Enhanced Tunneling in a Hybrid of Single-Walled Carbon Nanotubes and Graphene

Abstract

Transparent and conductive films (TCFs) are of great technological importance.The high transmittance, electrical conductivity and mechanical strength make singlewalled carbon nanotubes (SWCNTs) a good candidate for their raw material. Despite the ballistic transport in individual SWCNTs, however, the electrical conductivity of their networks is limited by low efficiency of charge tunneling between the tube elements. Here, we demonstrate that the nanotube network sheet resistance at high optical transmittance is decreased by more than 50% when fabricated on graphene and thus provides a comparable improvement as widely adopted gold chloride (AuCl 3 ) 1 arXiv:1903.06449v1 [physics.app-ph] 15 Mar 2019 doping. However, while Raman spectroscopy reveals substantial changes in spectral features of doped nanotubes, no similar effect is observed in presence of graphene.Instead, temperature dependent transport measurements indicate that graphene substrate reduces the tunneling barrier heights while its parallel conductivity contribution is almost negligible. Finally, we show that combining the graphene substrate and AuCl 3 doping, the SWCNT thin films can exhibit sheet resistance as low as 36 Ω/ at 90% transmittance.The electrical transport in networks of single-walled carbon nanotubes (SWCNTs) vary in a wide range of values as the structure of tubes and the morphology of networks differ.Since the modest conductivity reported in the seminal demonstrations, 1,2 the performance has gradually improved through morphological optimization 3-9 and progress in non-covalent doping. 5,10-12 Meanwhile, as confirmed by numerous direct measurements, 13-15 the limiting

Local probe investigation of electrocatalytic activity

“…189 Even though carbon nanotubes are generally acknowledged for their high conductivity, their resistance can further be decreased by more than 50% if they form hybrids with graphene, due to enhanced effectiveness of charge tunneling. 190 Lately, such a hybrid electrocatalyst based on graphene nano-akes (GFs) and carbon nanotubes (CNTs) doped with heteroatoms such as N, Co and Mo (N-Co-Mo-GF/CNT) was studied for its ORR and OER activity by Tavakkoli et al 51 The OER catalytic activity was investigated by means of SECM in SG/TC mode in alkaline media on two different substrates, namely nickel (Ni) and glassy carbon (GC). When GC was used, the tip response (increase of ORR current) was almost simultaneous with the oxygen generation (OER onset potential), compared to the Ni substrate in which case the tip response was delayed (Fig.…”

Tight-binding investigation of the structural and vibrational properties of graphene–single wall carbon nanotube junctions

“…the y-direction) to avoid any interaction with spurious replica images. Out of the wide range of available chiralities, CNT (5,5), (6,6), (7,7), (8,8), (9,9), (10,10) and (11,11) for forming the systems of armchair SWNT-SLG and CNT(8,0), CNT(10,0), CNT(13,0) and CNT(16,0) for making the systems of zigzag SWNT-SLG were chosen.…”

“…Nano-sized carbon allotropes, specially single-walled carbon nanotubes (SWNTs) and single-layer graphene (SLG), are the most widely studied materials due to their extraordinary mechanical, chemical and optical properties [1][2][3][4][5][6] and their exceptional electronic transport makes them a suitable substitute for active layers in future nanoelectronic devices. [7][8][9][10] Devices based on the hybrid system, combining SWNTs and SLG, have shown great potential in terms of electrical conductivity 11 and mechanical strength, 12 and also have found applications in various elds, such as transparent conducting electrodes, 13,14 active layers in TFTs, 15 humidity and gas sensors, 16 biomedical applications, 17 next generation aromatic compound adsorbents, 18 etc. To improve and tune the desired properties for advanced applications such as transparent electrodes and active layers in TFTs, it is very important to understand the structure of SWNT-SLG junction at the atomic scale and various interactions between the two, which modify the properties of the hybrid nanostructures.…”

Hybrid Films Based on Bilayer Graphene and Single-Walled Carbon Nanotubes: Simulation of Atomic Structure and Study of Electrically Conductive Properties

“…Based on the results of DFT calculations performed for an atomistic model comprising one armchair and two zigzag semiconducting nanotubes, it was shown that the addition of graphene flakes introduced additional electronic states at the Fermi level, which increased the current and conductivity of graphene/SWCNT hybrid system [ 30 ]. In turn, it was experimentally revealed that when a SWCNT film is deposited on a graphene substrate, its conductivity increases by approximately the same amount as in chemical doping due to a decrease in the height of the tunnel barrier inside the carbon material [ 31 ]. At the same time, the issues of controlling the conductive properties of graphene/SWCNT hybrid structures by choosing a certain topology of nanotubes and graphene, as well as their mutual orientation in the hybrid architecture, remain poorly understood.…”