Abstract:Oxygen reduction reaction, which proceeds at the cathode of a fuel cell, is primarily important as its rate determines the overall performance of the device. However, designing a single-phase material...
“…8 – 11 ). The in situ formed Nb-deficient BCFN NPs on BCFN electrodes are expected to exhibit better structural stability since the risk of agglomeration is greatly reduced, thus enhancing the durability and thermal stability of the electrode 57 – 60 . Fig.…”
Reversible protonic ceramic electrochemical cells (R-PCECs) are ideally suited for efficient energy storage and conversion; however, one of the limiting factors to high performance is the poor stability and insufficient electrocatalytic activity for oxygen reduction and evolution of the air electrode exposed to the high concentration of steam. Here we report our findings in enhancing the electrochemical activity and durability of a perovskite-type air electrode, Ba0.9Co0.7Fe0.2Nb0.1O3-δ (BCFN), via a water-promoted surface restructuring process. Under properly-controlled operating conditions, the BCFN electrode is naturally restructured to an Nb-rich BCFN electrode covered with Nb-deficient BCFN nanoparticles. When used as the air electrode for a fuel-electrode-supported R-PCEC, good performances are demonstrated at 650 °C, achieving a peak power density of 1.70 W cm−2 in the fuel cell mode and a current density of 2.8 A cm−2 at 1.3 V in the electrolysis mode while maintaining reasonable Faradaic efficiencies and promising durability.
“…8 – 11 ). The in situ formed Nb-deficient BCFN NPs on BCFN electrodes are expected to exhibit better structural stability since the risk of agglomeration is greatly reduced, thus enhancing the durability and thermal stability of the electrode 57 – 60 . Fig.…”
Reversible protonic ceramic electrochemical cells (R-PCECs) are ideally suited for efficient energy storage and conversion; however, one of the limiting factors to high performance is the poor stability and insufficient electrocatalytic activity for oxygen reduction and evolution of the air electrode exposed to the high concentration of steam. Here we report our findings in enhancing the electrochemical activity and durability of a perovskite-type air electrode, Ba0.9Co0.7Fe0.2Nb0.1O3-δ (BCFN), via a water-promoted surface restructuring process. Under properly-controlled operating conditions, the BCFN electrode is naturally restructured to an Nb-rich BCFN electrode covered with Nb-deficient BCFN nanoparticles. When used as the air electrode for a fuel-electrode-supported R-PCEC, good performances are demonstrated at 650 °C, achieving a peak power density of 1.70 W cm−2 in the fuel cell mode and a current density of 2.8 A cm−2 at 1.3 V in the electrolysis mode while maintaining reasonable Faradaic efficiencies and promising durability.
“…In humid and oxidizing atmospheres, protons can be introduced into the oxides by the hydrogenation reaction, as shown in eqn (6). As a result, two hydroxide defects are generated with an emission of half O 2 :…”
Section: Defect Generation In Proton-conducting Materialsmentioning
confidence: 99%
“…55 It can be seen that both proton and oxygen ion conduction are highly dependent on oxygen vacancies, especially for the oxides in a humid atmosphere, where the hydration reaction (eqn (4)) occurs. Moreover, two lattice oxygen ions can capture one adsorbed H 2 O and generate two hydroxide defects in the humid air simultaneously, and such a reaction is known as the hydrogenation reaction (eqn (6)). The proton then diffuses according to the Grotthuss mechanism in the perovskite lattice.…”
Section: More Than Proton:oxygen Ion Transport and Electronic Conduct...mentioning
confidence: 99%
“…There are mainly two types of SOFCs, i.e. , traditional oxide ion-conducting fuel cells (O-SOFCs), which use oxygen ion conductors, such as yttria stabilized zirconia (YSZ) and doped ceria, as electrolytes, 5,6 and protonic ceramic fuel cells (PCFCs), 7 which use proton-conducting oxides as electrolytes. Currently, there is substantially increased interest in PCFCs for power generation because they have great potential for operation at reduced temperature, considering the high mobility of protons and the higher energy efficiency by avoiding the dilution effect of water on fuel gas.…”
Section: Introductionmentioning
confidence: 99%
“…Among various types of fuel cells, solid oxide fuel cells (SOFCs), composed of ceramic oxides, are particularly interesting because of their low material cost with non-noble metal catalysts, high stability due to their all-solid cell configuration, high electrode reaction kinetics due to elevated operating temperature, and superior values of exhaust heat, which are highly promising for stationary power generation. 4 There are mainly two types of SOFCs, i.e., traditional oxide ion-conducting fuel cells (O-SOFCs), which use oxygen ion conductors, such as yttria stabilized zirconia (YSZ) and doped ceria, as electrolytes, 5,6 and protonic ceramic fuel cells (PCFCs), 7 which use proton-conducting oxides as electrolytes. Currently, there is substantially increased interest in PCFCs for power generation because they have great potential for operation at reduced temperature, considering the high mobility of protons and the higher energy efficiency by avoiding the dilution effect of water on fuel gas.…”
Protonic ceramic fuel cells (PCFCs), capable of harmonious and efficient conversion of chemical energy into electric power at reduced temperature enabled by fast proton conduction, are promising energy technology, which...
The sluggish kinetics of oxygen reduction reaction (ORR) at low temperatures and the fast degradation of the cathode are the main obstacles to the commercialization of solid oxide fuel cells (SOFCs). However, it is still very challenging to achieve both high catalytic activity and favorable stability for single‐phase materials. Herein, a highly active and durable nanocomposite cathode (Ba0.5Sr0.5)0.75Pr0.25Co0.575Fe0.3W0.125O3‐δ (BSPCFW) for low‐temperature SOFC (≤650 °C) is presented, which self‐assembles into two cubic perovskites: the simple perovskite Pr0.38Ba0.25Sr0.37Co0.62Fe0.38O3‐δ (PBSCF‐c) and the B‐site cations ordered double perovskite Ba1.30Sr0.70Co1.0Fe0.25W0.75O6‐δ (BSCFW‐c). The former PBSCF‐c serves as the highly conductive and active catalyst for ORR, while the latter BSCFW‐c with a large lattice parameter introduces a key beneficial lattice tensile strain into the PBSCF‐c phase through a coherent interface, which significantly promotes the ORR activity at low temperatures with the area specific resistance of 0.034 Ω cm2 at 650 °C, and the long‐term stability of 2 years storage and 1280 h operation in symmetrical cell. The introduction of the beneficial lattice tensile strain in self‐assembled composite catalysts is an effective way to synergistically enhance the electrochemical activity and durability of the electrode materials for electrochemical devices.
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