TaO as a prototype, tensile strain was introduced by engineering a crystalline/amorphous interface, weakening the interaction between Ta 5d and O 2p orbitals, thus endowing a delocalized charge transport and significantly lowering . Consequently, the of strained TaO nanorods (s-TaO NRs) was reduced to 24.26 meV, below the ambient thermal energy (26 meV). The ultralow significantly enhanced the yield of free charges, resulting in a two-fold increase in carrier lifetime and surface potential. Remarkably, the hydrogen evolution rate of s-TaO NRs increased 51.5 times compared to that of commercial TaO. This strategy of strain-induced charge delocalization to significantly reduce offers a promising avenue for developing advanced semiconductor photoconversion systems.