High Performance Core–Shell Structured ZnCo₂O₄ Nanosheets@Co₃O₄ Nanowires for Overall Water Splitting

Abstract

In this study, a ZnCo 2 O 4 @Co 3 O 4 composite material with a core–shell structure was synthesized using a hydrothermal method followed by calcination, and its electrocatalytic performance for overall water splitting was systematically investigated. The composite material, consisting of Co 3 O 4 nanowires grown on ZnCo 2 O 4 nanosheets, exhibited an enhanced surface area and improved electron transfer pathways, which significantly increased the number of active sites. For the hydrogen evolution reaction (HER), the composite displayed a low overpotential of 181.5 mV and a favorable Tafel slope of 146.37 mV dec −1 . For the oxygen evolution reaction (OER), it demonstrated an overpotential as low as 169.3 mV with a Tafel slope of 78.5 mV dec −1 . Furthermore, the ZnCo 2 O 4 @Co 3 O 4 composite exhibited excellent stability, retaining 83% of its initial current density after 12 hours of continuous operation. These results suggest that the ZnCo 2 O 4 @Co 3 O 4 composite is a promising and efficient catalyst for overall water splitting, offering a cost-effective solution for sustainable hydrogen production.