Leather waste as precursor to prepare bifunctional catalyst for alkaline and neutral zinc-air batteries

Carbon materials derived from biomass waste are considered as potential electrocatalysts for applications in zinc-air batteries (ZABs) due to their low cost and good catalytic activity. Here, we reported the preparation of gel-based catalysts through utilizing hydrolyzed waste leather powder cross-linked with metallic salt solutions. After calcination, iron-nickel alloy anchored in nitrogen-doped porous carbon catalysts (FeNi@NDC) was achieved. Compared with commercial Pt/C catalyst, FeNi@NDC-800 exhibited lower E_1/2 (0.77 V) and better durability. More importantly, the resulting FeNi@NDC-800-based alkaline ZABs achieved power density of 93.01 mW/cm² and open circuit voltage of 1.45 V, which the FeNi@NDC-800-based neutral ZAB displayed a charge/discharge cycle stability of 275 h. This work opens up the possibility of rational design and preparation of low-cost and high-performance electrocatalysts from recyclable leather waste.