Highly Efficient Acidic Electrosynthesis of Hydrogen Peroxide in Air-Fed Conditions Accelerated by a Three-Dimensional Cross-Linked Carbon Nanoweb Catalyst

Electrosynthesis of hydrogen peroxide (H₂O₂) via a two-electron oxygen reduction reaction (2e^– ORR) provides a green and sustainable alternative to the current energy-intensive anthraquinone process. However, the development of inexpensive and efficient electrocatalysts under acidic and air-fed conditions remains a challenge. Herein, we constructed a three-dimensional nitrogen-doped carbon nanoweb (3D-N-CNW) electrocatalyst by using a naturally porous cross-linked skeleton of water hyacinth as a raw material. The 3D-N-CNW shows an ultrahigh specific surface area of 1464 m² g^–1 with interconnected hierarchical porous architecture, and abundant carbon defects, resulting in excellent 2e^– ORR activity with high onset potential (0.64 V) and H₂O₂ selectivity (∼93%), which is the best-performing carbon-based catalyst reported in acidic media. Impressively, the flow cell utilizing 3D-N-CNW achieves an exceptionally high H₂O₂ yield of 4289 mg L^–1 h^–1 under air self-breathing conditions, enabling ultrafast degradation of representative organic pollutants. Theoretical calculations and control experiments reveal that the 3D cross-linked network facilitates mass transport and creates an enriched O₂ microenvironment to promote the 2e^– ORR to highly efficient H₂O₂ production. This work provides a low-cost, readily scalable, and convenient route for the construction of advanced carbon-based electrocatalysts from natural biomass materials; it can also be expected in other renewable areas.