Enhanced Catalytic Activity of Non-platinum Catalyst for Oxygen Reduction in Alkaline Solution

Abstract

Remarkable enhancement in catalytic activity of a non-platinum catalyst for oxygen reduction in alkaline solutions has been achieved by an oxidative pretreatment of a high-area carbon support before dispersion of catalyst precursor (cobalt hexacyanoferrate), followed by pyrolyzing the precursor under an inert atmosphere. The polarization potential for oxygen reduction at substantial current densities at room temperature under air was higher than a potential corresponding to a limit of relative predominance for O2/HO2− couple.

Peroxide Elimination Activity of Heat-Treated Transition Metal Hexacyanoferrate Catalysts for Oxygen Reduction in Alkaline Solution

“…Further enhanced performance of the air cathode with the present nonprecious metal catalysts is possible by attaining high dispersion of the catalyst on a high-area carbon support, as reported previously. 21 A concern about the catalyst is stability. After soaking the catalyst HT͑800͒-Co͓Fe͔PB/C in 0.25 M KOH solution for a week at room temperature, no deterioration in the electrode performance was recognized.…”

“…The advantage of using such inorganic precursor is that a series of compounds consisting of various combinations of transition metal ions located at nitrogen-coordinated and carboncoordinated sites can be easily prepared from popular transition metal salts, so that an effect of combination of transition elements upon the catalytic activity for oxygen reduction is effectively examined. Such an advantage has worked out well to find that the combination of cobalt and iron gives the prominent synergistic effect on the catalytic activity for oxygen reduction, [19][20][21] and that the catalyst containing copper and iron shows very low generation of hydrogen peroxide during oxygen reduction. 22,23 Oxygen reduction is known to proceed typically through the two pathways.…”

“…[1][2][3][15][16][17] Recently, we have reported highly active, nonprecious metal catalysts prepared from the inorganic precursors based on abundant 3d transition elements. [18][19][20][21][22][23] The catalysts were prepared by heattreating the nitrogen-containing inorganic compounds ͑transition metal hexacyanometallates, Prussian blue analogs, PBs͒ dispersed on carbon black. The advantage of using such inorganic precursor is that a series of compounds consisting of various combinations of transition metal ions located at nitrogen-coordinated and carboncoordinated sites can be easily prepared from popular transition metal salts, so that an effect of combination of transition elements upon the catalytic activity for oxygen reduction is effectively examined.…”

Pyrolyzed cobalt hexacyanocobaltate dispersed on reduced-graphene-oxide as an electrocatalyst of the oxygen reduction reaction in an alkaline medium

“…18,51 A cobalt-substituted PB analogue, cobalt hexacyanoferrate, immobilized on carbon black (Vulcan XC-72) was previously used aer heat treatment by Sawai et al to enhance the ORR. 52,53 To our best knowledge, there was no attempt so far to utilize well-dened cyanocobaltate polynuclear network as a source of unique and distinct cobalt centers for ORR. In the present study, reduced graphene oxide (rGO) has been selected as the support because of its potential to improve efficiency of the electron transport as well as the recognized utility as a carrier for immobilization and distribution of catalytic nanocenters.…”

Platinum-free Air Cathode Catalyst for Metal/Air Batteries

“…For efficient reduction of oxygen at low and moderate temperatures, many efforts have been made to develop platinum-free catalysts, such as transition metal oxides (4)(5)(6), transition metal macrocycles (7)(8)(9), and alternative catalysts (10)(11)(12). Recently, highly active Pt-free catalysts prepared from inorganic precursors dispersed on carbon black have been reported (13)(14)(15)(16)(17)(18). The catalysts were prepared from the nitrogen-and carbon-containing inorganic precursors (transition metal hexacyanometallates, Prussian blue analogs) dispersed on carbon black.…”