Dual Role of Silver Moieties Coupled with Ordered Mesoporous Cobalt Oxide towards Electrocatalytic Oxygen Evolution Reaction

Abstract

Herein, we show that the performance of mesostructured cobalt oxide electrocatalyst for oxygen evolution reaction (OER) can be significantly enhanced by coupling of silver species. Various analysis techniques including pair distribution function and Rietveld refinement, X‐ray absorption spectroscopy at synchrotron as well as advanced electron microscopy revealed that silver exists as metallic Ag particles and well‐dispersed Ag2O nanoclusters within the mesostructure. The benefits of this synergy are twofold for OER: highly conductive metallic Ag improves the charge transfer ability of the electrocatalysts while ultra‐small Ag2O clusters provide the centers that can uptake Fe impurities from KOH electrolyte and boost the catalytic efficiency of Co–Ag oxides. The current density of mesostructured Co3O4 at 1.7 VRHE is increased from 102 to 211 mA cm−2 with incorporation of silver spices. This work presents the dual role of silver moieties and demonstrates a simple method to increase the OER activity of Co3O4.

Principles of Water Electrolysis and Recent Progress in Cobalt‐, Nickel‐, and Iron‐Based Oxides for the Oxygen Evolution Reaction

“…Although cobalt oxide is a decent OER catalyst it suffers from its low conductivity. Its conductivity can be improved by merging with more conductive materials like graphitic carbon, [99] gold, [100] and silver [101] . Recently, we have shown the dual functions of Ag species when they are coupled with mesoporous cobalt oxide [101] .…”

TunableegOrbital Occupancy in Heusler Compounds for Oxygen Evolution Reaction**

“…Here, we selected Co 2 ‐based Heusler compounds (Co 2 Mn Z ), i.e., Co 2 MnAl, Co 2 MnTi, Co 2 MnGa, and Co 2 MnV, with different N v and e g filling, for OER study. It is not only due to the fact that Co as a 3d metal possesses varying e g electron configuration with introducing different neighboring atoms, but also because of the high OER activity that Co‐based catalysts have shown in the previous study [15–18] . All the compounds were first synthesized by arc‐melting method into bulk crystals (Figure S1), which can be later cut into desired shapes [2] .…”

Large‐Scale Production of Carbon‐Supported Cobalt‐Based Functional Nanoparticles for Oxygen Evolution Reaction

“…[10] In this regard, Co is a promising element to replace rare noble metals such as Pt and Ir as catalysts for the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) in fuel cells, [11][12][13][14] and the hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) in electrolyzers. [15][16][17][18][19][20][21] These catalytic processes benefit from conductive carbon supports that are crucial to achieve sufficient charge transport in the composite material for better performance. Consequently, for the above-mentioned electrochemical reactions, the carbonaceous support should stabilize the Cobased nanoparticles, provide a high specific surface area for the catalytically active component, and improve the electrical conductivity of the composite material.…”