Chromium-Decorated Double-Walled Carbon Nanotubes for Preferential Room-Temperature Xylene Sensing
- 1Department of Physics and Astronomy, Botswana International University of Science and Technology, Boseja Ward, Palapye Private Bag 16, Botswana.
- 2Université de Toulouse, Toulouse INP, CNRS, CIRIMAT, Toulouse, France.
Abstract
Room-temperature discrimination of closely related aromatic volatile organic compounds remains challenging for chemiresistive sensors. Here, chromium-modified double-walled carbon nanotubes (Cr-DWNTs) were prepared using an endohedral filling process and were investigated for preferential xylene detection. X-ray diffraction showed substantial transformation of the CrCl2 precursor to rhombohedral Cr2O3 identified as the dominant crystalline chromium-containing phase. Transmission electron microscopy and elemental analysis supported association of the chromium-containing phase with the DWNT structure. Raman spectroscopy showed retention of the characteristic D, G, and 2D bands with only a small change in the ID/IG ratio, indicating preservation of the graphitic framework after chromium modification. Hall-effect measurements showed positive Hall coefficients for both pristine DWNTs and Cr-DWNTs, confirming hole-dominated transport, while Cr-DWNTs exhibited a lower apparent Hall carrier concentration together with substantially higher carrier mobility and conductivity. Cr-DWNTs exhibited a pronounced preferential response toward xylene over 0.1–10 ppm. The xylene response increased from approximately 0.96% at 0.1 ppm to 5.93% at 10 ppm and was enhanced by approximately 1.9–2.6 times relative to pristine DWNTs. Within 0.1–1 ppm, the low-concentration xylene sensitivity was 2.36 % ppm−1 (R2=0.958), with a calculated limit of detection of approximately 37 ppb. The enhanced response is attributed to the combination of the intrinsic affinity of graphitic carbon toward methyl-substituted aromatics and interfacial electronic transduction within the DWNT network. These results demonstrate that chromium modification provides an effective strategy for amplifying room-temperature xylene selectivity in CNT-based chemiresistive sensors.
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BibTeX
@article{setlhare2026chromiumdecorated,
title = {{Chromium-Decorated Double-Walled Carbon Nanotubes for Preferential Room-Temperature Xylene Sensing}},
author = {Tlotlo Cassandra Setlhare and Atlang Gild Mpolokang and Emmanuel Flahaut and Martin Figueiredo and George Chimowa},
journal = {Materials},
year = {2026},
month = oct,
doi = {10.3390/ma19204378},
url = {https://hal.science/hal-05835665v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Chromium-Decorated Double-Walled Carbon Nanotubes for Preferential Room-Temperature Xylene Sensing
AU - Tlotlo Cassandra Setlhare
AU - Atlang Gild Mpolokang
AU - Emmanuel Flahaut
AU - Martin Figueiredo
AU - George Chimowa
PY - 2026
DA - 2026/10/18
JO - Materials
DO - 10.3390/ma19204378
UR - https://hal.science/hal-05835665v1
AB - Room-temperature discrimination of closely related aromatic volatile organic compounds remains challenging for chemiresistive sensors. Here, chromium-modified double-walled carbon nanotubes (Cr-DWNTs) were prepared using an endohedral filling process and were investigated for preferential xylene detection. X-ray diffraction showed substantial transformation of the CrCl2 precursor to rhombohedral Cr2O3 identified as the dominant crystalline chromium-containing phase. Transmission electron microscopy and elemental analysis supported association of the chromium-containing phase with the DWNT structure. Raman spectroscopy showed retention of the characteristic D, G, and 2D bands with only a small change in the ID/IG ratio, indicating preservation of the graphitic framework after chromium modification. Hall-effect measurements showed positive Hall coefficients for both pristine DWNTs and Cr-DWNTs, confirming hole-dominated transport, while Cr-DWNTs exhibited a lower apparent Hall carrier concentration together with substantially higher carrier mobility and conductivity. Cr-DWNTs exhibited a pronounced preferential response toward xylene over 0.1–10 ppm. The xylene response increased from approximately 0.96% at 0.1 ppm to 5.93% at 10 ppm and was enhanced by approximately 1.9–2.6 times relative to pristine DWNTs. Within 0.1–1 ppm, the low-concentration xylene sensitivity was 2.36 % ppm−1 (R2=0.958), with a calculated limit of detection of approximately 37 ppb. The enhanced response is attributed to the combination of the intrinsic affinity of graphitic carbon toward methyl-substituted aromatics and interfacial electronic transduction within the DWNT network. These results demonstrate that chromium modification provides an effective strategy for amplifying room-temperature xylene selectivity in CNT-based chemiresistive sensors.
SN - 1996-1944
ER -