Effectiveness of phase- and morphology-controlled MnO₂ nanomaterials derived from flower-like δ-MnO₂ as alternative cathode catalyst in microbial fuel cells

Abstract

Crystal phase and morphology variations obtained by simple high-temperature annealing offer promising strategies for employing nanostructured manganese oxide as a cathode catalyst for microbial fuel cells (MFCs).

δ-MnO2 Nanoflowers and Their Reduced Graphene Oxide Nanocomposites for Electromagnetic Interference Shielding

“…Recently, manganese dioxide (MnO 2 ) attracted much attention in basic scientific research due to its natural abundance, nontoxicity, environmental compatibility, low-cost, thermal stability, high specific surface area, easy synthesis, and its potential technological applications . MnO 2 exists as α, β, γ, and δ polymorphs depending on the different linkages of subunits of MnO 6 octahedra. − The unique and distinct properties of MnO 2 are attributed to the tunnels/layers present in these crystallographic forms. , Among these, δ-MnO 2 was reported to be a potential material for multifaceted applications. ,, The most bottom-up synthesis processes of δ-MnO 2 involved chemical reduction or hydrothermal processes. , A δ-MnO 2 nanoflower has been prepared from an aqueous solution of KMnO 4 and MnSO 4 ·H 2 O under hydrothermal conditions at 160 °C for 24 h . In another method, δ-MnO 2 particles have been prepared by the reduction of KMnO 4 by ascorbic acid (pH = 3 and 5) in an ice-water bath .…”

“…Li et al, prepared flowerlike tubular δ-MnO 2 nanostructures by the microwave-assisted hydrothermal method. Alternatively, δ-MnO 2 has also been fabricated by oxidation of Mn 2+ , ,, reduction of MnO 4 – , a redox reaction between Mn 2+ and Mn 4+ , , thermal decomposition, the hydrothermal method with KMnO 4 as the only raw material, sol–gel, KMnO 4 reacting with acidified water, the hydrothermal microwave-assisted hydrothermal method involving decomposition of KMnO 4 in acidic conditions, and by direct phase transition from manganese oxides. , …”

Binder-Free α-MnO2 Nanowires on Carbon Cloth as Cathode Material for Zinc-Ion Batteries

“…Different cathode materials have been employed for ZIBs, e.g., Prussian blue analogues [26][27][28], vanadium-based oxides [29,30], and manganese-based oxides (MnO x ) [31]. For a long time, MnO x has been a subject of intensive research due to its numerous potential applications in different electrochemical energy storage and conversion devices, such as fuel cells, supercapacitors, and batteries [32][33][34][35]. Manganese oxide (MnO 2 ) is also considered a potential electrode for ZIBs [36][37][38].…”

Interrelationships between the structural, spectroscopic, and antibacterial properties of nanoscale (< 50 nm) cerium oxides

“…Nanoparticles exhibiting pore diameters in the 2–50 nm range are considered mesoporous in nature 61 . The adsorption–desorption isotherms illustrate type-IV isotherm curves with H3-type hysteresis loops, which are characteristics of mesoporous structured nanoparticles containing slit-like pores 62 , 63 . The pore diameters increase, while the BJH pore volumes decrease for nanoparticles calcined at high temperatures, as shown in Table 2 .…”