Remarkable enhancement on photoelectrochemical water splitting derived from well-crystallized Bi2WO6 and Co(OH)x with tunable oxidation state

Abstract

Bismuth tungsten oxide (Bi2WO6) has been extensively utilized as a promising photocatalyst for water splitting and contaminant degradation. However, its applications as the photoanodes for photoelectrochemical (PEC) water splitting have been greatly restricted owing to the intrinsically poor charge transport and sluggish oxygen evolution reaction (OER) kinetics. Herein, we demonstrated that the PEC performances of Bi2WO6 photoanodes could be remarkably enhanced by the well-crystallized construction, which could achieve the favorable conductivity for the bulk charge transport. More importantly, amorphous Co(OH)x nanofilms with optimized oxidation state were decorated on Bi2WO6 photoanode by a facile impregnation method, an unprecedented photocurrent density of 0.94 mA/cm2 and a high surface charge separation efficiency of 98% at 1.23 VRHE has been achieved, more than 58-fold enhanced OER activity compared with traditional Bi2WO6 sample. These results demonstrated that the appropriate crystal construction and cocatalyst decoration with tunable oxidation state could serve as an effective strategy toward developing high-efficiency PEC water splitting systems.