Nitrogen cryostat

Room temperature absorption spectra were recorded with a Cary 4000 spectrophotometer (Varian). The CD spectra were measured using a Chirascan CD Spectrophotometer (AppliedPhotophysics). The fluorescence emission spectra were recorded using a Fluorolog 3.22 spectrofluorimeter (Jobin Yvon-Spex). The excitation wavelengths were 440nm, 475nm and 500nm and emission was detected in the 600–800nm range. Excitation and emission bandwidths were set to 3 nm. All fluorescence spectra were measured at OD 0.05 at the maximum of the Qy absorption band. Room temperature measurements were performed in 0.5M sucrose, 20mM Hepes (pH 7.5), 0.06% β-DM buffer. For 77K measurements a liquid nitrogen cooled device was used (Nitrogen Cryostat, Oxford Instruments). The samples were in 70% glycerol (w/v), 20 mM Hepes (pH 7.5), 0.06% β-DM buffer.

TEM images, HAADF-STEM, and EDX-mapping spectra were collected by a JEOL-F200 microscope. XRD patterns were obtained by using the Smartlab instrument (Cu Kα, λ = 1.5406 Å, Rigaku) over a diffraction angle (2θ) range of 3-60° with a step increment of 2θ = 0.02° at a rate of 2° min⁻¹. FTIR spectra were recorded by a Nicolet 560 spectrometer. Solid-state ¹³C NMR spectra were conducted on a JEOL JNM-ECZ-600R/M1 600 MHz spectrometer. The N₂ adsorption-desorption isotherms were determined by a Quantachrome surface area analyzer, and the sample powders were first degassed at 150°C for 24 h. The UV-vis DRS was detected by a Hitachi U-3010 spectrometer. Steady-state PL emission spectra and transient fluorescence lifetimes were obtained by a Jobin Yvon Horiba Fluorolog-3 spectrofluorometer. Temperature-dependent PL spectra were processed on an Edinburgh FLS 1000 spectrofluorometer equipped with Oxford Instruments nitrogen cryostat (Optistat DN) for temperature control. EPR spectra measurements were executed on a JES-FA200 X-band instrument. TG analysis was performed on a NETZSCH instrument in the N₂ atmosphere with a heating rate of 10°C min⁻¹. ICP-OES (iCAP 7000 Series, Thermo Fisher Scientific) was conducted to determine the Pt contents in all the samples.