Single wall carbon nanotube (SWCNT)/Si heterojunction photodetectors have the advantages of high photoresponse ability and simple structure, however, their detection wavelength range are usually lower than 1100 nm, which limits their application in the infrared band. We report a SWCNT/Cu/Si photodetector with both a high photoresponse and a detection range up to the infrared band by depositing a Cu nanoparticles (NPs) layer between a SWCNT film and a n-Si substrate. It was found that the Cu NPs produce strong surface plasmon resonance (SPR) under laser irradiation, which breaks through the limitation of Si band gap and greatly improves the photoresponse of the SWCNT/Cu/Si photodetector in the near infrared band. The responsivity (R) of the photodetector in the wavelength range of 1850–1200 nm reached 2.2–14.15 mA/W, which is the highest value in the reported plasmon enhanced n-Si based photodetectors, and about 20,000 times higher than that of a SWCNT/Si photodetector. Its R value for 1550 nm wavelength used in optical communications reached ~ 8.2 mA/W, which is 64% higher than the previously reported values of commonly used photodetectors. We attribute the significant increase to the strong SPR and low Schottky barrier of Cu with n-Si, which facilitates the generation and transfer of the carriers.

Carbon nanotube (CNT) fibers have great promise for constructing multifunctional fabrics with high electrical conductivity, good electro-heating ability, excellent flexibility, and a low density. However, the inter-fiber contacts in the fabric greatly reduce these advantages and limit their application. Herein, a simple pressure-fusing method to fabricate single-wall CNT (SWCNT) fiber non-woven fabrics (NWFs) that are composed of interconnected SWCNT fibers with fused joints is reported, which have good flexibility, a low density of 0.46 g/cm³, a high electrical conductivity of 3.7 × 10⁵ S/m, and a record high specific electrical conductivity of 803 (S·m²)/kg. They also showed excellent electrical heating ability, so that a temperature of ~ 160 °C was rapidly reached at a low voltage of 2 V. Combined with their low density, the SWCNT fiber NWFs are promising for use as a heating unit for low temperature battery protection and de-icing applications.

The efficient recovery of gold from industrial sewage is important for saving precious metals and remains a big challenge. We report the extraction of gold ions from a trace-level aqueous solution using a tannic acid (TA) coated single-wall carbon nanotube (SWCNT) film. The TA has many redox ligands that efficiently adsorb Au(III) from the solution and reduce them to Au particles. The interwoven SWCNTs not only act as a framework to improve the mechanical stability of the hybrid membrane, but also provide abundant paths for H₂O transport, and facilitate the full exposure of the TA. As a result, the hybrid membrane has an excellent ability to capture gold ions from solution with a high flux of 157 L/(m²·h·bar), and an ultra-high adsorption capacity of 2095 mg/g from solutions with an extremely low gold concentration of 20 ppm. The adsorbed gold ions are reduced to Au particles, which can be easily collected by oxidation. The recovered Au nanoparticles on the TA–SWCNT hybrid film had a remarkable surface-enhanced Raman scattering effect that enabled the sensitive detection of rhodamine 6G.