Cobalt Oxide Materials for Oxygen Evolution Catalysis via Single‐Source Precursor Chemistry

Abstract

The utilization of metal alkoxides as single-source precursors for (mixed-)oxide materials offers remarkable benefits, such as the possibility to precisely control the metal ratio in the resulting material, highly homogeneous distribution of the elements in the film, and the low temperatures required for film processing. Herein we report on the isolation and characterization of the bimetallic Co-Mo alkoxide [Co Mo O (OCH ) (dmf) ] (Co Mo ; dmf=N,N-dimethylformamide), which was prepared by the anion metathesis reaction of the corresponding metal chlorides. The Co-Mo alkoxide was explored as a well-defined precursor of cobalt oxide catalysts for the oxygen evolution reaction (OER) in alkaline electrolyte MOH. The catalysts demonstrated excellent activity in the OER, manifested in low onset potentials and Tafel slopes and superb stability under the operating conditions both in alkaline and nearly neutral media. It was observed that the nature of the metal cation of the alkaline electrolyte MOH (M =Li , Na , K , Cs ) greatly affected the catalytic performance of the material. We propose that the positive effect of larger metal cations on the film activity in the OER could be explained by the higher hydration enthalpies of larger ions and enhanced mass transport within a larger interlayer space between the [CoO ] sheets of the in situ formed binary oxides. It may be deduced that this trend is universal and may be extended to other types of metal oxides forming layered structures during the OER.

Hierarchical Cu(OH)2@Co(OH)2 Nanotrees for Water Oxidation Electrolysis

“…3d transition metals and related materials have been intensively investigated as efficient electrocatalysts because of abundant resources and particular electronic configuration. [8][9][10][11][12][13][14][15][16][17] Among these promising catalysts, earthabundant Cu and Co based materials are highly desired for oxygen evolution reaction (OER). [18][19][20] For example, Kuznetsov et al and Tong et al fabricated bimetallic CoÀ Mo alkoxides and oxygen-deficient Co 3 O 4 quantum dots as efficient electrocatalysts to enhance the oxygen evolution electrolysis.…”

“…[18][19][20] For example, Kuznetsov et al and Tong et al fabricated bimetallic CoÀ Mo alkoxides and oxygen-deficient Co 3 O 4 quantum dots as efficient electrocatalysts to enhance the oxygen evolution electrolysis. [13,14] Cao et al reported on the investigation of CuÀ Ni sulfide nanowires for improving water oxidation efficiency. [21] Chen et al investigated CuÀ Co(OH) 2 nanosheets having superior electrocatalytic activity with an OER overpotential of 300 mV at 10 mA cm À 2 .…”

New Avenues to Chemical Space for Energy Materials by the Molecular Precursor Approach

“…The drop‐casted precursor decomposed at an applied positive potential where Mo was completely lost from the films giving rise to high surface area films identified as cobalt oxo‐hydroxide. [ 93 ] Spiccia and his group received similar results for their electrodeposited [Ni(en) 3 ]Cl 2 (en = 1,2‐diaminoethane) precursor to form a NiO x ‐en film from a 0.10 m borate buffer (NaBi) solution (pH = 9.2). The NiO x ‐en films were more homogenous and had a higher electroactive surface area than films prepared from a simple Ni nitrate precursor, leading to more robust films with higher catalytic activity underlining the importance of the choice of molecular precursors.…”

Modulating electronic and geometric structure of transition metal compounds for efficient water splitting

“…Recently, 3d transition metal and their compounds are intensively investigated as efficient electrocatalysts due to their rich source and special d electronic configuration. 46,54,55,60,61,64,[157][158][159] Among all these promising catalysts, earth-abundant Cu and Co based materials are highly desired for OER. For example, Kuznetsov et al and Tong et al fabricated bimetallic Co-Mo alkoxide and oxygen-deficient Co3O4 quantum dots as efficient electrocatalysts to enhance the oxygen evolution electrolysis, respectively.…”

“…For example, Kuznetsov et al and Tong et al fabricated bimetallic Co-Mo alkoxide and oxygen-deficient Co3O4 quantum dots as efficient electrocatalysts to enhance the oxygen evolution electrolysis, respectively. 54,55 Cao et al reported the investigation of Cu-Ni sulfide nanowires for improving the water oxidation efficiency. 56 Chen et al fabricated Cu-Co(OH)2 nanosheets having superior electrocatalytic activity with an OER overpotantial of 300 mV at 10 mA cm -2 .…”