Hollow NH2-MIL-101@TA derived electrocatalyst for enhanced oxygen reduction reaction and oxygen evolution reaction

Abstract Non-precious metal-based electrocatalysts with excellent activity and stability are highly desired for the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a tannic acid (TA) etching strategy is used to inhibit the metal aggregation and achieve muti-metal doping. The hollow NH2-MIL-101@TA derived Fe–N–C catalyst exhibits superior ORR catalytic activity with an E1/2 of 0.872 V and a maximum output power density of 123.4 mW cm−2 in Zn-air battery. Since TA can easily chelate with metal ions, Fe/Co–N–C and Fe/Ni–N–C are also synthesized. Fe/Ni–N–C manifests exceptional bifunctional activity with an Ej = 10 of 1.67 V and a potential gap of 0.833 V between Ej = 10 and E1/2 in alkaline electrolyte, which is 45 mV smaller than Pt/C–IrO2. The improvement of ORR and OER performance of the catalysts via the simple TA etching and chelation method provides a novel strategy for the design and synthesis of efficient electrocatalysts.