Bi shell-BiOI core microspheres modified TiO2 nanotube arrays photoanode: Improved effect of Bi shell on photoelectrochemical hydrogen evolution in seawater

Photoelectrochemical (PEC) seawater splitting can relive the shortage of purified water feedstocks . However, the corrosion from seawater on the photoelectrode becomes an uncertain influence factor for PEC performance. Developing an efficient and stable photoelectrode is a challenge. Herein, we present a Bi–BiOI shell-core microspheres modified TiO 2 nanotube arrays (TNA) photoanode prepared via solvothermal method , affording superior PEC hydrogen evolution activity in simulated seawater under AM1.5G light, which is 3.8 and 7.6 times than those of BiOI/TNA and TNA, respectively. Solar-to-hydrogen conversion efficiency of Bi–BiOI/TNA reaches to 2.21% with Faradaic efficiency up to 85.7%. Based on the optical and PEC measurements, it is verified that surface plasmon resonance effect of metallic Bi promotes transfer and separation of photogenerated charge and enhances visible-light absorption, thus benefiting higher PEC performance. Especially, Bi shell efficiently hinders the corrosion of BiOI by seawater. Our work provides a novel paradigm of photoanode for efficient and stable PEC seawater splitting.