G-C3N4/ITO/Co-BiVO4 Z-scheme composite for solar overall water splitting

Abstract

The g-C 3 N 4 /ITO/Co-BiVO 4 Z-scheme composite achieves overall water splitting without the participation of sacrificial agents (H 2 : 95.41 and O 2 : 40.23 μmol g −1 h −1 ), in which ITO accelerates charge transfer. And the activity is four times that of g-C 3 N 4 /Co-BiVO 4 . • All-solid-state g-C 3 N 4 /ITO/BiVO 4 Z-scheme photocatalyst is constructed. • Overall split of H 2 O into H 2 and O 2 is achieved without sacrificial agents. • ITO nanoparticle is used as solid-state mediator in g-C 3 N 4 /BiVO 4 system. • Z-scheme charge transfer mechanism is determined by ESR measurement in detail. The rate determining step of Z-scheme overall water splitting system is usually considered to be the charge carriers’ separation and transfer, which occurs between the hydrogen evolution photocatalyst (HEP) and the oxygen evolution photocatalyst (OEP). In this work, g-C 3 N 4 /ITO/Co-BiVO 4 Z-scheme composite in which g-C 3 N 4 as HEP, Co doped BiVO 4 as OEP and ITO nanoparticles as conductive mediator is designed and fabricated. Without using any sacrificial agents, the g-C 3 N 4 /ITO/Co-BiVO 4 composite exhibits 4 times higher than the g-C 3 N 4 /Co-BiVO 4 , with the H 2 and O 2 evolution rate of 95.41 and 40.23 μmol g −1 h −1 under full arc irradiation. The increase in photocatalytic activity can be attributed to the efficient carriers’ separation and transport induced by solid-state mediator ITO nanoparticles. In this work, a novel insight into rationally constructing effective all-solid-state Z-scheme system for overall water splitting will be given.