Temperature-induced selective-defect nucleation in (Cu3−XCoX) Pt filled graphitic carbon foams by controlled Raman-laser irradiation

Abstract

Introducing nanoscale level defects into graphene- and graphite-based materials has recently become a promising strategy for band gap manipulation. In this work we have focused our attention on the nucleation of boundary- and vacancy-defects in a novel type of graphitic carbon foam material filled with ferromagnetic (Cu3−XCoX) Pt. We have investigated such defect nucleation process by (1) temperature dependent Raman laser irradiation and (2) prolonged Raman laser irradiation at the fixed temperature of 400 °C. An unusual systematic increase in the D/D′ ratio with the increase of the temperature is reported, implying the presence of a transition from a boundary-defect configuration existing for the T-range of 25 °C–400 °C to a vacancy-defect configuration for the T-range of 450 °C–550 °C. Also, we show an anomalous decrease of the D and G band intensities with the increase of the temperature, attributable to a transformation of the multilayered carbon foam into a defect-rich monolayer-like carbon material at high temperature. This unusual effect was tuned/controlled also by varying the Raman-laser irradiation time for a chosen temperature, with an increase of D/D′ ratios from 3.55 to 7.36 after 1 min of irradiation. Such a variation in the Raman spectra characteristics implies also possible future band gap manipulation in analogy to the results recently reported in chlorinated graphene systems.