New Oxygen Regulation Strategy to Enhance the Oxygen Reduction Reaction of the Pr0.6Sr0.4Co0.2Fe0.8O3−δ Cathode through A-Site High-Entropy Engineering

Solid oxide fuel cell (SOFC) stands out as a highly promising energy conversion device, which can convert chemical energy directly into electrical energy. However, the decline in catalytic activity of the cathode becomes a major challenge for the commercialization of SOFC. Here, based on Pr0.6Sr0.4Co0.2Fe0.8O3−δ (PSCF), two novel A-site high-entropy perovskite cathodes, (Pr0.2Sr0.2La0.2Ba0.2Ca0.2)Co0.2Fe0.8O3−δ (PSLBCCF) and (Pr0.2Sr0.2La0.2Ba0.2Nd0.2)Co0.2Fe0.8O3−δ (PSLBNCF), are reported as high-catalyst-activity cathodes for SOFC. The synergistic action of high-entropy elements causes the valence state changes of the A-site Pr element and B-site Co–Fe element, which weakens the bonding energy of the metal element with O. It regulates the adsorption of surface oxygen and the dissociation of lattice oxygen, which enhances the transport of oxygen ions and greatly improves the oxygen reduction reaction and catalytic activity of the cathode. The polarization resistance (Rp) values of PSLBCCF and PSLBNCF cathodes at 750 °C are 0.083 and 0.072 Ω cm2, respectively, which are significantly lower than that of PSCF (0.122 Ω cm2). At 800 °C, the single cell supported by La0.8Sr0.2Ga0.8Mg0.2O3−δ as the electrolyte and high-entropy PSLBNCF as the cathode exhibited a power density of 561.09 mW cm–2. This study provides a new strategy for achieving excellent catalytic activity cathodes for SOFC.