BET theory

About: BET theory is a research topic. Over the lifetime, 9046 publications have been published within this topic receiving 286142 citations.

Bone char-derived metal-free N- and S-co-doped nanoporous carbon and its efficient electrocatalytic activity for hydrazine oxidation

Abstract: Bone char (BC) was successfully used, for the first time, both as a self-template/a pore-former and a precursor of heteroatoms (N and S atoms) during carbonization of sucrose, allowing for the synthesis of nanoporous N- and S-co-doped carbon (NSC) material possessing high surface area and excellent electrocatalytic activity. BC’s ability to help with the formation of nanopores in the carbon material was indirectly confirmed by making a control material, denoted as pyrolyzed sucrose or PS, under the same condition but without including BC in the reaction media. N2 gas porosimetry showed that NSC had a very large BET surface area (1108 m2 g−1), which is about 60% higher than that of PS (443 m2 g−1). Comparison of the SEM images of the two materials also indicated some differences in their textural and morphological features. XPS analysis showed that NSC had a higher content of S (2.29%) than PS (0.21%) and that the S atoms were distributed mostly in the form of thiophenic moieties (32.3% for the PS and 59.2% for the NSC). Although some of the S groups were originated from sulfuric acid, which was used for the dehydration of sucrose during the synthesis of the materials, this result indicated that BC was the major source of the S dopant atoms in NSC as well as the major reason for the formation of thiophenic groups in this material. Furthermore, while PS’s structure did not have N dopants, NSC’s lattice had about 1.39% of N dopant atoms that existed in the form of pyridinic, pyrrolic and graphitic groups and that were also originated from BC. X-ray diffraction and Raman spectroscopy revealed that NSC’s lattice had a higher density of defects than PS. Owing to its high surface area and optimal density of heteroatom dopant groups and defect sites, NSC exhibited excellent electrocatalytic activity toward the hydrazine oxidation reaction (HzOR), or the lowest overpotential ever reported for this reaction, along with a high current density. Besides making it among the most efficient electrocatalysts for HzOR, its electrocatalytic performance can make this metal-free material a good alternative to the conventional metal-based electrocatalysts that are commonly used in HzOR-based fuel cells.

A Visible Light-Driven Titanium Dioxide Photocatalyst Codoped with Lanthanum and Iodine: An Application in the Degradation of Oxalic Acid

Abstract: A series of photocatalysts was synthesized by codoping TiO2 with lanthanum and iodine (La−I−TiO2). The structure and properties of the catalysts were studied by X-ray diffraction (XRD), the Brunauer−Emmett−Teller (BET) method, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV−vis diffuse reflectance spectra. The prepared anatase-phase La−I−TiO2 (molar ratio 20:20:100) calcined at 400 °C had a BET surface area of 92.9 m2 g−1, and the crystallite size calculated from XRD data was ∼3.57 nm, and it had a remarkable absorption in the visible light range of 400−550 nm. The catalytic efficiency was tested by monitoring the photocatalytic degradation of oxalic acid under visible light irradiation. An optimum molar ratio of 20:100 La/TiO2 was determined for the most efficient inhibition of the recombination of electron−hole pairs and the photocatalytic activity of La−I−TiO2 calcined at 400 °C was significantly higher than that calcined at 500 or 600 °C in aqueous oxalic acid so...