Piezo‐Activated Metal‐Free Donor‐Acceptor Photocatalytic Overall Water Splitting System Toward Highly‐Efficient Simultaneous H ₂ and H ₂ O ₂ Production

ABSTRACT The potential mismatch of band structures to water redox potentials for most of photocatalysts restricts the development of photocatalytic overall water splitting (OWS). Herein, a well‐defined donor‐acceptor polymer model photocatalyst (HFPTP‐Bpy‐Hz), featuring an unsuitable band structure for OWS, was designed. It was demonstrated that the OWS ability of HFPTP‐Bpy‐Hz for H 2 and H 2 O 2 generation was activated by the bending of its unmatched conduction band in the piezo‐induced built‐in electric field, as well as the thermodynamically favorable two‐electron pathway for H 2 O 2 ‐evolved water oxidation on bipyridine structure. HFPTP‐Bpy‐Hz showed excellent metal‐free photo/piezo‐catalytic OWS performance for H 2 and H 2 O 2 generation (1795 and 1571 µmol·g −1 ·h −1 , respectively) better than the performances in literatures. Effective separation of photo‐generated carriers achieved by piezo‐induced built‐in electric field and hydrazone bond‐based electron transfer channel, and low energy barriers of water splitting in the presence of hydrazone bond linkage, collectively contributed to the outstanding photo/piezo‐catalytic OWS performance of HFPTP‐Bpy‐Hz. Furthermore, the hydrazone bond‐based positive correlation between the polarity of the polymer backbone and piezo/photocatalytic activity at the molecular level was clearly demonstrated through targeted regulation of connecting bonds and building blocks. This work offers valuable insights for constructing the promising solar light‐driven OWS systems using photocatalysts with unsuitable band structures.