Resistive switching in 2D bismuth oxyhalide nanosheets for nonvolatile memory and emulation of leaky integrate-and-fire functions

[Display omitted] •BiOBr nanosheet demonstrates non-volatile resistive switching behaviors with a large ON/OFF ratio, long time retention and good endurance.•The BiOBr memristor can retain good resistive switching behaviors without significant degradation when immersed in different chemical solvents.•The BiOBr0.7Cl0.3 nanosheet shows volatile threshold switching behaviors which can be utilized to emulate the leaky integrate-and-fire function. The resistive switching (RS) behaviors have been widely studied in a large number of two-dimensional (2D) materials. Bismuth oxyhalides have emerged as a typical ternary 2D layered material recently. However, the studies focusing on the RS behaviors in 2D bismuth oxyhalides are still limited. Herein, the RS behaviors in 2D BiOX (X = Cl, Br and Cl + Br) nanosheets have been systematically studied. 2D BiOX nanosheets are exfoliated from their bulk materials which are synthesized by a hydrothermal method. Vertical memristors with Pt/BiOX/Pt sandwiched structures have been fabricated for RS measurements. Among them, 2D BiOCl nanosheet has no RS behaviors. BiOBr nanosheet demonstrates non-volatile bipolar RS behaviors with a large ON/OFF ratio (∼105), long time retention (104 s) and good endurance (280 cycles) as well as good environmental stability, suggesting potential applications in non-volatile memory. Furthermore, BiOBr0.7Cl0.3 nanosheet shows volatile threshold switching (TS) behaviors with the ON/OFF ratio up to 105. The device with TS behaviors can be utilized to emulate the leaky integrate-and-fire (LIF) functions in biological synapses. This work demonstrates a new material with non-volatile or volatile RS behaviors, providing a new TS device for emulation of LIF activity.