Synergistically enhanced atomically dispersed Fe-Nx sites on carbon nanotubes by heteroatom S to boost electrochemical oxygen reduction for microbial fuel cell

Fuel cells require efficient and durable electrocatalysts to improve oxygen reduction reactions (ORR) to mitigate the current energy crisis. However, unsatisfactory catalytic activity and stability caused by slow kinetics and mass transport characteristics restrict the further development of fuel cells. Here, a preparation strategy is proposed for manufacturing iron single-atom catalyst modified by sulfur doping dispersed over nitrogen-doped carbon nanotubes (NCNTs@Fe-NSC). Both experimental theoretical results prove that legitimately engineered substitution doping of coordination structure can effectively regulate charge balance of centers to optimize the adsorption and desorption energy of oxygen-containing intermediates and improve the activation energy barrier of elementary reaction. The NCNTs@Fe-NSC achieves astonishing ORR capacity and satisfactory electrocatalytic stability with a loss of activity about 2.4 % after 60 h, including poison resistance, in neutral electrolyte. This study provides a perspicacious thought for rational design of single atom catalysts using element doping engineering to achieve high efficiency electrocatalysis.