*2.2. Characterization*

Luminescence emission measurements were obtained with an FS5 (Edinburgh, UK) conjugated with 808 nm (CNI, MDL-III-808-2.5W, China), 793 nm (CNI, MDL-III-793-2.0W, China), and 980 nm (CNI, MDLIII-980-2.0W, China) diode lasers at room temperature. The decay curves were recorded by a lifetime spectrometer (FS5, Edinburgh, UK), in conjunction with pulsed 808 nm, 793 nm, and 980 nm diode lasers and a picosecond pulsed light emitting diode (EPLED-270). Low-resolution transmission electron microscopy (TEM) measurements were carried out on an HT7700 field emission transmission electron microscope operated at an acceleration voltage of 120 kV. The energy-dispersive X-ray (EDX) spectrum was obtained with an HT7700 field emission transmission electron microscope equipped with an Oxford Instruments system. High-resolution TEM images were obtained using an FEI Talos F200S transmission electron microscope operated at an acceleration voltage of 200 kV. HAADF-STEM and elemental mapping images were obtained using an FEI Talos F200X transmission electron microscope. Powder X-ray diffraction (XRD) analysis was performed on a Rigaku D/Max-2200 system equipped with a rotating anode and a Cu K α radiation source (λ = 0.15418 nm). The excitation power density was measured using a TS5 laser power densitometer (Changchun New Industries Optoelectronics Technology, China). UV–vis absorption spectra were obtained using a PerkinElmer LAMBDA 750 ultraviolet–visible–near-infrared spectrometer and a Hitachi U-3010 spectrophotometer. All spectra were recorded under identical experimental conditions unless otherwise noted. Key experiments were repeated three times, and all other experiments were repeated twice.
