Escalab 250 axis ultra spectrometer

Brunauer–Emmett–Teller (BET) surface areas were measured by nitrogen adsorption at 77 K on an ASAP-2020 adsorption apparatus. Scanning electron microscopy (SEM) was carried out using a JSM-6510 (Rigaku, Osaka, Japan) operating at an accelerating voltage of 20 kV. Morphology and microstructure of Pd/alk-Ti₃C₂X₂ were characterized by transmission electron microscopy (TEM, Tecnai G20, FEI, Hillsboro, OR, USA) operating at an accelerating voltage of 200 kV. X-ray diffraction (XRD) characterization data were collected on a PANalytical X’eprt diffractometer (Egham, Surrey, UK) with Cu Kα radiation (40 kV, 40 mA) from 5° to 50°. X-ray photoemission spectroscopy (XPS) was performed on a Thermo ESCALAB 250 Axis Ultra spectrometer (Thermo, Waltham, MA, USA) using a monochromatic Al Kα (hν = 1486.6 eV). ICP-OES analysis was carried out on SPECTRO ARCOS spectrometer (SPECTRO, Kleve, Germany). The removal efficiency of the catalyst for 4-CP was analyzed by gas chromatography (GC, Agilent 7890A, Agilent Technologies, Santa Clara, CA, USA) with a flame ionization detector (FID) detector and PEG-20 M capillary column (30 m × 0.25 mm, 0.25 μm film) and nitrogen was used as a carrier gas.

Transmission electron microscopy (TEM) was conducted on JEM-2100F (JEOL, Akishima City, Japan). X-ray diffraction (XRD) patterns of the samples were recorded on a Regaku D/Max-2500 diffractometer (Tokyo, Japan) in the range of 2θ = 5–90°. X-ray Photoelectron Spectroscopy (XPS) was performed on a Thermo ESCALAB 250 Axis Ultra spectrometer (Waltham, MA, USA). Pd loadings in Pd/NPC samples and the leaching test during recycling were determined by ICP-OES with an SPECTRO ARCOS spectrometer (SPECTRO, Kleve, Germany).