Nanostructured manganese oxides exhibit facet-dependent oxidation capabilities. Issue 12 (19th November 2020)

• Record Type: Journal Article
• Authors: Fu, Di; Duan, Lin; Jiang, Chuanjia; Zhang, Tong; Chen, Wei
• Is Part Of: Environmental science. Volume 7:Issue 12(2020)
• Page Start: 3840
• Page End: 3848
• Publication Date: 2020-11-19
• Subjects: Environmental sciences -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d0en00958j
• Languages: English
• ISSNs: 2051-8153

Abstract

Abstract : Nanostructured manganese oxides exhibit facet-dependent capabilities that can be exploited to improve their performance for sustainable agricultural application. Abstract : Applying nanostructured manganese oxides (nano-MnO x ) in contaminated agricultural lands offers the coupled benefits of oxidizing a range of environmental contaminants while simultaneously releasing micronutrients ( i.e., dissolved Mn 2+ ) that are vital for crop growth. However, little is known about how the key nanocrystal properties affect the oxidation capabilities of nano-MnO x . Here, we show that an α-MnO2 nanostructure with predominantly exposed {100} facets (referred to as α-MnO2 -100) exhibits greater oxidation capability for bisphenol A (BPA, a model pollutant commonly found in agricultural lands) than an α-MnO2 nanostructure with predominantly exposed {310} facets (α-MnO2 -310), while consistently releasing a greater amount of Mn 2+ . Fitting the reaction kinetics data using a retarded rate model shows that α-MnO2 -100 possesses more reactive sites with higher reactivity. Density functional theory (DFT) calculations show that the {100} facet possesses a higher density of binding sites and the complexation of BPA molecules on the facet is thermodynamically more favorable, mainly due to its specific surface topography. Moreover, ligand-promoted Mn(iii ) release experiments and X-ray photoelectron spectroscopy analysis verify that α-MnO2 -100 contains a greater abundance of surface Mn(iii ), a more effective electron acceptor than Mn(iv ). The findings suggest that facet engineering can be exploited to improve the performance of nano-MnO x for sustainable agricultural applications.