Catalytic compositions and methods for ethanol oxidation

Abstract

In one aspect, nanoparticles for ethanol oxidation are described herein, which comprise a core including at least one Group IB metal and a shell disposed over the core, wherein the shell comprises islands of alloyed platinum group metals. In another aspect, an electrode is described herein, which in some embodiments, comprises a substrate and electrocatalytic nanoparticles deposited over the substrate. In some embodiments, the electrode described herein further comprises a layer of carbon nanoparticles positioned between the substrate and the electrocatalytic nanoparticles. In yet another aspect, a method of ethanol oxidation is described herein. In some embodiments, such a method comprises (i) providing an electrode comprising a substrate and electrocatalytic nanoparticles deposited over the substrate, (ii) disposing the electrode in an alkaline medium comprising ethanol; and (iii) oxidizing the ethanol with the electrode.

1 . A nanoparticle comprising:
 a core including at least one Group IB metal; and   a shell disposed over the core, the shell comprising islands of alloyed platinum group metals.   
     
     
         2 . The nanoparticle composition of  claim 1 , wherein the islands of alloyed platinum group metals exhibit monolayer thickness. 
     
     
         3 . The nanoparticle composition of  claim 1 , wherein the islands comprising platinum-iridium alloy. 
     
     
         4 . The nanoparticle composition of  claim 3 , wherein a ratio of platinum to iridium in the alloy is greater than 1. 
     
     
         5 . The nanoparticle composition of  claim 3 , wherein the platinum-iridium alloy is of the formula PtIt x  with x being 0.6-0.7. 
     
     
         6 . The nanoparticle composition of  claim 1 , wherein the core comprises gold, silver or an alloy of gold and silver. 
     
     
         7 . The nanoparticle composition of  claim 1 , having a diameter of 3-8 nm. 
     
     
         8 . The nanoparticle of  claim 1 , wherein the Group IB metal of the core induces lattice expansion in the islands of alloyed platinum group metals. 
     
     
         9 . The nanoparticle composition of  claim 8 , wherein the islands of alloyed platinum group metals exhibit tensile stress. 
     
     
         10 . The nanoparticle composition of  claim 1 , wherein the islands of alloyed platinum group metals form an interface with the core. 
     
     
         11 . The nanoparticle of  claim 1 , wherein at least one Group IB metal of the core has a single crystal structure. 
     
     
         12 . The nanoparticle of  claim 1 , wherein a molar ratio of the alloyed platinum group metals in the shell to the Group IB metal of the core ranges from 0.1 to 0.2. 
     
     
         13 . The nanoparticle of  claim 1 , wherein the core is spherical or elliptical. 
     
     
         14 . The nanoparticle of  claim 1 , wherein the core is polygonal. 
     
     
         15 . An electrode comprising:
 a substrate; and   electrocatalytic nanoparticles deposited over the substrate, the electrocatalytic nanoparticles comprising a core-shell architecture, wherein the core comprises at least one Group IB metal, and the shell comprises islands of alloyed platinum group metals.   
     
     
         16 . The electrode of  claim 15  further comprising a layer of carbon nanoparticles positioned between the substrate and the electrocatalytic nanoparticles. 
     
     
         17 . The electrode of  claim 15 , wherein the electrocatalytic nanoparticles have an average size of 3-8 nm. 
     
     
         18 . The electrode of  claim 15 , wherein the electrocatalytic nanoparticles provide a peak current of at least 50 A/mg of platinum group metal during ethanol oxidation in alkaline media. 
     
     
         19 . The electrode of  claim 18 , wherein the electrocatalytic nanoparticles provide a peak current of at least 50-60 A/mg of platinum group metal during the ethanol oxidation. 
     
     
         20 . The electrode of  claim 15 , wherein the electrocatalytic nanoparticles are selective to a C1-12 electron pathway for ethanol oxidation. 
     
     
         21 . The electrode of  claim 15 , wherein the electrocatalytic nanoparticles provide an onset potential of 0.4 V to 0.5 V for ethanol oxidation. 
     
     
         22 . The electrode of  claim 20 , wherein the C1-12 electron pathway accounts for greater than 50 percent of current generated during ethanol oxidation. 
     
     
         23 . The electrode of  claim 15 , wherein the islands of alloyed platinum group metals exhibit monolayer thickness. 
     
     
         24 . The electrode of  claim 15 , wherein the islands comprise platinum-iridium alloy. 
     
     
         25 . The electrode of  claim 15 , wherein the Group IB metal of the core induces lattice expansion in the islands of alloyed platinum group metals. 
     
     
         26 . A method of ethanol oxidation comprising:
 providing an electrode comprising a substrate and electrocatalytic nanoparticles deposited over the substrate, the electrocatalytic nanoparticles comprising a core-shell architecture, wherein the core comprises at least one Group IB metal, and the shell comprises islands of alloyed platinum group metals;   disposing the electrode in an alkaline medium comprising ethanol; and   oxidizing the ethanol with the electrode.