A Robust 2D Photo-Electrochemical Detector Based on NiPS₃ Flakes

Photodetectors fabricated from very thin two-dimensional (2D) materials with high photoelectric conversion efficiency have unprecedented potential to overcome the limitations of conventional photodetectors. In particular, recent interest in 2D metal phosphorus trichalcogenides (MPTs) has derived from their strong light absorption, tunable bandgap, and robust stability. Here, large and atomically thin NiPS₃ flakes, prepared by electrochemical cathodic exfoliation, are used as electrodes for a self-powered photo-electrochemical (PEC) detector. It exhibits high photocurrent density, sensitive responsivity, cycling stability, and excellent on/off behavior under sunlight in a 0.1 m KOH solution. The KOH concentration and the external potential affect the performance, indicating that it can be an excellent PEC-type detector. This work provides fundamental knowledge about PEC-type MPT photodetectors and reveals the great potential of NiPS₃ as an optoelectronic device.