Facile Liquid Phase Exfoliation Synthesis of 2D Non–Van der Waals TiB₂ Nanosheets for High–Performance Self–Powered Photoelectrochemical Photodetector With Underwater Application

Two–dimensional (2D) non–van der Waals (non–vdW) nanomaterials have been widely explored for their excellent physicochemical properties. Herein, 2D non–vdW titanium diboride nanosheets (TiB₂ NSs) are successfully fabricated via a facile top–down liquid phase exfoliation (LPE) approach. The as–prepared TiB₂ NSs are subjected to comprehensive structural and morphological characterization and then used to construct a photoelectrochemical (PEC)–type photodetector (PD). Systematic PEC measurements confirm that the device exhibits tunable photoresponse across both ultraviolet and visible light regions. Under 350 nm light irradiation in 0.1 M KOH electrolyte, the device achieves self–powered photodetection with a photocurrent (I_ph) of 109.10 nA cm⁻², photoresponsivity (R_ph) of 1.48 µA W⁻¹, and detectivity (D^*) of 4.93 × 10⁹ Jones. The PD also shows fast response/recovery speeds and excellent long-term stability under ambient conditions, with I_ph decreasing only 15% after one month. Notably, the self-powered TiB₂ NSs–based PEC photodetector exhibits stable photoresponse in simulated seawater, highlighting its promise for underwater optoelectronic devices.