Co/Mo bimetallic addition to electrolytic manganese dioxide for oxygen generation in acid medium

Abstract

An efficient electrocatalyst comprising inexpensive and earth-abundant materials for the oxygen evolution reaction (OER) is crucial for the development of water electrolysis. In this work, in-situ addition of cobalt/molybdenum ions to the electrolytic manganese dioxide has been shown to be beneficial for the OER in acid solution as its overpotential performed better (305 mV) than that of the commercial DSA® (341 mV) at 100 mA cm−2. The OER was investigated at ambient temperature in 2 M H2SO4 solution on the modified EMD (MnMoCoO) electrodes. The energy efficiency of the MnMoCoO electrodes improved significantly with the amount of Co in the plating solution. For the electrodeposited catalysts, physico-chemical and electrochemical measurements were conducted including static overpotentials. The better performance of the modified EMD was attributed to an improved charge transfer resistance (Rct; 0.290 Ω cm2), average roughness factor (rf; 429) and decrease in water content in the electrodeposited catalysts. The kinetic parameters obtained on MnMoCoO catalysts were compared and discussed according to the cobalt concentration.

Recent Development of Oxygen Evolution Electrocatalysts in Acidic Environment

“…For this purpose, numerous research groups have been working on the development of transition metal oxides for OER in acid. [192][193][194][195][196][197][198][199][200][201][202][203][204] Mn-based oxides and Cobased oxides are the two most widely investigated transition metal oxides. First, Mn-based oxides are considered for OER in acid due to the nature of self-healing to compensate their dissolution in acid.…”

“…First, Mn‐based oxides are considered for OER in acid due to the nature of self‐healing to compensate their dissolution in acid. [ 192 ] Up to now, numerous Mn‐based oxides have been fabricated and optimized, such as TiO 2 ‐incorporated MnO 2 , [ 138 ] hausmannite‐like intermediate (α‐Mn 3 O 4 ), [ 193 ] MnO 2 with metastable Mn 3+ , [ 194 ] Co/Mo‐doped MnO 2 (MnMoCoO), [ 195 ] Cu 1.5 Mn 1.5 O 4 :10F, [ 196 ] Ni x Mn 1− x Sb 1.6–1.8 O y , [ 197 ] (Mn 0.9 Nb 0.1 )O 2 :10F, [ 198 ] NiPbO x , [ 199 ] etc. Among these Mn‐based oxides, the well‐designed gamma manganese oxides (γ‐MnO 2 ) showed a long‐term stability of 8000 h between 1.6 and 1.75 V versus RHE (at 10 mA cm −2 ) in a pH = 2 electrolyte.…”

A Porous Cobalt (II) Metal–Organic Framework with Highly Efficient Electrocatalytic Activity for the Oxygen Evolution Reaction

“…However, both are made of precious metals which render them unsuitable for use in largescale practical applications. Therefore, substantial research effort has been devoted to explore non-noble metal catalysts with high electrocatalytic activity and stability, such as 3d-transition-metal oxides, perovskites, transition-metal sulfides, hydro(oxy)oxides, phosphates, non-metal compounds and molybdates, along with various molecular catalysts [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Among these well-developed electrocatalysts, 3d-transition metal compounds, especially cobalt-based compounds, have attracted growing research interests and have exhibited high electrocatalytic activity for OER due to their various redox properties and unusual capability to form high-oxidation cobalt species during OER process [ 27 , 28 ].…”

Earth-Abundant Electrocatalysts in Proton Exchange Membrane Electrolyzers

“…It should be noted though that the loading of the EAC was 6.7 times higher than for IrO2. Another Mn-based electrocatalyst was a Mo-and Co-modified electrolytic manganese dioxide (MEMD) developed by Delgado et al [201]. According to the authors, Mo was incorporated in EMD for improvement of its mechanical stability, while the role of Co was to reduce the water content in EMD and increase the electrical conductivity.…”