Towards highly exposed active sites via Edge-N-rich carbon nanosheet @ porous biochar for efficient H2S catalytic oxidation

In this study, Edge-N-rich carbon nanosheet @ porous biochar (NCN@PB) was synthesized successfully from waste biomass self-assembly in a simple and green approach. The accessible and efficient utilization of edge-N enriched on the surface, together with the hybrid structure of NCN@PB improved the H2S oxidation capacity up to 390.1 mg/g at room temperature, reflecting an 8-fold enhancement compared with the blank biochar. The Density functional theory calculation, in-situ DRIFTS, and the characterization results further uncovered the desulfurization mechanism of active sites. Edge-N species decreased the barriers in critical steps governing H2S catalytic oxidation, i.e., H2S dissociation and O-2 activation, especially the pyrrolic N. This strategy is beneficial for the development of surface engineering on metal-free catalysts and provides a new idea for improving the catalytic combustion activity of N-doped biochar.