Enhanced photoelectrochemistry water splitting based on the bi-piezoelectric Z-scheme pn heterojunction of an n-CdTe/p-ZnO nanorods array

Abstract

An n-type Cd-excess CdTe (n-CdTeCd)/p-type Sb-doped ZnO nanorods (p-ZnONR,Sb)/indium tin oxide photocathode with a bi-piezoelectric Z-scheme pn heterojunction is prepared by hydrothermal method and electrodeposition for photoelectrochemistry (PEC) water splitting. At 0 V vs RHE under 100 mW cm−2 Xe lamp illumination in 0.5 M aqueous Na2SO4 stirred at 1500 rpm, the photocurrent density, H2 (O2 evolved at a Pt anode) yield, and the apparent Faradaic efficiency for this photocathode are −3.86 mA cm−2, 58.5 (28.6) μmol cm−2 h−1 and 84.7%, respectively. After examining the other similar semiconductor combinations of n-CdTeCd or p-type Te-excess CdTe (p-CdTeTe) with n-type ZnO nanorods (n-ZnONR) or p-ZnOSb,NR, the co-effects of bi-piezoelectric and pn-junction electric fields on the separation and transfer of photogenerated charges for PEC water splitting are discussed in detail. This work may help to better understand various heterojunctions and the electric-field-modulated photogenerated charges’ separation and transfer for the development of relevant fields.