Tunning the single-phase triggered 3D mesostructured nitride with engineering the thermal nitridation effect for zinc-air batteries

Abstract

Metallic surface constituents and partial oxidation are two factors that significantly influence not only the structure and morphology but also the performance and durability of an electrocatalyst. Herein, we report a structural design and optimization of a three-dimensional mesoporous electrocatalyst Ni3FeN through nanocasting followed by a thermal-nitridation process. Using annealing in NH3 ambiance at various controlled temperatures, different samples are synthesized. The sample Ni3FeN-420 (along with a secondary phase - metallic alloy Ni3Fe) annealed at 420 °C shows good catalytic activity reflected in very low overpotential (249 mV) towards oxygen evolution reaction (OER). The reached overpotential (η10) is lower than that observed in other ammoniated ternary nitrides (prepared using 370, 400, and 450 °C annealing temperatures), and metallic alloy Ni3Fe electrocatalysts. Also with due benchmarking, the superiority of Ni3FeN-420 is demonstrated. The material also has excellent durability showing no significant activity loss after 2000 cycles along with long-term stability with an irrelevant drop of activity noted after 10 h toward OER in an alkaline electrolyte. Furthermore, the mixture of Ni3FeN-420 with Pt/C loaded on the positive electrode reveals greater and more stable performance for Zn–air battery (ZAB) than the benchmark catalysts (IrO2–Pt/C). This work opens an expressway for further investigation of the effect of material composition and synthesis conditions on electrocatalysis applications.