FeNi decorated nitrogen-doped hollow carbon spheres as ultra-stable bifunctional oxygen electrocatalyst for rechargeable zinc-air battery with 2.7% decay after 300 hours cycling.

Research on non-noble metal bifunctional electrocatalysts with high efficiency and long-lasting stability is crucial for many energy storage devices such as zinc-air batteries. In this report, nitrogen-doped porous hollow carbon spheres with a size of about 300 nm were fabricated using a modified Stöber method and decorated with an FeNi alloy through a pyrolytic reduction process, resulting in a promising bifunctional electrocatalyst for both the oxygen evolution reaction and oxygen reduction reaction. The as-prepared FeNi@NHCS electrocatalyst exhibits excellent bifunctional activity in KOH electrolyte, attributed to its mesoporous structure, large specific surface area, and the strong coupling between the FeNi nanoalloy and nitrogen-doped carbon carriers. The electrocatalyst demonstrates excellent ORR performance with E1/2 = 0.828 V and OER activity with Ej=10 mA = 1.51 V. A zinc-air battery using FeNi@NHCS as the air electrode achieves an open-circuit voltage of 1.432 V and a maximum power density of 181.8 mW cm-2. After 300 h of galvanostatic charge-discharge cycles, the charge-discharge voltage gap (ΔU) of the battery had only decayed by 2.7%, demonstrating superior cycling stability.

Highly oriented platinum/iridium thin films for high-temperature thermocouples with superior precision.

The long-term precise high-temperature measurement of thin-film thermocouples (TFTCs) has attracted attention due to the capability of instantaneous temperature detection. However, related technologies have seen slow development, and there is no one standard TFTC yet. Here, we focus on a new strategy of reducing alloys for the easy preparation and performance enhancement of TFTCs via nanostructure and interface design. To this end, we fabricated a platinum/iridium (Pt/Ir) pure-element TFTC with a well matched interface and few defects, which demonstrated excellent long-term service stability over a high-temperature range. The corresponding polynomial fitting coefficients were ≥0.99999, indicating the accurate acquisition of temperature data. A reduced deviation (<0.21%) between three calibration cycles was obtained over a wide temperature range of 300 °C to 1000 °C, which is better than the maximum precision of a standard wire thermocouple. Superior properties are achieved because of the resulting fewer defects in the Pt and Ir thin films with highly preferential orientation along the (111) plane. The results indicate that our Pt/Ir TFTCs have significant potential for application in many domains such as thermal detection, microelectronics and aero-engines.