Stability of reduced polypyrrole

Characteristics of vibration modes of polypyrrole on surface-enhanced Raman scattering spectra

“…Namely, more oxidized PPy with a higher conductivity is always accompanied by a higher doping level. In previous studies [33,43], the correlation between the conductivities of PPy films in various states with their corresponding Raman peak positions of backbone stretching of C@C bonds has been established. However, no further details have been reported, such as the correlation between the conductivity and the double peak intensities of C-H inplane deformation of PPy, or the assignment of the peaks.…”

“…As reported in the previous study [49], the higher doping level of 0.37 of sample 5b, but a corresponding markedly lower conductivity of 9.5 S cm À1 , reveals that over-oxidation [50] and a side reaction, which competes with the film-forming reaction [26], occur during polymerization of PPy at 1.2 V vs. AgjAgCl, resulting, to some extent, in ring opening and pyrolysis. In previous studies [33,44], the correlation between the conductivities of PPy films in various states The relative intensity is the difference of the intensities of the peak and the background defined as the valley between the double peaks of ring stretching. a Described in Section 2. b Calculated from the ratio of the relative intensity of the peak at high frequency to that of the peak at low frequency.…”

“…Many researchers [30,31,35,41,42] have focused on the former peak because of poor spectral results or the latter peak becoming insignificant, perhaps disappearing, when the conductivity of PPy is low. Some efforts have also been made to correlate the conductivities of PPy films in various states with their corresponding Raman peaks of backbone stretching of C@C bonds [33,44] and doping levels obtained from XPS analysis [28,29]. Nevertheless, the correlation has not yet been made between the conductivity of PPy and the relative intensities of Raman peaks of C-H in-plane deformation of PPy.…”

“…As we know, Raman spectroscopy [30][31][32][33] is an essential method to evaluate the structure situation of PPy in various states. Nevertheless, the information provided can be reduced due to weak signals or interference from noise [30,31].…”

Electrochemically Fabricated Polypyrrole–Cobalt–Oxygen Coordination Complex as High‐Performance Lithium‐Storage Materials

“…Figure 4 compares the Raman spectra of the as-prepared Co 3 O 4 /PPy composite and the composite after different elec- www.chemeurj.org trochemical processes. Most of the Raman bands of PPy disappear or become very weak after the composite is initially discharged to 0.0 V. The Raman shift of the C=C backbone stretching mode [13,14] decreases from 1579 cm À1 in the as-prepared composite to 1557 cm À1 in the discharged sample, implying the increase of the conjugation length (or decrease of the strength) of the C=C bond. Meanwhile, no traces of cobalt oxides can be recognized in the discharged or recharged composite.…”