Van der Waals Black Phosphorus/Bi10O6S9 Heterojunction Harvesting Ambient Electric Field Energy for Enhanced Photoelectrochemical Sense

Ingenious utilization of ambient energy is a vigorous issue for heterostructure-type devices in evoking their performance in various applications. Using the van der Waals effect, two-dimensional black phosphorus is developed to bond with a unique Bi10O6S9 layer, which then forms a type-II heterostructure based on a truncated pyramidal Si/Ag/WO3 substrate. It is demonstrated that the ambient electric field can not only promote the separation and transfer of the electrons (and holes) excited by light irradiation but also induce additional electrons (and holes) to migrate in the same direction as that of those excited by light irradiation. Under the action of a 1100 V m–1 ambient electric field, the photoelectrochemical response current of light irradiation is increased 1.6 times, while the stability of the photoelectrochemical response current can retain 81.06% of the initial value even after 6000 s. The thin black phosphorus layer alone contributes 1.75 times the response current. On this basis, a sensitive device for monitoring the weak physiological electric field of a human arm assisted by light irradiation was developed, which shows wide application prospects in wearable devices.