Interface-Tailored MWCNT@WO₃/NiCo₂O₄ Heterostructure Electrocatalyst for High-Performance Oxygen Evolution Reaction

The half reaction of oxygen evolution reaction (OER) has slow kinetics compared to the other reactions of hydrogen evolution reaction (HER) in electrocatalyst-based water splitting (WS) for hydrogen production. To improve the WS by an electrocatalyst, the use of spinel oxide based heterostructure (HS) catalysts supported by a carbon material is considered as a cost-effective strategy for the application of OER over noble metal catalysts. Here, for the first time, a novel WO₃/NiCo₂O₄ heterostructure coupled with MWCNT was synergistically interface engineered via an ultrasonication-assisted hydrothermal synthesis method to achieve an efficient electrocatalyst based oxygen evolution reaction (OER) due to their significant electrochemical activity of HS. The rational integration of WO₃ and redox-active NiCo₂O₄ with the highly conductive MWCNT framework results in a hierarchically porous heterointerface that promotes improved charge carrier transport, enhanced active site accessibility, and synergistic conductivity. The electrochemical results demonstrate the reduced overpotential of 323 mV at 10 mA cm^-2 for MWCNT@WO₃/NiCo₂O₄ with a Tafel slope of 123 mV dec^-1, a reduced charge transfer resistance of 2.5 Ω, and a large electrochemical double-layer capacitance of 48.9 mF cm^-2, outperforming its individual and WO₃/NiCo₂O₄ counterparts. Improved reaction kinetics, reduced energy barriers, and superior electrochemical durability of over 38 h underscore the effectiveness of this interface engineering strategy. These findings highlight the promise of MWCNT@WO₃/NiCo₂O₄ as a cost-effective, high-performance heterostructure for OER electrocatalysis in integrated water splitting and sustainable oxygen evolution reactions.