Integrated experimental, first-principles study, and machine learning investigation of thermally optimized CoMoO for supercapacitors

Abstract

The precise control of crystallinity and electronic structure in transition-metal molybdates is still a fundamental challenge in the development of high-performance supercapacitor electrodes. We herein report a dwell-time modulated thermal decomposition strategy to achieve phase-pure CoMoO4 with tuneable crystallinity-electronic structure coupling for advanced energy storage applications. Among the synthesised samples, CM3 showed an optimised monoclinic phase with reduced microstrain and a vertically oriented nanosheet morphology, allowing rapid ion diffusion and better electrochemical accessibility. Density functional theory calculations revealed vacancy-induced Co 3d–Mo 4d–O 2p orbital hybridisation, which promoted charge delocalisation near the Fermi level and accelerated charge-transfer kinetics. Benefiting from these synergistic structural and electronic features, the CM3 electrode delivered a high specific capacitance of 545.94 F g−1 at 1 A g−1 with 93.28% capacitance retention after 10 000 cycles. Furthermore, the assembled asymmetric CoMoO4//AC supercapacitor achieved a wide operating voltage window of 1.8 V and a high energy density of 64.74 Wh kg−1 with excellent cycling stability. The device also demonstrated practical feasibility by powering a real-time RGB sensing platform. In addition, a physics-informed Random Forest model exhibited strong predictive accuracy across electrochemical datasets, highlighting the potential of integrating data-driven modelling with experimental materials design.