Oxygen functionalization‐assisted anionic exchange toward unique construction of flower‐like transition metal chalcogenide embedded carbon fabric for ultra‐long life flexible energy storage and conversion

The metal‐organic framework (MOF) derived Ni–Co–C–N composite alloys (NiCCZ) were “embedded” inside the carbon cloth (CC) strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application. The NiCCZ was then oxygen functionalized, facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization, generating a flower‐like metal hydroxysulfide structure (NiCCZOS) with strong partial implantation inside CC. Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three‐electrode configuration. Moreover, when paired with the biomass‐derived nitrogen‐rich activated carbon, the asymmetric supercapacitor device shows almost 100% capacity retention even after 45,000 charge–discharge cycles with remarkable energy density (59.4 Wh kg–1/263.8 µWh cm–2) owing to a uniquely designed cathode. Furthermore, the same electrode performed as an excellent bifunctional water‐splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction (OER) and 168.4 mV for hydrogen evolution reaction (HER) at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER. Hence, a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications. The electrocatalyst embedded inside the conductive carbon fabric followed by the oxygen functionalization‐supported stoichiometric sulfurization gave an ultra‐stable performance for the supercapacitor and hydrogen evolution reaction and oxygen evolution reaction stability test as compared to the traditional self‐grown electrocatalysts owing to the robust electrocatalyst attachment to the current collector, further facilitating superior ion/electron mobility.