Lead electrode for electrochemical reduction of carbon dioxide and method of preparing thereof

Abstract

An electrode includes a transparent substrate, a lead (Pb) layer at least partially covering a surface of the transparent substrate. The Pb layer includes irregular octahedral-shaped Pb particles having an average particle size of from 0.5 to 3 micrometers (μm). The irregular octahedral-shaped Pb particles are uniformly distributed on a surface of the Pb layer. A method of making the electrode is also provided. A method for electrochemical carbon dioxide (CO2) reduction (CO2RR).

1 . An electrode, comprising:
 a transparent substrate;   a lead (Pb) layer at least partially covering a surface of the transparent substrate;   wherein the Pb layer comprises irregular octahedral-shaped Pb particles having an average particle size of from 0.5 to 3 micrometers (μm);   wherein the irregular octahedral-shaped Pb particles are uniformly distributed on a surface of the Pb layer.   
     
     
         2 . The electrode of  claim 1 , wherein the transparent substrate is a glass substrate selected from the group consisting of a fluorine doped tin oxide (FTO) glass substrate, a tin doped indium oxide (ITO) glass substrate, an aluminum doped zinc oxide (AZO) glass substrate, a niobium doped titanium dioxide (NTO) glass substrate, an indium doped cadmium oxide (ICO) glass substrate, an indium doped zinc oxide (IZO) glass substrate, a fluorine doped zinc oxide (FZO) glass substrate, a gallium doped zinc oxide (GZO) glass substrate, an antimony doped tin oxide (ATO) glass substrate, a phosphorus doped tin oxide (PTO) glass substrate, a zinc antimonate glass substrate, a zinc oxide glass substrate, a ruthenium oxide glass substrate, a rhenium oxide glass substrate, a silver oxide glass substrate, and a nickel oxide glass substrate. 
     
     
         3 . The electrode of  claim 1 , wherein the transparent substrate is a glassy carbon substrate. 
     
     
         4 . The electrode of  claim 1 , wherein the Pb layer has an arithmetic average roughness (Sa) in a range of 2.5 to 3.8 μm. 
     
     
         5 . The electrode of  claim 1 , wherein the Pb layer has a root mean square roughness (Sq) in a range of 3.0 to 5.7 μm. 
     
     
         6 . The electrode of  claim 1 , having a current density of 40 to 100 milliamperes per square centimeter (mA/cm 2 ) at a potential of −0.5 to −0.7 Volt (V Ag/AgCl ). 
     
     
         7 . The electrode of  claim 1 , having a Tafel slope of 200 to 360 millivolts per decade (mV/decade) for CO production in a salt solution at a scan rate of 5 to 50 millivolts per second (mV/s). 
     
     
         8 . A method of making the electrode of  claim 1 , comprising:
 disposing a lead sheet on a surface of the transparent substrate to form a Pb-coated substrate having the Pb layer;   immersing the Pb-coated substrate into a solution comprising a potassium salt and applying a cyclic voltammetry (CV) potential to the Pb-coated substrate to form substantially irregular octahedral-shaped Pb particles on the surface of the Pb layer; and   removing the Pb-coated substrate from the electrolyte solution, washing and drying to form the electrode;   wherein the irregular octahedral-shaped Pb particles has an average particle size of about 1 μm and are uniformly distributed on the surface of the Pb layer.   
     
     
         9 . The method of  claim 8 , wherein the potassium salt comprises potassium chloride (KCl), and wherein the KCl is present in the solution at a concentration of 0.001 to 1 molar (M). 
     
     
         10 . The method of  claim 8 , wherein the CV potential is in a range of from −0.5 to −0.7 V Ag/AgCl at a scan rate of 10 to 30 mV/s. 
     
     
         11 . The method of  claim 8 , wherein the applying of the cyclic voltammetry is performed for 1 to 100 cycles. 
     
     
         12 . A method of electrochemical carbon dioxide (CO 2 ) reduction (CO 2 RR), comprising;
 charging an electrolyte to an electrochemical cell comprising a working electrode, a counter electrode, and a reference electrode;   introducing a CO 2 —containing gas composition into the electrochemical cell containing the electrolyte and passing the CO 2 —containing gas composition through the CO 2 —containing gas composition; and   during the passing, simultaneously applying a potential between the working electrode and the counter electrode in the electrochemical cell via the electrolyte to form a product comprising carbon monoxide (CO) and a formate species;   wherein the working electrode comprises the electrode of  claim 1 ; and   wherein the formate species is bonded to the surface of the electrode;   
     
     
         13 . The method of  claim 12 , wherein the electrochemical cell is a H-type sealed two-compartment electrolytic cell separated by a proton exchange membrane. 
     
     
         14 . The method of  claim 12 , wherein the electrolyte comprising an aqueous solution of a salt having a concentration of 0.05 to 2 M. 
     
     
         15 . The method of  claim 14 , wherein the salt comprises potassium bicarbonate (KHCO 3 ), and sodium bicarbonate (NaHCO 3 ). 
     
     
         16 . The method of  claim 12 , wherein CO 2  is present in the CO 2 —containing gas composition at a concentration of at least 90 wt. % based on a total weight of the CO 2 —containing gas composition. 
     
     
         17 . The method of  claim 12 , wherein the CO 2 —containing gas composition is introduced into the electrochemical cell at a rate of 1 to 50 standard cubic centimeters per minute (sccm). 
     
     
         18 . The method of  claim 12 , wherein the formate species comprises at least one of sodium formate, potassium formate, and formic acid, and wherein the product further comprises hydrogen, ethanol, and methanol. 
     
     
         19 . The method of  claim 12 , having a CO faradaic efficiency (FE) of about 89% based on the total charge passed during the applying the potential; and 
     
     
         20 . The method of  claim 12 , having a CO production rate of from 25 to 35 micromoles per hour per square centimeter (μmol hr −1  cm −2 ) at an overpotential of −0.8 to −0.6 V RHE .