A Multi-Interfacial Material Design Leading Bifunctional Oxygen Reduction and Water Oxidation Electrocatalysis to Zinc-Air Battery Application

The presence of an energy efficient and stable electrocatalyst capable of inflicting a bidirectional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is vital for the proper functioning of a rechargeable zinc-air battery (ZAB). Here, we rationally combined ORR-active nitrogen-doped graphitic carbon (N@C) around an OER-inflicting Ce-doped Ni-Co layered double hydroxide (LDH) to generate a unique N@C_LDH-CeO2 material, where all the segments operate synergistically to display bidirectional ORR/OER activity under analogous conditions. This multi-interfacial N@C_LDH-CeO2 material displayed exceptional energy efficiency, which was measured by its relatively low potential difference (ΔE) of 0.74 V between the half-wave potential of ORR (E1/2) and the OER potential at a current density of 10 mA cm-2 (Ej@10). This material was active in a ZAB assembly, achieving one of the highest reported specific energies (894.3 Wh kg-1 of Zn), appreciable power density (243 mW cm-2), and excellent specific capacity (698 mAh g-1 @ 10 mA cm-2), along with a remarkable durability of 270.0 h for 1600 continuous cycles. The tactical presence of N- and Ce-doping modulated the ORR and OER activity, respectively, as N@C_LDH-CeO2 displayed ample active sites during electrocatalysis on either side. This material remains active even in a solid-state ZAB assembly, where it successfully transduces energy to an electronic device.</p