Two-dimensional copper cobaltate nanosheets as an efficient bifunctional electrocatalyst for water splitting

Abstract Electrochemical water splitting is a promising strategy for sustainable hydrogen production; however, it requires efficient and durable non-noble metal electrocatalysts. In this work, we report the controlled synthesis of two-dimensional (2D) CuCo₂O₄ nanosheets (CC-NS) via a Triton X-100-assisted hydrothermal method, highlighting a morphology-engineering approach for enhanced bifunctional catalysis. The surfactant-directed growth enables the formation of a porous, ultrathin spinel architecture composed of nanocrystalline domains with uniformly distributed Cu and Co species. Structural and surface analyses (XRD, FESEM, TEM, EDS, and XPS) confirm a phase-pure cubic spinel structure with mixed-valence Co²⁺/Co³⁺ and Cu²⁺ states, which contribute to improved interfacial charge transfer and catalytic activity. In 1 M KOH, the CC-NS electrode delivers overpotentials of 280 mV for HER and 530 mV for OER at 50 mA cm⁻², demonstrating competitive bifunctional performance at relatively high current densities. The enhanced activity is attributed to the synergistic interplay between nanosheet morphology, porous structure, and mixed-metal redox chemistry. This study provides a rational design strategy for developing morphology-controlled spinel oxides as cost-effective electrocatalysts for alkaline water splitting.