Performance of palladium electrode for electrochemical hydrogen pump using strontium-zirconate-based proton conductors

Abstract

An electrode design with no use of three-phase boundary was investigated using palladium electrode. The hydrogen evolution rate of the palladium electrode cell using SrZr 0.9 Y 0.1 O 3−α electrolyte followed Faraday's law up to 180 mA cm −2 , and the anode and cathode overpotentials were significantly lower than those of a platinum electrode cell, suggesting that the palladium electrode is effective to improve the performance of the hydrogenpumping cell using SrZrO 3 -based electrolyte. The ratedetermining step (RDS) for electrode reaction was also investigated by changing the electrode morphology and hydrogen partial pressure, and it was suggested that the RDS of the anode is a reaction at electrode/electrolyte interface.

A Review of Applications, Prospects, and Challenges of Proton-Conducting Zirconates in Electrochemical Hydrogen Devices

“…Proton-conducting perovskite oxides such as barium zirconate (BaZr 0 .1 Ce 0 .7 Y 0 .2 O 3−δ ), calcium zirconate (CaZr 0.96 In 0.04 O 3 ), and strontium zirconate (SrZr 0.9 Y 0.1 O 3−α ) are used as an electrolyte layer, and hydrogen is produced in the cathode [ 90 , 91 , 92 ]. Even though cerate-based perovskites can also be used as an electrolyte, cerate easily reacts with H 2 O and CO 2 (usually present in the by-product gases) [ 92 ].…”

“…Proton-conducting perovskite oxides such as barium zirconate (BaZr 0 .1 Ce 0 .7 Y 0 .2 O 3−δ ), calcium zirconate (CaZr 0.96 In 0.04 O 3 ), and strontium zirconate (SrZr 0.9 Y 0.1 O 3−α ) are used as an electrolyte layer, and hydrogen is produced in the cathode [ 90 , 91 , 92 ]. Even though cerate-based perovskites can also be used as an electrolyte, cerate easily reacts with H 2 O and CO 2 (usually present in the by-product gases) [ 92 ]. Because of the chemical stability and relative reactivity against carbon dioxide, zirconate-based perovskites like doped strontium zirconate with yttrium have been usedan electrolyte with palladium electrodes and utilized as a hydrogen pump [ 92 ].…”

“…Even though cerate-based perovskites can also be used as an electrolyte, cerate easily reacts with H 2 O and CO 2 (usually present in the by-product gases) [ 92 ]. Because of the chemical stability and relative reactivity against carbon dioxide, zirconate-based perovskites like doped strontium zirconate with yttrium have been usedan electrolyte with palladium electrodes and utilized as a hydrogen pump [ 92 ]. To a similar end, scientists have used ytterbium doping for a similar hydrogen pump mechanism with Ni/SiO 2 porous electrodes [ 79 ].…”

“…Sakai et al (2009) [ 92 ] used palladium as an electrode to enhance the performance of the hydrogen pump. Since proton-conducting electrolyte SZY-91 was used, hydrogen was directly produced in the cathode without any separation process.…”

“…Hydrogen pumping technologies are essential in a nuclear fusion plant. These hydrogen pumps utilize the methods of electrochemical cell technologies where some researchers used zirconate ceramic materials as electrolytes [ 97 ] and platinum/palladium/nickel materials as electrodes [ 79 , 92 , 112 ]. The main drawback of these methods still lies with material selection.…”