δ-MnO₂ with an ultrahigh Mn⁴⁺ fraction is highly active and stable for catalytic wet air oxidation of phenol under mild conditions

Abstract

The self-reactivated δ-MnO2 catalyst was developed, and showed high activity and stability for the CWAO of phenol at a very low temperature.

Boosted Charge Transfer in Twinborn α-(Mn2O3–MnO2) Heterostructures: Toward High-Rate and Ultralong-Life Zinc-Ion Batteries

“…The XRD pattern of the α-(Mn 2 O 3 @MnO 2 ) precursor exhibits predominantly an amorphous phase without any calcination, which is similar to the crystallized α-MnO 2 with indistinct patterns. When the α-(Mn 2 O 3 @MnO 2 ) precursor is annealed at 400 °C, the stronger peaks of α-(Mn 2 O 3 @MnO 2 )-400 clearly emerge at 2θ = 18.05, 28.6, 36.36, 37.47, 41.9, 49.73, and 59.9, − corresponding to the XRD standard of tetragonal α-MnO 2 (JCPDS, 44-0141, 14/m). Annealing at 450 °C facilitates the further growth of the phase of α-MnO 2 as well as the appearance of the α-Mn 2 O 3 phase (JCPDS, 41-1442) with the peaks of α-Mn 2 O 3 at 2θ = 23.13, 32.95, 38.23, 45.12, 49.31, 55.18, and 60.05° in α-(Mn 2 O 3 @MnO 2 )-450 .…”

Investigation into the Phase–Activity Relationship of MnO2 Nanomaterials toward Ozone‐Assisted Catalytic Oxidation of Toluene

“…Peaks with binding energies of near 642.0 and 643.5 eV in the XPS spectra of Mn 2p 3/2 of the MnO 2 samples ( Figure ) can be assigned to Mn 3+ and Mn 4+ , respectively. [ 38–40 ] It is noteworthy that the binding energies of these peaks are slightly different for different MnO 2 samples. This result indicates that crystal phase has a certain effect on the electron density of the MnO 2 surface, which is related to the degree of charge imbalance, oxygen vacancies, as well as the relative content of Mn 3+ and Mn 4+ .…”

Activation of O2 over three-dimensional manganese oxide nanoprisms under ambient conditions towards oxidative removal of aqueous organics

“…Catalytic wet air oxidation (CWAO) has emerged as an efficient process for activation of O 2 and then degradation of organic contaminants with high concentration. [27][28][29][30][31][32] However, harsh conditions, such as high temperatures (∼100 °C) and pressures (∼5 MPa), are generally required for realizing a good removal efficiency, which leads to high cost and investment. [33][34][35][36] In recent years, activation of O 2 over advanced catalytic materials under ambient conditions has been developed for the degradation of aqueous emerging contaminants and persistent organic pollutants.…”