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Start Over Author "Hu, Xinjun" Publisher elsevier bv
34 results on '"Hu, Xinjun"'

20. Oxidation mechanism of the arsenopyrite surface by oxygen with and without water: Experimental and theoretical analysis

Author

Zhou Xinjun, Liu Dian-wen, Chen Manjiao, Tian Jianping, Wang Jingsong, Hu Xinjun, Zhou Xian, Wan Rundong, Zhang Zhengfu, and Shen PeiLun

Subjects
inorganic chemicals, Arsenopyrite, Chemistry, Inorganic chemistry, General Physics and Astronomy, chemistry.chemical_element, Surfaces and Interfaces, General Chemistry, Condensed Matter Physics, Redox, Oxygen, Dissociation (chemistry), Surfaces, Coatings and Films, Chemical state, Adsorption, Desorption, visual_art, visual_art.visual_art_medium, Molecule
Abstract

Arsenopyrite is a common mineral that is abundant in nonferrous metal tailings. Study of the atomic configuration, chemical state, and morphology of the oxidation products of the arsenopyrite surface is important for enhancing the resource utilization and environmental safety of cementitious backfill. In this paper, the chemical states of the surface atoms of arsenopyrite oxidized with and without water were analyzed by X-ray photoelectron spectroscopy (XPS). The (0 0 1) surface oxidation process of arsenopyrite by oxygen with and without water was characterized using density functional theory (DFT). Results of the XPS analysis showed that water molecules participated in the oxidation reaction and formed a large number of OH structures on the surface of arsenopyrite; the relative content of Sn2−, As(III), and Fe(II) increased significantly. The DFT calculations revealed that oxygen molecules are more easily adsorbed on the As2-Fe2 site by chemical adsorption (Fe2 is the second ortho Fe atom of As2), and water molecules are adsorbed on the Fe2 site by physical adsorption. The oxidation process of the (0 0 1) surface by oxygen can be divided into four stages: adsorption, dissociation, bridging oxygen formation, and desorption of oxidation products; the As2 atom with three coordination sites on the surface of (0 0 1) is oxidized first. In the presence of water, the water molecule dissociates into OH and H, resulting in the hydroxylation of As and Fe atoms on the (0 0 1) surface. Calculation of the energy difference and reaction energy barrier between different reaction steps showed that the participation of water molecules reduces the reaction energy barrier and increases the reaction energy. The oxidation products are derived from the arsenic oxidation of (AsO2) and (HAsO2) types without and with water, and (HAsO2) is easily desorbed from the surface. Water molecules accelerate the surface oxidation of arsenopyrite and cause the surface to form hydroxylated oxidation products.

Published
2022

26. Rapid and facile synthesis of graphene quantum dots with high antioxidant activity

Author

Ma Xiaoyan, Jianping Tian, Hu Xinjun, and Huang Zhixiong

Subjects
Antioxidant, Biocompatibility, DPPH, Graphene, Radical, medicine.medical_treatment, Oxide, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Redox, Combinatorial chemistry, 0104 chemical sciences, law.invention, Inorganic Chemistry, chemistry.chemical_compound, chemistry, law, Quantum dot, Materials Chemistry, medicine, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract

Graphene quantum dots (GQDs) are one of most promising antioxidants owing to their fascinating properties, including favorable biocompatibility, high antioxidant activity, and low toxicity. In this work, an efficient and rapid approach for preparing GQDs was developed. The graphene oxide (GO) sheet was thoroughly fragmented into the GQDs by the hydroxyl radicals (OH•) generated from a O3/H2O2/UV oxidation reaction. GQDs possessed a large content of sp2-hybridized carbon domains and abundant functional groups in edge. The 1,1-diphenyl-2-picryl-hydrazyl (DPPH•) radical scavenging method and dye decoloration test were used to investigate the antioxidant activity of GQDs, which exhibited high antioxidant activity and great application prospects for corrosion protection, medicinal uses, and the antioxidation of organic dyes.

Published
2020

27. Brønsted acid catalyzed proto-functionalization of enecarbamates and enamides: A convenient route to N,O-acetals

Author

Zou Wei, Hu Xinjun, Li Yanli, Ma Xiao-Yan, and Zhang Chang-Fei

Subjects
010405 organic chemistry, Chemistry, Organic Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, Nucleophile, Drug Discovery, Functional group, Surface modification, Organic chemistry, Brønsted–Lowry acid–base theory
Abstract

N,O-acetals are important structures found in many bioactive natural products, and this unique organic functional group can serve as a useful synthetic precursor to the unstable N-acylimines. In this paper, a convenient route to synthesize N-carbamoyl-N,O-acetals and N-acyl-N,O-acetals from enecarbamates and enamides in the presence of alcohols as the solvents and nucleophile sources under Bronsted acid conditions was reported. This strategy could be used to prepare various N,O-acetals from a range of enecarbamates and enamides with light alcohols, and the products are obtained in good yields (52–98%).

Published
2020

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