*2.4. Analysis*

The morphology of TSC-PA was investigated by scanning electron microscopy (SEM, JSM-5600LV, JEOL, Tokyo, Japan) equipped with energy dispersive X-ray spectroscopy. The EDS (IE250, Oxford Instrument, Abingdon, Oxfordshire, UK) was equipped with X-Max Silicon Drift Detector (SDD; the spectral resolution of 124 eV at Mn Kα) and an ultra-thin window; the active area of the SDD was 50 mm<sup>2</sup> . The phase composition of TSC-PA was analyzed by X-ray diffraction (XRD, Philips X'Pert Pro, PANalytical Netherlands, Almelo, Netherland) using Cu Kα radiation (λ = 0.15418 nm) within the 2θ-angle range from 5◦ to 90◦ . X-ray photoelectron spectroscope (XPS, PHI-5702, Physical Electronics Corporation, Chanhassen, MN, USA) was used to analyze the elemental chemical states of TSC-PA on the worn surfaces, and the binding energy of adventitious carbon (C1s: 284.8 eV) was used as the reference.
