Electron separation and migration for photoelectrochemical water splitting with novel nanostructured fan-wings of ZnO-porous Bi2O3@CNF hybrid composite

Abstract

Coupled semiconductors with 1D carbon structures must be urgently developed. Herein, novel morphological semiconductors, namely fan wing-shaped ZnO and porous flower-shaped Bi2O3, are created, and the structural ZnO–Bi2O3 composite is impregnated with carbon nanofiber CNF. The performance of the generated heterohybrid and pure nanostructures for photoelectrochemical water splitting is assessed using a material for the anode. Compared with pure fan-wing type ZnO and porous flower type Bi2O3 nanostructures, the ZnO–Bi2O3@CNF heterohybrid exhibits a fourfold higher photocurrent density (1.7 mA/cm2) vs RHE by linear sweep voltammetry, and strong photocurrent response with continuous light irradiation and without light irradiation for 5 h. These photoelectrochemical enhancements are due to increased visible light absorption, higher surface active-sites, and effective charge separation enabled by the heterojunction formation between ZnO and Bi2O3. The CNFs impregnated with ZnO–Bi2O3 operate as electron sinks and/or acceptors, thereby decreasing the rate of recombination, facilitating the migration of electron–hole pairs to the catalyst surface, and improving the overall water splitting performance. Thus, this study presents an alternate structural layout and enhanced photoelectrochemical activity of ternary heterostructures. Additional materials with comparable structures can be used in this method to create efficient heterojunctions.