Isolation of cobalt single atoms on hollow B, N co-doped defective carbon nanotubes for hydrogen peroxide production and tandem reagent-free electro-Fenton oxidation

Single-atom catalysts (SACs) have been at the leading edge of catalytic research, but are still challenging to choose appropriate substrates and single-atom configurations with desirable activity and selectivity. Herein, we propose a nanotube reactor strategy with Co-SACs confined into B,N co-doped defective carbon nanotubes (Co-B, N-CNTs) via a spatial isolation and dopant anchoring strategy. The Co-B,N-CNTs exhibited excellent activity and selectivity for H2O2 production via a two-electron oxygen reduction reaction (ORR) pathway with a high yield of 1508 mmol L-1 gcat  1 in HClO4. The excellent electrocatalytic performance of Co-B,N-CNTs was mainly due to the uniformly dispersed Co-SACs with defect-rich active sites, appropriate regulated electronic structure with different electronegative atoms' modification and favorable 3D hollow nanotube structure. Moreover, the on-situ H2O2 generation remarkably accelerated various organic pollutants degradation and Cr (IV) detoxification via a reagent-free double-cathode electro-Fenton process. This work sheds light on the design of multi-functional catalysts for the sustainable production of valuable chemicals and the innovation of new-generation wastewater treatment technology.

Automated summary

Single-atom catalysts (SACs) are challenging to choose the right substrates and configurations. This study introduces a nanotube reactor strategy to confine Co-SACs in B,N co-doped defective carbon nanotubes (Co-B,N-CNTs) through spatial isolation and dopant anchoring. The Co-B,N-CNTs demonstrated excellent activity and selectivity for H2O2 production via a two-electron oxygen reduction reaction (ORR) pathway, with a high yield of 1508 mmol L-1 gcat-1 in HClO4. The outstanding electrocatalytic performance of Co-B,N-CNTs is attributed to the uniformly dispersed Co-SACs, defect-rich active sites, regulated electronic structure, and favorable 3D hollow nanotube structure. Furthermore, the in-situ generation of H2O2 significantly accelerated the degradation of organic pollutants and Cr (IV) detoxification through a reagent-free double-cathode electro-Fenton process. This work provides insights into the design of multi-functional catalysts for sustainable chemical production and innovative wastewater treatment technology.