TiO2/black phosphorus heterojunction modified by Ag nanoparticles for efficient photoelectrochemical water splitting

How to improve photon absorption, photoelectric conversion efficiency, and carrier separation and transfer efficiency is a huge challenge for promoting the efficiency of photoelectrochemical (PEC) water splitting. Herein, the black phosphorus nanosheets (BPNs) was assembled on the surface of TiO2 nanorods arrays (TiO2 NAs) through electrostatic attraction to form TiO2/BP heterojunction material. Meanwhile, Ag nanoparticles were successfully loaded on the surface of TiO2/BP heterojunction material to form Ag nanoparticles modified TiO2/BP heterojunction composite material. The TiO2/BP heterojunction modified by Ag nanoparticles nanostructures exhibited a remarkable enhancement in the PEC water splitting in comparison with the pristine TiO2. Photoelectrochemical performance at 1.23 V vs. RHE bias-potential under 100 mW cm−2 solar light illumination shows that synthesized Ag–TiO2/BP photoanode displaying the highest photocurrent density of 1.74 mA cm−2, which is practically 3.34 times higher than that of pristine TiO2 (0.52 mA cm−2), presenting a significantly improved PEC performance for water splitting. After 18 months, the photocurrent of synthesized Ag–TiO2/BP photoanode can still reach 1.63 mA cm−2, and the performance is stable. It demonstrated that the formation of heterojunction by electrostatic attraction of TiO2 and BP and then modification with Ag nanoparticles is an effective strategy for improving the PEC water splitting.