Polyacrylamide hydrogel-derived three-dimensional hierarchical porous N,S co-doped carbon frameworks for electrochemical capacitors

Cost-effective porous carbon materials have been widely used in advanced electrochemical capacitors (ECs). Herein, we developed a simple yet scalable method to fabricate a porous hierarchical N,S co-doped carbon framework (HNSC-F) using a polyacrylamide hydrogel (PAAG) soaked with CH4N2S as a precursor. The HNSC-F is endowed with a large surface area of similar to 1192.1 m(2) g(-1), microporosity of similar to 91.8%, high surface wettability, and a high O content of similar to 8.4 at%, N similar to 5.3 at% and S similar to 0.8 at%. When evaluated as an electroactive material for ESs, the resulting HNSC-F electrode with a loading of 5 mg cm(-2) delivers a specific capacitance (SC) of similar to 254.4 F g(-1) in 6 M KOH, and even similar to 325.8 F g(-1) at 1 M H2SO4 at 0.5 A g(-1), owing to the extra heteroatom-involved faradaic reaction. Furthermore, the HNSC-F-based symmetric device with 6 M KOH exhibits a high energy density of similar to 10.3 W h kg(-1) at similar to 325.0 W kg(-1) within an operating window of an upper voltage limit of 1.3 V. Moreover, the symmetric ECs exhibit excellent SC retention with both alkaline (similar to 102.3%) and acidic (similar to 96.5%) electrolytes even after 5000 consecutive cycles. This promises the HNSC-F as a competitive electrode for advanced ECs.