Heterostructured NiO/IrO2 synergistic pair as durable trifunctional electrocatalysts towards water splitting and rechargeable zinc-air batteries: An experimental and theoretical study

Abstract

Constructing an ultra-durable trifunctional electrocatalyst with high efficiency for HER, OER and ORR has become critical for demanding water splitting and zinc air battery applications. Herein, we demonstrated a rational and efficient strategy to develop a porous nano foam like heterostructured NiO/IrO2 nano foam like electrocatalyst via a facile solvothermal and calcination approach. Experiments revealed that NiO/IrO2-NF shows outstanding HER (ƞ10=42mV), OER (ƞ10=240mV), and ORR (E1/2=0.80V) performances with lower overpotentials than many reported trifunctional electrocatalysts. Theoretical investigations on reaction mechanism of NiO/IrO2-NF, S-IrO2 and S-NiO were carried out using density functional theory calculations. The fabricated water electrolyzer required minimum cell voltage of 1.51V to reach 10mAcm-2 current density with outstanding durability of 600h and insignificant potential loss. Rechargeable zinc air battery with NiO/IrO2-NF air cathode displays a power density of 134.8mWcm-2 with excellent durability of 100/80/40h at 2/5/10mAcm-2.