Synthesis of Three-Dimensional Hierarchically Porous Carbon Monolith via “Pyrolysis-Capture” Strategy for Supercapacitors

Carbon monolith is of particularly great interest in electrochemical applications due to its high surface area, controllable morphology and excellent electronic conductivity. Herein, a novel three-dimensional hierarchically porous carbon monolith (TD-HPCM) was synthesized by a "pyrolysis-capture" strategy. The commercial polyurethane (PU) foam concurrently acted as a template and carbon precursor. Carbonaceous organic gas pyrolyzed from PU foam was captured by mesoporous silica which coated on the branches of PU foam uniformly then converted into carbon under catalysis of Ni species at high temperature. The geometric shape and interconnected network of PU foam were preserved in TD-HPCM, with a large specific surface area (1111 m2 g−1) and uniform mesoporous size (6.7 nm). The TD-HPCM was explored as binder-free electrode in supercapacitors, with capacitance up to 162 F g−1 at 1.0 A g−1 in 6 M KOH electrolyte and favorable capacitance retention (92.7% capacitive retention after 5000 cycles). This strategy provides a controllable, energy efficient and highly repeatable method to prepare TD-HPCM with micro/meso/macroporous structures as binder-free electrodes in electrical double layer capacitors.