The synergy of atomic-level charge transfer bridges and extra piezoelectric electric field endow efficient pure water splitting into H2O2 and H2

The sluggish dynamics of charge transfer and severe interfacial lattice mismatch across piezo-photocatalysts restrict the catalytic performance, thereby limiting their application. Herein, concurrent introduction of atomic-level charge transfer bridges and subsequently endowing them with extra piezoelectric electric field in a “one-stone-two-birds” manner via hydrothermal method was proposed to address above obstacles. Specifically, the (Bi₂O₂)²⁺ units were co-shared between (00 l) facet of CaBi₂Nb₂O₉ and (001) facet of BiOX (X = Cl, Br, I) and served as efficient atomic-level charge transfer bridges to provide a seamless interface, eliminated the space barrier and facilitated charge separation. These symmetrical inherently nonpiezoelectric co-shared (Bi₂O₂)²⁺ can be endowed with piezoelectric properties through structural distortion to alter their symmetry induced by the high electronegativity of halogens in BOX. Importantly, the enhanced piezoelectric performance difference coincides with the order of electronegativity and radius size of halogen species. The synergy of co-shared (Bi₂O₂)²⁺ units and concomitantly extra polarization electric field render more efficient S-scheme charge separation, revealing by theoretical calculations and experiment results. Consequently, the outstanding piezo-photocatalytic pure water splitting performance is achieved, outperforming that without co-shared (Bi₂O₂)²⁺ units, emphasizing the role of atomic-level charge transfer bridges. This work offers ingenious strategy for designing novel pure water splitting piezo-photocatalyst.