Nitrogen and sulfur co-doped graphene nanoribbons: A novel metal-free catalyst for high performance electrochemical detection of 2, 4, 6-trinitrotoluene (TNT)

In this work, through a heteroatom-doping process and the subsequent base washing strategy, a new type of metal-free nitrogen- and sulfur-codoped graphene nanoribbons (BW-NS-rGONRs) were synthesized. It was found that a considerable amount of carbonaceous oxidative debris resided in graphene oxide nanoribbons (GONRs) produced from unzipping multiwalled carbon nanotubes has a great effect on the electrocatalytic activity of rGONRs. After removing the adsorbed oxidative debris by base washing, the obtained BW-NS-rGONRs exhibited high electrical conductivity and rich defect active sites, endowing the BW-NS-rGONRs enhanced electrocatalytic activity for TNT reduction. The electrochemical sensing platform established from the BW-NS-rGONRs showed a highly sensitive and selective response to TNT with a wide linear range from 0.0008 to 5.1 ppm and a detection limit of 0.1 ppb. Moreover, the BW-NS-rGONRs-based TNT detection platform demonstrated good cyclic stability and reproducibility. Most importantly, the BW-NS-rGONRs-based sensing platform can be successfully used for TNT determination in tap water and lake water samples. The superb sensing performance is attributed to the abundant active sites from dual doping of N and S atoms, the enhanced electrical conductivity and full exposure of the active sites of BW-NS-rGONRs after base washing treatment.

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