Mn₅O₈ Nanoparticles as Efficient Water Oxidation Catalysts at Neutral pH

Abstract

Mn5O8 nanoparticles (NPs) were obtained via the controlled oxidation of MnO NPs. The oxygen evolution reaction (OER) properties of Mn5O8 NPs were evaluated using cyclic voltammetry (CV). A current density of 5 mA/cm2 was reached when 580 mV of overpotential was applied at pH 7.8. Electron paramagnetic resonance (EPR) analysis was conducted to investigate the origin of high OER activity of Mn5O8 NPs. From the EPR analysis, Mn3+ was found to be involved in the OER process of the Mn5O8 materials.

Self‐Standing CoP Nanosheets Array: A Three‐Dimensional Bifunctional Catalyst Electrode for Overall Water Splitting in both Neutral and Alkaline Media

“…And it needs overpotential of only 320 and 536 mV to drive 2 and 10 mA cm −2 at neutral pH, respectively, which is much smaller than that of α‐Co(OH) 2 NA/CC ( =420 mV, =640 mV) in the OER process. This overpotential compares favorably to the behavior of other reported catalysts like 1‐D CoHCF/CFP ( =∼490 mV), Mn 5 O 8 NPs ( =500 mV), Co 3 S 4 nanosheets ( =520 mV), and ZrS 3 nanosheets ( =510 mV) under neutral condition, implying the high OER activity of CoP NA/CC. It is important to point out that the CC substrate has poor activities for HER and OER, confirming that CoP NA/CC is dominantly responsible for the HER and OER electrocatalysis.…”

Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

“…Therefore, the DFT calculations directly support the experimental observation of high overpotential (>0.6 V) towards HER and OER for the hydroxylated Mn 5 O 8 . It was recently reported that Mn 5 O 8 nanoparticles showed very good OER activity in a neutral electrolyte in the presence of Mn 3+ species29. Further studies will be needed to elucidate the influence of Mn valences, such as Mn 3+ (from Mn 3 O 4 or Mn 2 O 3 phase) or Mn 2+ /Mn 4+ (from Mn 5 O 8 ), on the gas evolution reactions.…”

Unveiling the active sites of graphene-catalyzed peroxymonosulfate activation

“…Generally, the catalytic properties of metalbased catalysts are very sensitive to the size and shape of the metal crystal, due to the specifically exposed crystal facets and ill-defined surface with edges, corners exhibit better excess and lower binding energy for adsorption with the reactants [4]. Meanwhile, the transition metal oxides possess variable valent states, different types of bridging or terminal lattice oxygen, and oxygen vacancies, which play vital roles in interacting with the reactants especially in a redox process [5][6][7]. Distinctly, it has been widely accepted that pristine carbocatalysis might be originated from the "active sites'' such as structure defects, functional groups, or heteroatom-doping induced modulations to the carbon network, which usually exhibit characteristic electronic states and spin cultures.…”