Fabrication of piezotronic ZnO p-n homojunction via metal/oxygen defects modulation for efficient photoelectrocatalysis

Homojunction is a viable alternative strategy to realize excellent charge separation for enhancing photoelectrocatalytic performance. However, the feasible regulation of the homojunction interface remains challenging. Herein, a ZnO n -p homojunction with the piezotronic effect is constructed via an in -situ solvothermal method for enhancing photoelectrocatalytic activity. ZnO nanorods are transformed from n -type to p -type ZnO nanoparticles with zinc vacancies, leading to the n -p homojunction. The optimal NPZ-36 exhibits a superior photocurrent density of 1.56 mA/cm 2 at 1.23 V vs. RHE and a high incident photon to current conversion efficiency of 75 % at 360 nm. Impressively, with the merits of inherent piezoelectric and photocatalytic properties of wurtzite ZnO, the piezoelectric -enhanced photoelectrochemical activity originates from the simultaneous promotion of bulk charge transfer and interfacial charge separation in ZnO n -p homojunction. The photocurrent density of NPZ-36 -900 can reach to 2.02 mA/cm 2 under the stirring rate of 900 rpm, which is 2.1 times higher than that of pure ZnO photoanode.