Flue‐Gas‐Derived Sulfur‐Doped Carbon with Enhanced Capacitance

Sulfur dioxide, generally coincident in CO2 sources, is a major air pollutant and causes inconvenient poisoning effects of catalysts in state‐of‐the‐art carbon capture and utilization (CCU) technologies. This study demonstrates an efficient strategy of directly capturing and in situ transforming flue gas into nanostructured sulfur‐doped carbon by molten salt electrolysis. The hazardous SO2 is fully captured and sulfur is utilized simultaneously. The obtained S‐doped carbon has ultrahigh surface‐area‐normalized capacitance of 71.5 µF cm−2, high gravimetric capacitance of 257.3 F g−1, excellent cycling stability, and good high‐rate capability. The process is realized in molten Li2CO3–Na2CO3–K2CO3–Li2SO4 at 475 °C armed with a nickel cathode and a SnO2 inert anode. This continuous‐operation process integrates carbon reduction, deep desulfurization, promising potential massive preparation of advanced carbon materials from practical waste gas without purification.