Boosted Oxygen Reduction Reaction Activity by Ordering Cations in the A-Site of a Perovskite Catalyst

Abstract

As concerns related to climate change continue to grow, there has been an increasing number of studies on materials that can enhance the efficiency of energy conversion/storage systems. Since the oxygen reduction reaction (ORR) is considered as a rate-determining reaction for the O 2 conversion system, it is essential to develop an efficient electrocatalyst that enables greater ORR activity. Perovskite has been explored as a promising electrocatalyst due to its excellent ORR activity at high and room temperatures. Recently, unique perovskite structures that can contain high oxygen vacancy ratios, such as brownmillerite, Ruddlesden−Popper, and layered perovskite, have been studied for exhibiting high ORR performance. However, few studies have dealt with the electrochemical properties of perovskite, which has different structures but the same cation stoichiometry, to know the exact effect of a specific structure. In this study, we synthesized two materials with different structures (cubic structure perovskite and layered structure perovskite) but with the same cation stoichiometry. The layered structure rather than the cubic structure showed cation ordering in the A-site of the perovskite structure with an enhanced oxygen vacancy ratio. As a result, the layered structure exhibits superior electrochemical performance than the cubic structure at high and room temperatures by a factor of ca. 2.7 at 500 °C in fuel cell mode, and ca. 5.5% decrease in overpotential (η) at −3 mA cm −2 for ORR catalysis. Moreover, perovskite hybridized with nitrogen doped reduced graphene oxide (N-rGO) could compensate for the intrinsic shortcoming of perovskite oxide and exert a catalytic synergy (27% decrease in η).

Comprehensive review and future perspectives: 3D printing technology for all types of solid oxide cells

“…As mentioned previously, SOCs require systems capable of sustaining high electrochemical performance during long operational durations even at low operating temperatures. Key research efforts are directed towards the formulation of electrode materials that not only have heightened redox activity [73,74] but also show the stability under the CO 2 [75], H 2 O [24], and hydrocarbon-rich environments [76]. It is equally essential to develop electrolytes materials that preserve both physicochemical stability and a high transference number across diverse conditions over long term periods [77].…”

Tailored Double Perovskite with Boosted Oxygen Reduction Kinetics and CO2 Durability for Solid Oxide Fuel Cells

“…Solid oxide fuel cell (SOFC) is widely acknowledged as a prospective energy transformation technology exhibiting the qualities of remarkable energy conversion efficiency, fuel diversity, absence of noble metal catalysis, and environmental friendliness. , SOFC offers a range of application scenarios, such as functioning as power sources for buildings and automobiles. , Moreover, SOFCs possess the capacity to function in reverse mode, allowing for the conversion of electricity back into chemical energy. , …”