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Rechargeable sodium-ion batteries (SIBs) have received significant attention as a promising alternative to traditional lithium-ion counterparts for large-scale energy storage applications owing to the low cost and abundance of sodium resources. Herein, we demonstrate the photonic irradiated mesoporous reduced graphene oxide (rGO)-TiO2 nanocomposite architectures using environmentally benign, ultrafast split-second (millisecond) intense pulsed light (IPL) process at room temperature. The photonic IPL irradiation spontaneously triggers the deoxygenation of graphene oxide (GO) and the simultaneous structural engineering of TiO2 nanocomposites. The precisely controlled IPL irradiation (energy density of 10 J cm−2) exhibits excellent conductivity, high surface area, and outstanding electrochemical performance as a green anode material for SIBs. The photonic IPL irradiated rGO-TiO2 nanocomposite delivers a high reversible capacity of 244 mAh g−1 at 0.1 Ag-1, a high rate performance of 112 mAh g−1 at 1 Ag-1, and high cycling stability compared to pristine GO-TiO2 and conventional furnace annealed rGO-TiO2 (FH-rGO-TiO2) nanocomposites. The detailed electrochemical analysis suggests that the improved capacitance contribution results from the fast kinetics of the IPL irradiated rGO-TiO2 nanocomposite anode. This work provides new insight into the fabrication of versatile, cost-effective techniques for developing advanced electrode materials for energy applications.

Achieving a highly active cathode surface with extremely efficient electrocatalysts for oxygen reduction kinetics is a fundamental necessity for durable fuel cells. Developing such active materials into desirable nanostructures is crucial in the pursuit of electrocatalysis. A facile preparation of cobalt decorated nitrogen and sulfur co-doped carbon nanostructures (Co–NSC) with the added advantage of Zeolitic imidazolate frameworks (ZIF), ZIF 67@ZIF 8 is reported here. The as-prepared Co, N, S, co-doped carbon (Co–NSC) electrocatalyst comes under platinum group metal-free (PGM-free) catalysts which intends to replace the scarce and highly expensive commercial Pt catalysts. Facile preparation of the Co–NSC catalyst that is scalable, low cost and highly ORR active makes the material advantageous. Co–doping sulfur has dramatically enhanced the intrinsic catalytic activity of the catalyst, and the degree of variation in sulfurization greatly influences the overall catalytic property. Co–NSC 200 with high sulfur doping exhibit a positively shifted onset potential of 0.81 V, and a high yielding current density of 5.5 mA cm−2 at 20 mV s−1.

Producing low–cost non–precious metal catalysts in large scales to be used as air–cathodes for efficient oxygen reduction and evolution reactions in Li–O2 batteries is a demanding task. Herein, we report a simple technique for the synthesis of a carbide composite comprising molybdenum and tungsten with a robust nanowire structure. When applied as an air–cathode electrocatalyst in Li–O2 batteries, the nanowire composite delivered high specific discharge capacity with reversibility and cyclability. This work provides a novel approach for tailoring nano–architectures and thereby achieving high–power Li–air batteries.

The choice of electrolyte solvent is expected to play a key role in influencing the lithium-oxygen battery performance. The electrochemical performances of three electrolytes composed of lithium bis (trifluoromethane sulfonyl) imide (LiTFSI) salt and different solvents namely, ethylene carbonate/propylene carbonate (EC/PC), tetra ethylene glycol dimethyl ether (TEGDME) and dimethyl sulfoxide (DMSO) are investigated by assembling lithium oxygen cells. The electrolyte composition significantly varied the specific capacity of the battery. The choice of electrolyte also influences the overpotential, cycle life, and rechargeability of the battery. Electrochemical impedance spectra, cyclic voltammetry, and chronoamperometry were utilized to determine the reversible reactions associated with the air cathode.

Iron phthalocyanine supported on graphite nanofibers (GNF_FePc) were synthesized using a simple solvothermal process and characterized using various structural analyses. GNF_FePc were employed as bifunctional electrocatalysts in the air cathode of lithium-oxygen batteries. Galvanostatic charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy were performed to assess the Performance of Li-air batteries. The air-cell delivered a high specific capacity of ∼5500 mAh/g at the first cycle which remained close to 90% of that value after 4 cycles. The reversibility was nearly 100% for all the four cycles with comparatively lower over potential.

