Graphene-linked graphitic carbon nitride/TiO2 nanowire arrays heterojunction for efficient solar-driven water splitting

A novel structure composed of TiO2 nanowire arrays (NWAs) was designed and synthesized by decorating with graphene-linked graphitic carbon nitride (GCN) layers. It serves as a robust photoanode for high-performance solar-driven water splitting in an alkaline solution. The GCN layers were deposited on TiO2 NWAs by a facile electrophoretic method, producing an interconnected two-dimensional GCN nanosheets/one-dimensional TiO2 NWAs heterostructure. Under simulated solar light illumination (light intensity 100 mW cm(-2)), the optimal GCN/TiO2 NWAs photoelectrode produces a photocurrent density of 1.7 mA cm(-2) at 1.23 V versus reversible hydrogen electrode (RHE), which is around 2.6 times enhancement from that of pristine TiO2 (0.7 mA cm(-2) at 1.23 V vs. RHE). The photo-conversion efficiency of GCN/TiO2 NWAs is up to 0.92 % at a low bias potential 0.50 V versus RHE, 3.6 times higher than pristine TiO2 (0.27 % at 0.59 V vs. RHE). The improved photoelectrochemical activity is mainly because of the improved charge separation and transport within the heterojunction as well as enhanced light absorption.