Abstract
Efficient oxygen evolution reaction (OER) electrocatalysts are highly desired in the field of water electrolysis and rechargeable metal-air batteries. In this study, a chelate polymer, composed of copper (II) and dithiooxamide, was used to derive an efficient catalytic system for OER. Upon potential sweep in 1 M KOH, copper (II) centers of the chelate polymer were transformed to CuO and Cu(OH)2. The carbon-dispersed CuO nanostructures formed a nanocomposite which exhibits an enhanced catalytic activity for OER in alkaline media. The nanocomposite catalyst has an overpotential of 280 mV (at 1 mA/cm2) and a Tafel slope of 81 mV/dec in 1M KOH solution. It has a seven-fold higher current than an IrO2/C electrode, per metal loading. A catalytic cycle is proposed, in which CuO undergoes electrooxidation to Cu2O3 that further decomposes to CuO with the release of oxygen. This work reveals a new method to produce an active nanocomposite catalyst for OER in alkaline media using a non-noble metal chelate polymer and a porous carbon. This method can be applied to the synthesis of transition metal oxide nanoparticles used in the preparation of composite electrodes for water electrolyzers and can be used to derive cathode materials for aqueous-type metal-air batteries.
Highlights
The oxygen evolution reaction (OER) is an important half-reaction in the field of electrochemical energy storage and conversion [1,2,3]
The OER requires a thermodynamic potential of 1.23 V vs. the reversible hydrogen electrode (RHE) and follows different chemical routes depending on pH
An efficient electrocatalytic system for the OER in alkaline solutions has been developed by the in situ electrochemical oxidation of Cu(dto) chelate polymer in a carbon matrix
Summary
The oxygen evolution reaction (OER) is an important half-reaction in the field of electrochemical energy storage and conversion [1,2,3]. The development of an efficient, durable and cost-effective electrocatalyst for the OER is required for the advancement of a number of sustainable energy technologies involving water electrolyzers and metal–air batteries. IrO2 and RuO2 are used as catalysts for the OER due to their low overpotential [6]. The high price of Ir and Ru metals, as well as the instability of RuO2 and IrO2 at high anodic potentials are major drawbacks that are driving the development of new OER catalysts. Various metal and metal oxide nanoparticles have been tested as OER catalysts in alkaline solutions [3,7,8]. Co, Fe, Mn, Ni and Cu were frequently investigated The performance of these catalysts in the OER are frequently summarized in terms of the Catalysts 2020, 10, 233; doi:10.3390/catal10020233 www.mdpi.com/journal/catalysts
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