Micro Emulsion Synthesis of LaCoO₃Nanoparticles and their Electrochemical Catalytic Activity

Abstract

The micro emulsion method has been successfully used for preparing perovskite LaCoO 3 with uniform, fine-shaped nanoparticles showing high activity as electro catalysts in oxygen reduction reactions (ORRs). They are, therefore, promising candidates for the air-cathode in metal-air rechargeable batteries. Since the activity of a catalyst is highly dependent on its specific surface area, nanoparticles of the perovskite catalyst are desirable for catalyzing both oxygen reduction and evolution reactions. Herein, LaCoO 3 powder was also prepared by sol-gel method for comparison, with a broad particle distribution and high agglomeration. The electro catalytic properties of LaCoO 3 and LaCoO 3 -carbon Super P mixture layers toward the ORR were studied comparatively using the rotating disk electrode technique in 0.1 M KOH electrolyte to elucidate the effect of carbon Super P. Koutecky-Levich theory was applied to acquire the overall electron transfer number (n) during the ORR, calculated to be ~3.74 for the LaCoO 3 -Super P mixture, quite close to the theoretical value (4.0), and 2.7 for carbon-free LaCoO 3 . A synergistic effect toward the ORR is observed when carbon is present in the LaCoO 3 layer. Carbon is assumed to be more than an additive, enhancing the electronic conductivity of the oxide catalyst. It is suggested that ORRs, catalyzed by the LaCoO 3 -Super P mixture, are dominated by a 2+2-electron transfer pathway to form the final, hydroxyl ion product.

Facile Fabrication of Novel Hetero-Structured Organic–Inorganic High-Performance Nanocatalyst: A Smart System for Enhanced Catalytic Activity toward Ciprofloxacin Degradation and Oxygen Reduction

“…In order to investigate the kinetics of ORR on the electrode surface, linear sweep voltametry (LSV) of Ag 2 MoO 4 and the composite were performed, and with increasing the rotation speed, the limiting current density was observed to be increased for both the materials as expected. Figure a represents the LSV plots of Ag 2 MoO 4 in O 2 saturated 1 M KOH solution with onset potential 0.60 V and cathodic current density of 3.7988 mAcm –2 at a potential 0.2 V vs RHE at 1925 rpm whereas, the composite exhibits a positive shift of 90 mV in onset potential having onset potential 0.69 V and corresponding current density 4.8789 mAcm –2 at a potential of 0.2 V (Figure c), which is better than the reported literature value . Moreover, for the composite, the limiting current density was found to be higher than pure Ag 2 MoO 4 for each rotational speed.…”

Combining in situ electrochemistry, operando XRD & Raman spectroscopy, and density functional theory to investigate the fundamentals of Li2CO3 formation in supercapacitors

“…[59][60][61] and O 2 (ref. [62][63][64] onto carbon-based electrodes (graphene, graphite, glassy carbon, and pyrolytic carbon). The Li 2 -SO 4 $H 2 O and Li 2 CO 3 bands observed using operando Raman spectroscopy and not under XRD analysis are related to the design of the coin cell onto the sample-holder (electrode exposed surface) and the ux of the incident beam.…”

“…Even without NiO nanoparticles, it was expected H 2 (ref [59][60][61]. and O 2 (ref [62][63][64]. onto carbon-based electrodes (graphene, graphite, glassy carbon, and pyrolytic carbon).…”

Enhancing Interaction between Lanthanum Manganese Cobalt Oxide and Carbon Black through Different Approaches for Primary Zn–Air Batteries

“…There is a wide variety of carbon materials that can be combined with perovskitetype metal oxides, which have demonstrated an improvement in electrocatalytic activity. Carbon black (CB) materials are the most commonly used because they increase the electrical conductivity and even exhibit some inherent ORR activity (some examples are Vulcan XC-72(R) [25][26][27], acetylene black [28,29], Ketjen black [30], and Super P [31,32]). Several studies have explored incorporating carbon materials with even higher electrical conductivity, such as carbon nanotubes [33,34] and graphene-based materials [35,36], or higher surface areas like activated carbons [37].…”