Preparation Of3D-Cu Electrode And3D-Pb Electrode And Their Application To Electroreduction Of CO₂to HCOOH

As an electrode material, copper has been widely used; and for lead,which has a highoverpotential for hydrogen evolution, is an ideal catalyst for the electroreduction of CO2toformate. In this paper, this two kinds of materials were used in the study of electroreductionof CO2to formate.3D-copper electrode was prepared by electrodepositing a porous copperfilm onto the copper stick by applying a constant potential, hydrogen bubbles being usedas dynamic template. Then, this copper film was used as a hard template to prepare a3D-lead electrode by electrodepositing a porous lead film onto it.3D-lead electrode hada three-dimensional porous morphology, and the lead was cuboid, cubic crystal structure.The coarse porous copper film between the copper substrate layer and the porous lead layercould strength the binding between them.These three kinds of electrodes, copper electrode3D-copper electrode and3D-leadelectrode, were used in the electroreduction of CO2to formate, and it was found that cop-per electrode had a better catalytic activity to the formation of formate than3D-copper elec-trode, the best current efciency was more than40%. Increasing of active area and changingof current density may lead to the formation of more hydrocarbons for the3D-copper elec-trode, which may be the reason for its decreasing of current efciency to formate. Amongthe potentials and electrolyte concentrations studied,3D-lead electrode had the best cat-alytic activity. When the potential was-1.7V vs. SCE and the electrolyte concentrationwas0.3M, the current efciency to formate was92%. There was some relationship be-tween current density and current efciency, to copper electrode and3D-copper electrode,current efciency for formate decreased with increasing of current density. And to3D-leadelectrode, in smaller current density regions, current efciency increased with increasingof current density; in larger current density, current efciency decreased with increasing ofcurrent density.In the long time electroreduction of CO2, current efciency to formate decreased withtime extending when3D-lead electrode was used. SEM showed the slice on the surfaceof the electrode decreased with time going on. XRD showed that the difraction peak oflead was not the strongest when formate current efciency was the highest. And CV testsshowed the current density was getting lower. These proved that the decreasing of activearea of electrode caused by morphology changing led to the decreasing of current efciency.