A green trace K2CO3 induced catalytic activation strategy for developing coal-converted activated carbon as advanced candidate for CO2 adsorption and supercapacitors

[Display omitted] •A green K2CO3 catalytic activation is developed for preparing activated carbon.•Potassium based catalytic component can be regenerated in activation process.•Ca_AC_1 exhibits excellent CO2 adsorption capacity and stability.•Ca_AC_1 organic supercapacitor exhibits energy density up to 35.7 Wh/kg.•The strategy can be readily amplified based existing physical activation craft. Aiming to enhancing porosity development and reducing the dosage of activation agents in preparation of activated carbon, a novel green and efficient strategy of trace K2CO3 induced catalytic activation was proposed. In the design, adding small amount of K2CO3 (less than 2% weight ratio of precursor) can significantly reduce the reaction barrier between coal framework and CO2 molecules, thus enhancing pore formation of as-obtained activated carbons. The resulting Ca_AC-1 has short range ordered microcrystalline structure and developed pore structure, even superior to the activated carbon from chemical activation with large dosage of K2CO3 (three times weight ratio of carbon precursor). Evaluated as CO2 adsorbent, Ca_AC-1 a high CO2 adsorption capacity and adsorption-regeneration cycling stability. More importantly, Ca_AC-1 with optimized pore and crystalline structure can deliver excellent supercapacitive performances in term of high energy and power densities (26–35 Wh/kg at 0.338–6.25 kW/kg in organic system) as well as 100% cycling stability. Both experiment and density functional theory (DFT) calculations demonstrate that C-O-K structure can be regenerated in CO2 activation, leading to continuously catalytic effects despite low-dose K2CO3 addition. Combining the low-cost sources, simple preparation procedures and good application performances, the resulting activated carbon holds great potentials for scalable production and applications. Such strategy can also be extented for developing high-performance activated carbons from various kinds of solid carbon sources.