Dopant-Free Conductive SnO2/CNT Support for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis

Abstract

Polymer electrolyte membrane water electrolysis (PEMWE) is an energy conversion device for producing green hydrogen, which is one of the key elements for moving toward a hydrogen society. However, there are two obstacles to the commercialization of PEMWE, which are cost and durability. In particular, a large amount of a noble metal catalyst such as ruthenium (Ru) or iridium (Ir) is required for the oxygen evolution reaction (OER) occurring at the anode electrode. To reduce the usage of noble metal catalysts, carbon supports could be introduced. However, due to the harsh conditions resulting from the high voltage and acidic environment in the anode, the carbon easily corrodes and decomposes into carbon dioxide. To prevent corrosion of support materials, metal oxide support can be used. Tin oxide (SnO2) is one of good candidate support because it is stable under acidic and high potential conditions. However, the electrical conductivity of SnO2 needs to be increased to be used as an anode support material for PEMWE. In previous studies, the electrical conductivity of SnO2 was increased by the introduction of dopants such as antimony (Sb), indium (In), fluorine (F) and so on. However, recently, it was reported that these dopants can be dissolved under the OER conditions. Thus, a new approach for synthesizing dopant-free and stable metal oxide supports is required.Herein, we report tin oxide-carbon nanotube composite (SnO2-CNT) support for the anode in PEMWE. The SnO2 nanoparticles were coated on CNT for high conductivity and stability. For evaluating the electrochemical performance, Ir nanoparticles were supported on SnO2-CNT. Ir/SnO2-CNT showed high OER activity and stability under acidic conditions. These results demonstrated that SnO2-CNT support can be utilized for reducing the amount of precious metal catalysts and increasing the stability of OER supported catalyst in PEMWE.