Dual-functionality of NiSe₂-CoSe₂ nanowires for electrochemical charge storage and efficient thermal energy conversion

Thermo-electrochemical cell coupled with an electrochemical energy storage device creates a comprehensive harvesting system that can convert thermal energy into electrical energy and store it. Thus, the development of electrodes that demonstrate high efficiencies in electrochemical and thermoelectric properties is crucial, as they serve as the fundamental components in energy conversion and storage systems. This study presents the synthesis of NiSe₂-CoSe₂ (NCS) nanowires on activated carbon cloth (ACC) substrate, for enhanced electrochemical charge storage and ionic-thermoelectric applications. Comparative analysis demonstrates that NCS/ACC electrodes significantly outperform monometallic selenides in both electrochemical performance and thermoelectric applications. The NCS/ACC electrode revealed a maximum charge storage capacity of 112 mA hg⁻¹ at a current density of 1 A g⁻¹. Utilizing 1 M NaOH as an aqueous electrolyte, the NCS/ACC system showcases its pioneering role in thermo-electrochemical cell (TEC), opening avenues for efficient heat-to-electricity conversion. The NCS/ACC-based TEC delivered a Seebeck coefficient of −3.4 mV K⁻¹ and thermal charge storage of −1.02 J. These findings reveal the dual functionality of nickel cobalt selenides, offering promising solutions for thermal energy harvesting and storage in electrochemical systems.