Three-dimensional Bi2MoO6/TiO2 array heterojunction photoanode modified with cobalt phosphate cocatalyst for high-efficient photoelectrochemical water oxidation

Three-dimensional Bi2MoO6/TiO2 array was fabricated by decorating TiO2 nanorods (NRs) with Bi2MoO6 nanosheets (NSs). Compared with pristine TiO2 NRs and Bi2MoO6 NSs, the obtained Bi2MoO6/TiO2 heterostructure showed an excellent photoelectrochemical (PEC) performance. The photocurrent density reached 0.54 mA/cm2 at 1.23 V vs.RHE, 61% higher than that of bare TiO2 NRs array and almost tenfold higher than that of Bi2MoO6 NSs array on FTO. The high performance of heterostructured Bi2MoO6/TiO2 composite was mainly attributed to the expansion of absorption band edge and the enhancement of charge separation efficiency as well as the simultaneously increased chemically active area after introducing Bi2MoO6 on TiO2 arrays. Cobalt phosphate (Co-Pi) was further decorated on the surface of the Bi2MoO6/TiO2 to accelerate the surface water oxidation reaction, and the photocurrent density increased to 0.72 mA/cm2 at 1.23 V vs.RHE.