Pressure‐Induced Dual‐Emission Enhancement of Hg(II)‐Activated CdI2 and Its Nanosheet‐Based Application for Hg(II) Ions Sensing

Abstract The layered transition metal dihalide CdI2 has been recognized as scintillator and nonlinear optics at temperatures ranging from that of liquid nitrogen to ambient, further exploring the strategy for its modulation in optical performance and advanced application still insufficient and indispensable. Here, a comprehensive study on photoluminescence and thermal properties for a newly developed CdI2‐modified material CdI2:Hg under both ambient and high pressure is performed. This investigation explores the modulation effects of high pressure, up to 15.2 GPa, on the photoluminescence dual‐emission characteristics, phase behavior, and laser tolerance of CdI2:Hg. It reveals a remarkable dual‐emission enhancement by 15–20 times and confirms the significant role of the evolution of energies associated with the self‐trapped exciton state under pressure. Despite the weaker thermal property of CdI2:Hg, significant pressure‐induced enhancement in laser ablation threshold caused by the improvement in thermal conductivity can be observed. Notably, uniform nanosheet CdI2 film is directly manufactured for the sensitive and inexpensive Hg2+ indicator in a hot‐air atmosphere. The present work provides fresh perspectives on the tuning of optical properties and the advanced utilization of CdI2‐related layered materials.