Electronic structure modulation of unusual phase of metal nanomaterials for catalysis

Abstract

A heterostructured electrocatalyst for carbon dioxide reduction reaction includes a lanthanide oxide nanomaterial deposited on a gold-containing nanosupport. A method of preparing the heterostructured electrocatalyst and use of the heterostructured electrocatalyst in an electrode are also addressed.

1 . A heterostructured electrocatalyst for carbon dioxide reduction reaction comprising a lanthanide oxide nanomaterial deposited on a gold-containing nanosupport. 
     
     
         2 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein the gold-containing nanosupport is physically distinguishable from the lanthanide oxide nanomaterial. 
     
     
         3 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein structure of the lanthanide oxide nanomaterial is different from that of the gold-containing nanosupport. 
     
     
         4 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein the lanthanide oxide nanomaterial comprises a nanoparticle of cerium oxide. 
     
     
         5 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein oxidation state of the gold in the gold-containing nanosupport is different from that of the lanthanide in the lanthanide oxide nanomaterial. 
     
     
         6 . The heterostructured electrocatalyst as claimed in  claim 5 , wherein the oxidation state of the gold is 0 and the oxidation state of the lanthanide is +3 or +4. 
     
     
         7 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein the gold-containing nanosupport has a hetero-crystal phase of 4H/fcc. 
     
     
         8 . The heterostructured electrocatalyst as claimed in  claim 1 , wherein the lanthanide oxide nanomaterial has a homo-crystal phase of fcc. 
     
     
         9 . The heterostructured electrocatalyst as claimed in  claim 7 , wherein the gold-containing nanosupport is a 4H/fcc gold nanorod. 
     
     
         10 . The heterostructured electrocatalyst as claimed in  claim 8 , wherein the lanthanide oxide nanomaterial is a fcc cerium oxide nanoparticle. 
     
     
         11 . The heterostructured electrocatalyst as claimed in  claim 9 , wherein the 4H/fcc gold nanorod is partially covered by the fcc cerium oxide nanoparticles to provide a metal-oxide interface as reactive sites for electrocatalytic carbon dioxide reduction reaction. 
     
     
         12 . The heterostructured electrocatalyst as claimed in  claim 10 , wherein the gold-containing nanosupport has a deposit of about 3 nm to about 10 nm of fcc cerium oxide nanoparticles. 
     
     
         13 . The heterostructured electrocatalyst as claimed in  claim 10 , wherein the lanthanide oxide nanomaterial include cerium (IV) oxide nanoparticles and cerium (III) oxide nanoparticles at a ratio of about 2:1. 
     
     
         14 . The heterostructured electrocatalyst as claimed in  claim 11 , wherein atomic ratio of gold:cerium is about 3:1 to about 5:1. 
     
     
         15 . The heterostructured electrocatalyst as claimed in  claim 11 , wherein the 4H/fcc gold nanorod has a diameter of about 12 nm to about 25 nm and a length of about 400 nm to about 900 nm. 
     
     
         16 . A method of preparing the heterostructured electrocatalyst as claimed in  claim 1 , comprising the steps of:
 a) providing a reaction mixture including a hetero-crystal phase gold-containing nanosupport, a lanthanide precursor and a first reducing agent;   b) heating the reaction mixture at a temperature of about 100° C. for about 5 mins; and   c) isolating the electrocatalyst from the reaction mixture.   
     
     
         17 . The method as claimed in  claim 16 , wherein the gold-containing nanosupport is suspended in ethanol. 
     
     
         18 . The method as claimed in  claim 17 , wherein the gold-containing nanosupport comprises a 4H/fcc gold nanorod formed from the steps of:
 providing a closed reaction mixture including gold (III) chloride hydrate, n-heptane, a surfactant including oleylamine, and a second reducing agent including N-ethylcyclohexylamine;   heating the closed reaction mixture at about 68° C. for about 48 h to form crude 4H/fcc gold nanorod;   isolating the crude 4H/fcc gold nanorod from the closed reaction mixture;   
       purifying the isolated 4H/fcc gold nanorod by successively washing the isolated 4H/fcc gold nanorod with cyclohexane, a cyclohexane/ethanol mixture (1:1, v/v), and ethanol; and
 resuspending the washed 4H/fcc gold nanorod in ethanol to obtain an ethanol suspension of the 4H/fcc gold nanorod. 
 
     
     
         19 . The method as claimed in  claim 16 , wherein the lanthanide precursor comprises cerium nitrate hexahydrate, and the first reducing agent comprises hexamethylenetetramine. 
     
     
         20 . The method as claimed in  claim 19 , wherein the lanthanide precursor and the first reducing agent have a concentration ratio of 1:1. 
     
     
         21 . The method as claimed in  claim 20 , wherein the lanthanide precursor includes a concentration of 1 mg/mL to 3 mg/mL. 
     
     
         22 . The method as claimed in  claim 20 , wherein the first reducing agent includes a concentration of 1 mg/mL to 3 mg/mL. 
     
     
         23 . An electrode for carbon dioxide reduction reaction comprising an electrocatalytically active mixture including the heterostructured electrocatalyst as claimed in  claim 1  provided on a conductive substrate. 
     
     
         24 . The electrode as claimed in  claim 23 , wherein the conductive substrate comprises glassy carbon. 
     
     
         25 . The electrode as claimed in claimed in  claim 23 , wherein the electrocatalytically active mixture further includes carbon black and tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer. 
     
     
         26 . The electrode as claimed in  claim 23  having a working area of about 0.5 cm 2 . 
     
     
         27 . The electrode as claimed in  claim 23  having a catalyst loading of about 400 μg cm −2 .