We have synthesized three dimensional architectural α–MnO2/RuO2 hybrid nanostructures with three different compositions of (75:25), (69:31) and (50:50) by hydrothermal approach and evaluated their bifunctional electrocatalytic activity for Li–O2 battery applications. The morphology of the α–MnO2/RuO2 nanostructures changed from sharp sea urchins to solid nanospheres with increasing RuO2 content in the composition. The variations observed in physical, structural, morphological and electrochemical properties were characterized with respect to the MnO2/RuO2 concentrations by step by step analyses. MnO2 exhibited better ORR catalytic activity, while RuO2 revealed superior OER catalytic activity. Among the concentrations investigated, α–MnO2:RuO2 (75:25) exhibited superior catalytic activity for oxygen reduction and evolution reactions in aqueous media. This excellent catalytic activity logically led us to apply it as air-cathode catalyst in Li–O2 cell, which produced a maximum capacity of >8100 mAh g−1 with high columbic efficiency and cyclability. The superior performance of the hybrid nanostructure is mainly attributed to its structural and compositional design which favors the electrochemical activity. Based on a careful investigation on the structural characterizations, the growth mechanism of the 3D nanostructured α–MnO2/RuO2 mixed oxides is discussed in detail.

The graphene/cubic cobaltite oxide nanosheets (rGO/Co 3 O 4 ) with a face centered cubic crystalline structure are synthesized and are exploited as effective cathode catalysts in high performance Lithium-air batteries. The morphological images enunciate that 220 nm average diameter of Co 3 O 4 nanosheets are effectively anchored over the graphene sheets and the diameter of individual nanoparticles that construct the cubic nanosheets is 5 nm. The growth and composite formation mechanisms of prepared nanostructures are identified from Raman and FT-IR spectroscopic techniques. rGO/Co 3 O 4 composite exhibits a lower voltage, high discharge capacity of 4150 mAh g −1 and displays superior cyclability without any capacity losses, signifying the excellent rechargeability of the fabricated electrodes. The post mortem analysis of electrodes specify the existence of lithium peroxide (Li 2 O 2 ), lithium oxide (Li 2 O) and lithium carbonate (Li 2 CO 3 ) discharge products, revealing the involved electrochemical reaction of Lithium-air batteries. The excellent electrochemical properties of rGO/Co 3 O 4 composite is due to the combination of rapid electrokinetics of electron transport and high electrocatalytic activity toward oxygen reduction reaction given via the synergetic effects of rGO and cubic Co 3 O 4 nanosheets. These findings provide fundamental knowledge on understanding the influence of morphological and structural properties of graphene based nanostructures toward Lithium-air battery performances.

The high performance of α–MnO2/NGNF catalyzed air cathode for Li–O2 battery is reported in this article. The α–MnO2 nanorods are successfully grown on highly conductive nitrogen doped graphite nanofibers with caterpillar like morphology by a simple hydrothermal technique. The as–prepared α–MnO2/N–GNF catalyst exhibits better electrocatalytic performance in terms of oxygen reduction and evolution reactions in the air cathode exhibiting comparatively low overpotential. In addition to the low overpotential, α–MnO2/NGNF catalyzed Li–O2 battery also show high capacity, reversibility and rate capability. The combined effect of α–MnO2 and N–GNF for facilitating electrochemical reactions between Li and O2 is described for improving energy and columbic efficiency of Li–O2 battery.

The metal-based catalysts have been playing a major role in various industrial processes, whereas carbon based nanomaterials have recently been demonstrated to be promising metal-free alternatives for low cost catalytic processes. The doping of nitrogen in carbon and the electrocatalytic properties of the nitrogen doped carbon for oxygen reduction reactions are investigated in this article. We propose a simple method for doping nitrogen in various carbon materials like carbon black and ketjen black, and comparatively studied their physical and electrochemical characteristics. Raman and XPS analyses show significant peak shifts of their characteristic peaks caused by nitrogen doping on the surface of carbon materials. N-doped carbons show higher surface area in Brunauer, Emmett and Teller surface area analysis and more porous structure than undoped carbons in scanning electron microscope images. The N-doped sample was also ball milled to study the surface properties. All samples, i.e. undoped, N-doped and N-doped ball-milled carbons were compared for electrocatalytic activity by cyclic voltammetry and oxygen reduction reaction measurements. Nitrogen doped carbons exhibit better electrocatalytic activity with high mass activity and positive shift of peak potential than undoped samples with electron transfer number of 3.6 close to that of commercial Pt/C.

The single step hydrothermal synthesis of well-dispersed cobalto-cobaltic oxide (Co3O4) cubic nanocrystals has been reported. Microstructure and phase have been unambiguously characterized by XRD, TEM and Raman spectroscopy. Powder X-ray diffraction (XRD) and Raman spectrum showed that the as-prepared sample was of cubic spinel structure. Transmission electron microscopy indicated that the Co3O4 nanocrystals were cubical with the crystallite size in the range of 20–30 nm. Since the particle size of the powdered samples were found to be equivalent from both TEM and X-ray diffraction technique, it can be expected that the nanocubes are single crystalline. The average BET surface area was found to be 75 m2 g− 1 and the average pore diameter was found to be 15 nm.