Mixed Redox-Couple-Involved Chalcopyrite Phase CuFeS2 Quantum Dots for Highly Efficient Cr(VI) Removal

• Published in: Environmental science & technology Vol. 54; no. 13; pp. 8022 - 8031
• Main Authors: Ge, Qiuyue, Feng, Xuezhen, Wang, Ranhao, Zheng, Renji, Luo, Siyuan, Duan, Lele, Ji, Yongfei, Lin, Jia, Chen, Hong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07-07-2020
• Subjects: Adsorption; Aqueous solutions; Cations; Chalcopyrite; Chemists; Chromium; Contaminants in Aquatic and Terrestrial Environments; Copper; Crystal structure; Histograms; Iron; Nanomaterials; Nanotechnology; Quantum confinement; Quantum dots
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.0c01018

Iron-based nanosized ecomaterials for efficient Cr­(VI) removal are of great interest to environmental chemists. Herein, inspired by the “mixed redox-couple” cations involved in the crystal structure and the quantum confinement effects resulting from the particle size, a novel type of iron-based ecomaterial, semiconducting chalcopyrite quantum dots (QDs), was developed and used for Cr­(VI) removal. A high removal capacity up to 720 mg/g was achieved under optimal pH conditions, which is superior to those of the state-of-the-art nanomaterials for Cr­(VI) removal. The mechanism of Cr­(VI) removal was elucidated down to an atomic scale by combining comprehensive characterization techniques with adsorption kinetic experiments and DFT calculations. The experimental results revealed that the material was a good electron donor semiconductor attributed to the existence of “mixed redox couple of Cu­(I)-S-Fe­(III)” in the crystal structure. With the size-dependent quantum confinement effect and the high surface area, the semiconducting chalcopyrite QDs could effectively remove Cr­(VI) from aqueous solution through a syngenetic photocatalytic reduction and adsorption mechanism. This study not only reports the design histogram of the iron-based CuFeS2 QD ecomaterial for efficient Cr­(VI) removal but also paves the way for understanding the atomic-scale mechanism behind the syngenetic effects of using the QD semiconducting material for Cr­(VI) removal.