Hierarchically porous biochar for supercapacitor and electrochemical H₂O₂ production

Although biochar is widely recognized as a multifunctional material, developing high-performance carbon materials from biochar for both energy and environmental applications remains challenging. In this work, torreya grandis inner-shell, a widespread lignocellulosic biomass waste, was used to synthesize hierarchically porous carbon materials via a designed carbonization/activation approach. The prepared biochar exhibited excellent energy storage performance in 1 M Na₂SO₄ with a large capacitance, high-rate capability, and favorable stability (97% capacitance retention after 5000 cycles). The fabricated carbon materials also exhibited good catalytic activity toward electrosynthesis of hydrogen peroxide from oxygen reduction. The production of H₂O₂ was as high as 61.3 mg L⁻¹h⁻¹ at −0.6 V and pH 3.0, which was used for efficient degradation of organic pollutants (rhodamine B and phenol) in an electro-Fenton system. This work provides an efficient and low-cost approach for the carbonization/activation of waste biomass to obtain the hierarchical porous biochar for clean energy storage and environmental application.