Tailoring the textural properties of hierarchical porous carbons for supercapacitors

•Hierarchical porous carbons (HPCs) are prepared by activation of humic acid.•The preparation of HPCs is simple comparing with template methods.•HPCs show unique pore size distribution: pores with the size of 1–2 nm and of 3–5 nm.•The textural properties can be tailored by changing the activation conditions.

Hierarchical porous carbons (HPCs) are prepared from humic acid by a simple KOH activation. HPCs show unique pore size distribution: abundant micropores with the size of 1–2 nm, mesopores with the size of 3–5 nm. Of special interest is the fact that the mesopore content with the size of 3–5 nm can be fine-tuned easily. HPCs show high performance for supercapacitors possessing of the optimized capacitance of 189 F g−1 in 3 M KOH with high capacitive retention. Furthermore, HPCs also exhibit a superior cycling stability, which can be attributed to the unique pore size distribution.

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