Development of Electrode-Supported Proton Conducting Solid Oxide Cells and their Evaluation as Electrochemical Hydrogen Pumps

Abstract

Protonic ceramic solid oxide cells (P-SOCs) have gained widespread attention due to their potential for operation in the temperature range of 300–500 °C, which is not only beneficial in terms of material stability but also offers unique possibilities from a thermodynamic point of view to realize a series of reactions. For instance, they are ideal for the production of synthetic fuels by hydrogenation of carbon dioxide and nitrogen, upgradation of hydrocarbons, or dehydrogenation reactions. However, the development of P-SOC is quite challenging because it requires a multifront optimization in terms of material synthesis and fabrication procedures. Herein, we report in detail a method to overcome various fabrication challenges for the development of efficient and robust electrode-supported P-SOCs (Ni-BCZY/BCZY/Ni-BCZY) based on a BaCe 0.2 Zr 0.7 Y 0.1 O 3−δ (BCZY271) electrolyte. We examined the effect of pore formers on the porosity of the Ni-BCZY support electrode, various electrolyte deposition techniques (spray, spin, and vacuum-assisted), and thermal treatments for developing robust and flat half-cells. Half-cells containing a thin (10–12 μm) pinhole-free electrolyte layer were completed by a screen-printed Ni-BCZY electrode and evaluated as an electrochemical hydrogen pump to access the functionality. The P-SOCs are found to show a current density ranging from 150 to 525 mA cm –2 at 1 V over an operating temperature range of 350–450 °C. The faradaic efficiency of the P-SOCs as well as their stability were also evaluated.

A review of progress in proton ceramic electrochemical cells: material and structural design, coupled with value-added chemical production

“…Since the early 1980s, proton-conducting oxides have been employed as hydrogen pumps for the purpose of H 2 separation or extraction. [375][376][377] In general, hydrogen pumping is a distinct operational approach within the fuel cell mode. The difference with a fuel cell is the presence of an externally applied voltage and the occurrence of a reaction at the air electrode.…”

Fundamental Understanding and Applications of Protonic Y‐ and Yb‐Coped Ba(Ce,Zr)O3 Perovskites: State‐of‐the‐Art and Perspectives

“…[15][16][17] Generally, protons in oxides can co-exist with other charge carriers (oxygen-ions/oxygen vacancies, electrons, holes), showing either predominantly protonic or co-ionic, as well as mixed ionicelectronic and triple-conducting behaviors. In the light of these transport variations, PCOMs can be used as electrolytes for various electrochemical devices (including solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs), electrochemical converters, pumps, and sensors), [18][19][20][21][22][23] as electrode materials for the same devices, [24][25][26] or as hydrogen-or steam permeable membranes. [27,28] The use of PCOMs is associated with many advantages, [29][30][31][32] including a significant reduction of SOFC and SOEC operation temperatures (down to 400-600 °C) as compared with classical devices based on oxygen-conducting electrolytes (which typically operate at temperatures above 700 °C), as well as the realization of unique H-participating conversion processes, such as non-oxidative alkane dehydration and non-catalytic alcohol or ammonia synthesis.…”