Adsorption of Molecular Gases on Silver/Carbon Nanotube Composites at Low Temperatures and Low Pressures

Abstract

We present an experimental study adsorption of molecular gases (N2, H2, O2, CH4, C2H4, and C2H6) on multiwalled carbon nanotubes (MWCNTs) and MWCNT doped with Ag at low temperatures (35 K) and pressures (10−6 Torr) using the temperature programmed desorption technique. Our results show that the desorption kinetics is of the first order; furthermore comparative measurements indicate that Ag/MWCNTs have an adsorption capacity higher than that of a pure sample suggesting that these composites are good candidates as gas cryosorbers for applications in cryopumps or sensor of latest generation.

CO2 adsorption on silver nanoparticle/carbon nanotube nanocomposites: A study of adsorption characteristics

“…Moreover, the first‐order behavior indicates the only interaction between gas molecules and substrates, without gas–gas relations on the sample surface. Furthermore, the value of the desorption temperature (less than 120 K), as demonstrated in our previous work , is associated with adsorption energy less than this required for chemisorptions (>50 kJ/mol).…”

“…We deposited a drop of solution on a copper substrate for morphological analysis. The MWCNTs appear in SEM images as bundles with an average diameter of 30 nm and a length that ranges from 5 to 20 μm, more details on CNTs are in our previous papers .…”

“…The experiments were conducted in an ultrahigh vacuum chamber (base pressure in the low 10 −9 Torr range) evacuated by a dry turbo pump (more information about experimental setup is in Ref. ). The gas (N 2 , O 2 , and CO 2 with a purity of 99.999%) was introduced in the chamber through a precision leak valve, while keeping the sample at an adsorption temperature of T ad = 30 K and at a fixed pressure of 1 × 10 −6 Torr (measured at room temperature and corrected for the ion gauge sensitivity factor), for a chosen time interval (gas doses were measured in Langmuir, 1 L = 1 × 10 −6 Torr/s).…”

Study on the adsorption of 2,4-dichlorophenoxyacetic acid on carbon nanotube by means of density functional theory

“…Để tăng tương tác giữa 2,4-D với ống CNT, ống CNT ban đầu được biến tính bằng cách pha tạp các nguyên tử kim loại (Fe hoặc Ag) lên bề mặt. Các kim loại Fe, Ag được lựa chọn để tính toán do một số nghiên cứu thực nghiệm đã chỉ ra việc pha tạp các nguyên tố này có khả năng làm tăng khả năng hấp phụ của CNT [24,25]. Sự hình thành các hệ M-CNT từ M (M= Fe, Ag) và CNT có thể được mô tả bằng sơ đồ sau: M + CNT → M-CNT Quá trình này được đặc trưng bởi giá trị năng lượng tương tác -Eint, được xác định theo công thức: q(M), e 0,312 0,286 BO (M-CNT) 1,589 0,177 Các giá trị Eint tương đối âm, cho thấy quá trình biến tính CNT bằng các nguyên tử Fe hoặc Ag là hoàn toàn thuận lợi về mặt năng lượng.…”