The laccase-like reactivity of manganese oxide nanomaterials for pollutant conversion: rate analysis and cyclic voltammetry

Abstract

Nanostructured manganese oxides, e.g. MnO2, have shown laccase-like catalytic activities, and are thus promising for pollutant oxidation in wastewater treatment. We have systematically compared the laccase-like reactivity of manganese oxide nanomaterials of different crystallinity, including α-, β-, γ-, δ-, and ɛ-MnO2, and Mn3O4, with 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 17β-estradiol (E2) as the probing substrates. The reaction rate behaviors were examined with regard to substrate oxidation and oxygen reduction to evaluate the laccase-like catalysis of the materials, among which γ-MnO2 exhibits the best performance. Cyclic voltammetry (CV) was employed to assess the six MnOx nanomaterials, and the results correlate well with their laccase-like catalytic activities. The findings help understand the mechanisms of and the factors controlling the laccase-like reactivity of different manganese oxides nanomaterials, and provide a basis for future design and application of MnOx-based catalysts.

Synthesis, Catalytic Properties and Application in Biosensorics of Nanozymes and Electronanocatalysts: A Review

“…ABTS oxidation by γ-MnO 2 NPs under different pH values proved high oxidation activity of γ-MnO 2 at pH values of 3-4. The findings add to the understanding of the laccase-like catalysts based on MnOx [270].…”

“…Nanomaterials that do not contain copper could also possess laccase mimicking activity. Many metal-based catalysts have been described recently, including noble metal NPs: gold [266], platinum [267], or oxides such as iron oxide [12,17], cerium(IV) oxide [268,269], manganese oxide [270], etc. Huang and coauthors [264] described a laccase-mimic NZ based on copper ions and adenosine monophosphate (AMP-CuNZ) with a 15-fold higher catalytic activity than that of natural laccase (at the same mass concentration; normalization to the molar concentration of both catalysts for calculating k cat was not reported).…”

“…Nanomaterials that do not contain copper could also possess laccase mimicking activity. Many metal-based catalysts have been described recently, including noble metal NPs: gold [266], platinum [267], or oxides such as iron oxide [12,17], cerium(IV) oxide [268,269], manganese oxide [270], etc.…”

“…Wang and coworkers [270] proposed different crystalline nanostructured manganese oxide (MnO 2 ) and Mn 3 O 4 on an electrode surface, which showed laccase-like catalytic activity toward ABTS and 17β-estradiol (E2). The best catalytic performance of the six different crystal structures for oxidizing ABTS and E2 was shown for the γ-MnO 2 variant.…”

Facile synthesis of laccase mimic Cu/H3BTC MOF for efficient dye degradation and detection of phenolic pollutants

“…17,18 Due to unstable nature and low yield of laccase, different approaches have been reported to develop laccase-like materials. [19][20][21][22][23][24][25][26] But their laccase activity was not good enough compare to natural enzymes and still highly desirable to be studied due to wide range of applications.…”