Electrochemically-mediated capture and reduction of Cr(VI) by highly porous N-doped carbon spheres

N dopping can enhance the electrochemical efficiency of carbon materials, but the effect of N on the electrochemical-mediated removal of Cr(VI) has been mostly ignored. Here, we report highly porous N-doped carbon spheres for electrochemical-mediated removal of Cr(VI), and the role of N on Cr(VI) removal has been systematically investigated using both experimental evaluations and theoretical validation. Experimental findings revealed that the removal capacity of Cr(VI) reached 186.5 mg·g−1 with a removal rate of 100%. In addition, the underlying processes for the role of N species have been investigated using density functional theory (DFT) calculations. The result agrees with the findings from the experimental evaluations thus suggesting that the removal process of Cr(VI) was mainly distributed by pyridinic-N and oxidized-N. This study has demonstrated that the removal of Cr(VI) by N species forms a crucial part in the removal of Cr(VI) using N-doped carbon materials and offers a possible alternative approach for enhancing the removal efficiency of carbon materials.