Piezocatalytic and doping effects synergistically enhance the oxygen evolution in Sb-doped zinc oxide nanorod arrays as a photoanode for photoelectrochemical water splitting

Highlights: This work demonstrates 98% improvement in the photocurrent density of photoelectrochemical water splitting of ZnO nanorods by p-type Sb doping and 28% more improvement by piezotronic effect through tensile strain, leading to an overall 154% enhancement through the synergistic effects. Abstract: An efficient separation and transport of charges is essential in order to enhance photoelectrochemical (PEC) water splitting efficiency. Herein, we report that PEC water splitting output performance of undoped ZnO nanorods (NRs) is firstly enhanced by p-type Sb doping on oxygen evolution reaction (OER), grown by a facile chemical bath deposition. The specimen with 2 at% Sb-doped ZnO NRs (2 at% Sb-ZnO NRs) yields the highest photocurrent density of 1.07 mA/cm² under a Xe lamp with a power of 100 mW/cm², two times that of the undoped ZnO NRs (0.54 mA/cm²). Additionally, piezotronic effect is applied to further enhance PEC output performance using an in-house fabricated device. When the sample of 2 at% Sb-ZnO NRs is subject to a strain varying from a compressive strain of ε = − 0.15% to a tensile strain of ε = 0.15%, the photocurrent density varies from 0.71 mA/cm² to 1.37 mA/cm² accordingly caused by the change of the piezopotential-induced Schottky barrier height. Therefore, compared to the strain-free condition of the undoped ZnO NRs, the PEC photocurrent density gained an enhancement of 98% by p-type Sb doping and a further enhancement of 28% by piezotronic effect through tensile strain, leading to 154% overall enhancement. In this work, we propose a feasible scheme to develop high-performance ZnO-based photoelectrodes for PEC water splitting. Graphical abstract: [Figure not available: see fulltext.]