Single-atom palladium on nonstoichiometric tungsten oxide as bifunctional electrocatalyst for zinc-air battery

Searching for an excellent bifunctional electrocatalyst used in zinc-air batteries (ZABs) is a long-term and challenging task. Single-atom catalysts have been becoming potential bifunctional electrocatalysts because of their maximum metal atom utilization and low content of metal itself. Herein, noble metal palladium (Pd) is uniformly anchored in the supported WO2.72 to form single-atom Pd/WO2.72 owing to the special 4d orbit of Pd and nonstoichiometric 2D planar structure of WO2.72. Single-atom 5 % Pd/WO2.72 is prepared in this work, showing excellent bifunctional electrocatalytic behaviors with high E1/2 of 0.86 V for ORR and low Ej=10 of 1.59 V for OER in alkaline medium, and the ∆E is 0.73 V, which outperforms the Pt/C and RuO2. Furthermore, the 5 % Pd/WO2.72-ZAB has a high open-circuit voltage (OCV) value of 1.491 V, a large power density of 168 mW cm−2, and a large specific capacity of 633 mAh g−1. Besides, the 5 % Pd/WO2.72-ZAB also has good cycling stability.