In situ template preparation of porous carbon materials that are derived from swine manure and have ordered hierarchical nanopore structures for energy storage.

Swine manure activated carbon (SMAC) was prepared by a simple in situ template method combining KOH activation with pyrolysis and using swine manure (SM) as a precursor. Natural metal oxides in SM are fully utilized as in situ templates instead of being removed. The effects of the in situ templates and the structural characteristics of the SMACs were studied via three contrasting strategies involving different pickling steps during pyrolysis and activation. The SMACs show excellent structural properties with specific surface areas of 876–2321 m2/g. The micropores size of all SMACs are concentrated at 0.5–0.6 nm; SMAC PHF has the most macropores (∼50 nm), and SMAC HF has more large macropores (∼100 nm) and mesopores (2–4 nm). These results should be attributed to CaO acting as a pore support, MgO catalyzing carbon decomposition and SiO 2 reaction promoting the activation effect. SMAC HF shows the best electrochemical performance with a specific capacitance of 278 F/g at 0.5 A/g and a high energy density of 24.62 Wh/kg at 450 W/kg for SMAC HF -based symmetric supercapacitors; the rate of retention is 96.2% after 10,000 cycles. This study provides a meaningful scheme for the low-cost and effective preparation of biomass carbon electrodes for supercapacitors. [Display omitted] • Swine manure activated carbon was prepared by an in situ template method. • Templates promoted activation and pore development. • Removing templates at different stages had distinct effects on the structure. • SMAC HF exhibited the largest SSA of 2321 m2/g. • At 0.5 A/g, SMAC HF had a maximum SC of 278 F/g with a 6 M KOH electrolyte. [ABSTRACT FROM AUTHOR]