Ultrafine IrO2 nanoparticle-decorated carbon as an electrocatalyst for rechargeable Li–O2 batteries with enhanced charge performance and cyclability

Abstract

Ultrafine iridium (IV) oxide (IrO 2 ) nanoparticles are homogeneously distributed on the surface of porous Ketjenblack (KB) carbon (IrO 2 /KB) via one-step hydrothermal approach, and the resulting nanocomposite is investigated as an electrocatalyst for nonaqueous Li-O 2 batteries. Transmission electron microscopy confirms the high dispersion of ultrafine IrO 2 particles with an average particle size of 1.47 nm. The IrO 2 /KB electrode exhibits remarkable catalytic activity towards oxygen evolution reaction (OER) as indicated by the voltammetric measurements. And, the IrO 2 /KB electrode decreases the recharge overpotential by ca. 400 and 200 mV compared to the electrodes with pure KB and a mechanical mixture of KB and pre-synthesized IrO 2 , respectively. Li-O 2 battery with IrO 2 /KB achieves high-capacity retention and stable cyclability, maintaining a long cycle life for 70 cycles without sharp decay under a limited dischargecharge depth of 500 mAh g −1 (ca. 1100 mAh g C −1). X-ray diffraction and scanning electron microscope analysis reveal that this excellent rechargeability is based on the reversible formation and decomposition of toroid-shaped lithium peroxide. Therefore, the uniform distribution of ultrafine IrO 2 particles, with extraordinary OER catalytic activity, on KB carbon enables the IrO 2 /KB to be a promising electrocatalyst for Li-O 2 batteries.

Doped reduced graphene oxide mounted with IrO2 nanoparticles shows significantly enhanced performance as a cathode catalyst for Li-O2 batteries

“…Both capacity and capacity retention are much higher than the battery without IrO 2 mounting, indicating the significant enhancement of the iridium oxide. Furthermore, our results are actually much better than those of batteries with noble metal-based catalysts as the cathode, reported by other groups previously [20,29]. to what other recent studies have reported [30,31].…”

“…In most situations, pure carbon materials have poor OER activity, so creating composite catalysts by introducing suitable OER catalysts into graphene can be quite effective [14][15][16]. IrO 2 , recognized as the best catalyst for the OER, is widely used for fuel cell and water electrolysis [17,18] [20]. The ORR activity of IrO 2 and the dispersion of IrO 2 nanoparticles are problematic, but we can use a carbon material to make up for this deficiency, and graphene is ideal.…”

IrO2 Surface Complexions Identified through Machine Learning and Surface Investigations

“…The theoretical predictions are supported by surface investigations of IrO 2 single crystals, which exhibit (101) facets rather than the more common low-energy (110) orientation of rutile [23,24]. Characterization by low-energy electron diffraction (LEED), scanning-tunneling microscopy (STM), and x-ray photoelectron spectroscopy (XPS) confirms the properties of the predicted metal-rich complexions, explaining why IrO 2 nanoparticles often expose (101) facets [25][26][27][28][29][30][31].…”

“…[22,23] Characterization by low-energy electron diffraction (LEED), scanning-tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) confirms the properties of the predicted metal-rich complexions, explaining why IrO2 nanoparticles often expose (101) facets. [24][25][26][27][28][29][30] Our investigation starts with the creation of a reference database of DFT structures to train the non-parametric GAP potential. GAPs decompose the total energy of a system into a sum of atomic energies that depend on the local chemical environment.…”

Facet‐Dependent Oxygen Reduction Reaction Activity on the Surfaces of Co3O4

“…Consequently, the development of the nonprecious catalysts such as transition‐metal oxides, metal nitrides, and carbon‐based materials is essential in replacing the Pt‐based noble‐metal catalyst. [ 6‐9 ] The Co 3 O 4 shows adaptive activity for ORR and has further potential applications in the Li‐O 2 battery. [ 10‐12 ] But it is still inferior to precious catalysts because of the limited active sites and sluggish kinetics of Co 3 O 4 .…”