A wireless and redox mediator-free Z-scheme twin reactor for the separate evolution of hydrogen and oxygen

Abstract

A twin reactor was constructed for the separate evolution of hydrogen and oxygen during photocatalytic water splitting using a redox mediator free Z-scheme approach. In this work, the overall water splitting process was carried out in a single reactor with a Nafion membrane dividing into twin chambers where CuFeO2 and Bi20TiO32 are as hydrogen and oxygen photocatalyst powders respectively. Reduced graphene oxides were used as a collector extender for electron conduction during in a Z-scheme photocatalytic water splitting system. Branched copper wires were employed to enhance electron collection from the reduced graphene oxides in the twin reactor system used for water splitting under light illumination. The evolution rate of hydrogen and oxygen was 2.23 and 1.14 μmol/h, respectively in the twin reactor, which is close to the stoichiometric ratio of 2:1. As compared to a single reactor, photocatalytic water splitting with separate evolution of H2 and O2 using a twin reactor device is vital since it avoids the explosion potential and hydrogen-purification cost. This redox mediator-free device has the potential for a wider range of applications and reduced the resistance losses resulting from the wiring and the cost related to a mediator. Consequently, this twin reactor with a redox mediator-free approach provides a new opportunity for further improving the efficiency of solar energy conversion reactions.