In situ grown cobalt-doped nickel–molybdenum bimetallic phosphide nanonet on carbon cloth for high cycling stability flexible supercapacitors

Abstract

This study aims to investigate the influence of Co introduction on the electrochemical performance of nickel–molybdenum bimetallic phosphides grown in situ on carbon cloth (NiMoP/CC) and to optimize the Co content to enhance their suitability for flexible supercapacitor applications. Although NiMoP possesses high specific capacitance, its poor cycling stability limits its practical application. To address this issue, Co ions were doped into NiMoP, significantly enhancing its electrochemical durability. The optimized Co-NiMoP/CC-2 composite achieved a high specific areal capacitance of 1675 mF cm⁻² and retained 84.56% of its capacitance after 40 000 charge–discharge cycles, far superior to that of pristine NiMoP/CC. Furthermore, a flexible asymmetric supercapacitor (FASC) was assembled using Co-NiMoP/CC-2 as the cathode, which exhibited excellent cycling stability, retaining 70.34% of its capacitance even after 100 000 charge–discharge cycles. The device also demonstrated good mechanical flexibility, retaining stable performance under dynamic deformation and being capable of powering a light-emitting diode (LED) and an electronic clock. Moreover, DFT calculations further elucidate the influence of Co doping on the Ni–Mo bimetallic phosphide. Overall, this work highlights the great potential of Co-NiMoP/CC composites for flexible supercapacitors and provides an effective strategy to address the durability issue of NiMoP-based electrodes during long-term cycling through controlled Co introduction.