Abstract
Durable, highly efficient, and economic sound electrocatalysts for CO electrooxidation (COE) are the emerging key for wide variety of energy solutions, especially fuel cells and rechargeable metal−air batteries. Herein, we report the novel system of nickel−aluminum double layered hydroxide (NiAl-LDH) nanoplates on carbon nanotubes (CNTs) network. The formulation of such complexes system was to be induced through the assistance of gold nanoparticles in order to form dual-metal active sites so as to create a extended Au/NiO two phase zone. Bis (trifluoromethylsulfonyl)imide (NTf2) anion of ionic liquid electrolyte was selected to enhance the CO/O2 adsorption and to facilitate electro-catalyzed oxidation of Ni (OH)2 to NiOOH by increasing the electrophilicity of catalytic interface. The resulting neutral catalytic system exhibited ultra-high electrocatalytic activity and stability for CO electrooxidation than commercial and other reported precious metal catalysts. The turnover frequency (TOF) of the LDH-Au/CNTs COE catalyst was much higher than the previous reported other similar electrocatalysts, even close to the activity of solid-gas chemical catalysts at high temperature. Moreover, in the long-term durability testing, the negligible variation of current density remains exsisting after 1000 electrochemistry cycles.
Highlights
Advanced electrocatalysts can power sustainable and efficient fuel cells, metal-air batteries, and electrolyzers
Since the discovery of remarkable activity in supported gold nanoparticles for CO oxidation[9], a variety of methods to prepare high activity gold catalysts have been developed, which lead to several potential applications[10]
It should be noted that only few Ni complexes have been developed for CO conversion due to the strong Ni-OH bonds, which often severely limit the activity of Ni-based catalysts in basic solution
Summary
Advanced electrocatalysts can power sustainable and efficient fuel cells, metal-air batteries, and electrolyzers. The heterogeneous catalysts with enhanced activities at high temperatures have been recently studied due to the development of multicomponent active sites, Au-metal hydroxide and oxide interfaces. In this condition, dual-metal catalytic sites with Au adjacent to oxide have shown higher catalytic activity for CO oxidation via two pathways, (1) increasing the perimeter of the boundary area for gas adsorption, and (2) forming higher activity metal complex with designed metal/ligands combination[2,3,4,5,6]. Though the Ni-based oxide/hydroxide composite catalysts have previously been made for COE7,8, this was the first time that Au assisted crystalline NiAl-LDH was synthesized electrochemically to obtain highly active electrocatalysis for COE in ionic liquid, even close to that of the most active solid/gas-phase chemical at high temperature
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