Interconnected CoMoO4 rods with hierarchical cluster architecture for the superior electrochemical kinetics towards charge storage and HER performances

Abstract Herein, we report a facile approach for the synthesis of the interconnected CoMoO 4 rods with hierarchical clustered architectures and systematically explore their two-fold functionality as electrodes for the electrochemical charge storage and hydrogen evolution reaction (HER). The material exhibits mixed valence states (Co 2+ /Co 3+ and Mo 5+ /Mo 6+ ), which, together with the hierarchical structure, enhance electrochemical activity by improving charge transfer and providing abundant active sites. Kinetic analysis based on Dunn’s and Trasatti’s methods reveals the combined contributions of surface capacitive and diffusion-controlled processes in the overall charge storage mechanism. The assembled symmetric device delivers a high specific capacity of 230 C g −1 at 1 A g −1 within an extended potential window of 1.6 V and retains 92% of its initial capacity after 5000 cycles. The device achieves a maximum specific energy of 51 Wh kg −1 and a maximum power density of 42 kW kg −1 , demonstrating favorable energy–power characteristics. In addition, the CoMoO 4 electrode exhibits efficient HER performance with a low overpotential of 184 mV at 20 mA cm −2 , a Tafel slope of 108 mV dec −1 , and excellent stability over 72 h of continuous operation. The enhanced performance is attributed to the synergistic effect of hierarchical morphology, mixed valence states, and defect-rich structure, which facilitate efficient electron transport and ion diffusion. These results highlight the potential of CoMoO 4 as a promising electrode material for integrated energy storage and conversion applications.