Spectroscopic Insights into the Influence of Filling Carbon Nanotubes with Atomic Nanowires for Photophysical and Photochemical Applications

Abstract

Studying the optical performance of carbon nanotubes (CNTs) filled with guest materials can reveal the fundamental photochemical nature of ultrathin one-dimensional (1D) nanosystems, which are attractive for applications including photocatalysis. Here, we report comprehensive spectroscopic studies of how infiltrated HgTe nanowires (NWs) alter the optical properties of small-diameter (d t < 1 nm) single-walled carbon nanotubes (SWCNTs) in different environments: isolated in solution, suspended in a gelatin matrix, and heavily bundled in network-like thin films. Temperature-dependent Raman and photoluminescence measurements revealed that the HgTe NW filling can alter the stiffness of SWCNTs and therefore modify their vibrational and optical modes. Results from optical absorption and X-ray photoelectron spectroscopy demonstrated that the semiconducting HgTe NWs did not provide substantial charge transfer to or from the SWCNTs. Transient absorption spectroscopy further highlighted that the fillinginduced nanotube distortion can alter the temporal evolution of excitons and their transient spectra. In contrast to previous studies on functionalized CNTs, where electronic or chemical doping often drove changes to the optical spectra, we highlight structural distortion as playing an important role.

Single Quasi-1D Chains of Sb2Se3 Encapsulated Within Carbon Nanotubes

“…S9). 57,62 To systematically validate the shifts that we observed, multiple spots of thinly dispersed sample on a 300 nm SiO2/Si substrate were sampled. These thin films of Sb2Se3@CNT enabled the observation of the Raman-active modes of the underlying substrate alongside the Sb2Se3@CNT peaks.…”

“…This strategy has been historically demonstrated to reliably harbor metastable 1D phases that would not exist without the stabilization of the nanotube with many competing phases. 21,[53][54][55][56][57][58][59][60][61][62][63][64][65][66] Throughout this manuscript, these heterostructures will be denoted as "material@CNT". This system allows for long-range order and atomic precision of the guest structures within the host nanotubes due to the inert vdW surface of CNTs which would be the ideal conditions to isolate the single chains of 1D and q-1D vdW crystals to form vdW-vdW interfaces.…”

Single Quasi-1D Chains of Sb2Se3 Encapsulated within Carbon Nanotubes

“…To this end, encapsulation routes within nanotubes such as single or multiwalled carbon nanotubes (CNTs) or boron nitride nanotubes have been employed to isolate well-defined, precise nanowires (Figure F). This strategy has been demonstrated to harbor metastable 1D phases that would not exist without the stabilization of the nanotube with many competing phases. − Throughout this article, these heterostructures will be denoted as “ material@CNT ” by convention. This system allows for long-range order and atomic precision of the guest structures within the host nanotubes due to the inert vdW surface of CNTs which would be the ideal conditions to isolate the single chains of 1D and q-1D vdW crystals to form vdW–vdW interfaces.…”

“…Encouragingly, encapsulation within CNTs has also been used to isolate 1D vdW transition metal trichalcogenides (TMTs) with weak interchain vdW interactions such as NbSe 3 and HfTe 3 into single covalent chains and to stabilize novel TMT metastable phases not accessible through the bulk phase such as NbTe 3 , VTe 3 , and TiTe 3 . , A key enabling factor in stabilizing these structures is the inert vdW environment within the CNT host, which protects the guest structures from ambient air- or chemically induced degradation. As such, encapsulation within CNTs has also been used to access the formation of atomically precise nanoribbon-like monolayer structures, zigzag strips, and even helical chains derived from 2D vdW crystals by protecting the in-plane dangling bonds from oxidation in ambient conditions. ,,, Enabled by the atomic precision of the guest structures inside CNTs, these heterostructures have been used as a reliable platform to investigate the evolution of the photophysics, , electron transport, magnetic interactions, and electron–phonon coupling upon encapsulation of a library of guest structures. ,, We aimed to employ this synthetic strategy to isolate single chains of our model q-1D vdW phase, Sb 2 Se 3 , and use the resulting heterostructure to probe the evolution of the structural attributes and photophysical properties of Sb 2 Se 3 upon encapsulation.…”

“…As such, encapsulation within CNTs has also been used to access the formation of atomically precise nanoribbon-like monolayer structures, zigzag strips, and even helical chains derived from 2D vdW crystals by protecting the in-plane dangling bonds from oxidation in ambient conditions. 56 , 58 , 60 , 67 Enabled by the atomic precision of the guest structures inside CNTs, these heterostructures have been used as a reliable platform to investigate the evolution of the photophysics, 57 , 58 electron transport, 65 magnetic interactions, 68 and electron–phonon coupling 56 upon encapsulation of a library of guest structures. 19 , 56 , 68 We aimed to employ this synthetic strategy to isolate single chains of our model q-1D vdW phase, Sb 2 Se 3 , and use the resulting heterostructure to probe the evolution of the structural attributes and photophysical properties of Sb 2 Se 3 upon encapsulation.…”