No abstract

Oxygen electrocatalysts are crucial for the development of renewable and sustainable energy conversion/storage (ECS) systems, but a shortage of efficient and low-cost oxygen electrocatalysts is impeding their widespread applications. In this work, to investigate the bifunctionality of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), Ni-substituted LaMnO3 perovskite oxides (LaNi x Mn1–x O3, x = 0.1, 0.3, 0.5, 0.7, and 0.9) and pristine LaNiO3 and LaMnO3 were synthesized using a sol–gel process. After the compositional optimization and electrochemical characterizations, we identified that LaNi0.3Mn0.7O3 (SG LNM-3) within the compositions exhibited balanced intrinsic activity for bifunctional ORR and OER. To further improve the apparent activity of the optimized SG LNM-3, electrospinning was used to prepare one-dimensional nanostructured LaNi0.3Mn0.7O3 (ES LNM-3). ES LNM-3 had a higher specific surface area and continuous electron-transfer pathways, resulting in much improved bifunctional activity in comparison to SG LNM-3. In addition to the morphological effect, we ascribed the high electrochemical performance of ES LNM-3 to the high-spin Mn3+ and low-spin Ni3+ with electron configurations of t2g 3eg 1 and t2g 6eg 1 (a well-recognized design descriptor), as well as the high degree of Jahn–Teller distortion. After assembling ES LNM-3 within Zn–air batteries, promising electrochemical performances such as high power density and rate capability were obtained. Our findings will advance the development of high-performance and inexpensive oxygen electrocatalysts and associated ECS devices.

Figure 10. Electrochemical performance of PBSC and PBSC+Fe exo 3+ characterized by rechargeable Zn-air batteries. a) A schematic of a Zn-air battery, b) open-circuit-voltage profiles, c) discharge-charge polarization curves, d) discharge voltages and the power densities, e) galvanostatic discharge curves, and f) discharge-charge cycling performance.

No abstract

Active electrocatalysts are essential for the oxygen reduction reaction (ORR), which plays a crucial role in functionalizing sustainable fuel cells and Zn–air batteries (ZABs). Herein, a nominal perovskite (LaBa0.85Ca0.15Mn2O5+δ) hybrid consisting of single cubic and hexagonal perovskite structures was synthesized by electrospinning. The obtained carbon-supported one-dimensional heterostructured perovskite hybrid (1D-HPH/C) exhibits high onset and half-wave potentials of 0.879 and 0.740 V vs RHE and a high limiting current density of 6.17 mA cm–2 at 1600 rpm, which are superior to those of powder HPH/C and close to Pt/C. 1D-HPH combines the advantages of high specific surface area (14.4 m2 g–1) and optimized intrinsic activity (eg = 1), thus exhibiting outstanding electrocatalytic activity for ORR. This work demonstrates the importance of adjusting microstructure and forming a two-phase heterostructure for promoting electrocatalytic reactions of perovskite electrocatalysts.