Facile one-pot synthesis of low cost MnO2 nanosheet/Super P Li composites with high oxygen reduction reaction activity for Zn-air batteries

Efficient Modulation of Electron Pathways by Constructing a MnO2–x@CeO2 Interface toward Advanced Lithium–Oxygen Batteries

“…The O 1s spectrum showed three types of oxygen peaks at 532.9, 531.4, and 529.6 eV (Figure b), corresponding to O surf , O ads , and O lat , respectively. − O surf indicates the surface adsorption of hydroxide or water, O ads is assigned to the oxygen vacancy, which can adsorb O 2 in the air to generate low-coordination oxygen ion species, while O lat is ascribed to the lattice oxide oxygen. After the introduction of CeO 2 , the relative content of O ads increases, demonstrating that the affinity to O 2 may be enhanced because O ads is the index related to the oxygen vacancy, which is beneficial to the ORR process. , Figure c shows the high-resolution XPS spectrum of Mn 2p; the peaks at 654.0 and 642.3 eV correspond to Mn 2p 1/2 and Mn 2p 3/2 , respectively. − The peaks of Mn 2p 1/2 and Mn 2p 3/2 for PCS/MnO 2– x @CeO 2 negatively shifted about 0.6 and 0.8 eV compared with that for PCS/MnO 2– x , respectively, indicating that the self-driven electrons were transferred from CeO 2 to MnO 2– x through the interface. The Ce 3d high-resolution XPS spectrum of PCS/MnO 2– x @CeO 2 shows the hybridization of Ce 4+ , Ce 3+ and shake-up peaks in the sample (Figure d). − The porous structure was further revealed by nitrogen adsorption–desorption isotherm measurements.…”

“…With the increasing demand for sustainable development due to the energy crisis, the search for novel and clean renewable energy has become an important strategic task. − Li–O 2 batteries are considered an ideal power source due to their advantages of high theoretical energy density (3500 Wh kg –1 ). − However, despite great promise, there are still many critical problems, mainly caused by the insulation and insolubility of the discharge product Li 2 O 2 , which is difficult to be decomposed during charging, leading to a high overpotential, short cycle life, and limited practical application of the battery. − To overcome this problem, efforts have been made to explore efficient and robust cathode catalysts, including precious metals, transition-metal oxides, etc. , Among numerous materials, manganese dioxide (MnO 2 ) is considered a very promising candidate and has aroused extensive attention due to various advantages, − such as the tunability of the crystal and electronic structures resulting from the multiple valence states of MnO 2 and the intrinsically remarkable oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity. − Although significant progress has been made in utilizing various crystals of MnO 2 with controlled morphology, particle size, and porosity, further improvement of the ORR/OER catalytic activity from these aspects is generally far from satisfactory. Constructing a hybrid MnO 2 -based catalyst with other suitable components to meet the requirements for higher ORR/OER performance is a feasible approach.…”

Boosting the activity and stabilityviasynergistic catalysis of Co nanoparticles and MoC to construct a bifunctional electrocatalyst for high-performance and long-life rechargeable zinc–air batteries

“…[13][14][15][16] Currently, various advanced and low-cost non-precious metal-based electrocatalysts are being designed and developed. [17][18][19][20][21] Among these are nitrogen-doped carbon (NC) materials with transition metal nanoparticles as the main active sites. 22,23 Owing to the satisfactory inherent benefits of catalysts like outstanding conductivity of electrons, abundant active sites, and excellent activity, NC materials are considered promising electrocatalysts for OER or ORR processes.…”

Facile Synthesis of MnO2/MWCNTs via UV Photolysis as High-Performance and Low-Cost Cathodes for Aqueous Magnesium Ion Batteries

“…Yan et al synthesized an Al x MnO 2 cathode from manganese oxide via electrochemical transformation, which displayed a high voltage plateau (1.6 V) and a specific capacity of 460 mA h g –1 for over 80 cycles in the aqueous Al-ion battery . Among various phases, birnessite-type MnO 2 (δ-MnO 2 ) composed of edge-sharing MnO 6 octahedra subunits possesses layer structures with an interlayer spacing of about 0.73 nm, which show the rapid migration of interlayer cations and avoid the structural rearrangement. − Kim et al used spinel Mn 3 O 4 as a cathode material in the MgSO 4 electrolyte for the phase transition and electrochemical behavior during the charge–discharge process . The result demonstrated that the partial dissolution of Mn 2+ and oxidation of Mn 3+ to Mn 4+ led to the formation of layer MnO 2 from spinel Mn 3 O 4 during initial several cycles, which displayed a specific capacity of 220.1 mA h g –1 at 50 mA g –1 .…”