Electrochemical hydrogenation detoxication of p-nitrophenol via self-supported rGO/CoP/CF electrode: Performance, mechanism and biotoxicity

Electrochemical hydrogenation detoxication (EHD) has been emerged as a sustainable technology to eliminate biotoxicity of p-nitrophenol (PNP). Although cobalt (Co) compounds-based electrodes have attracted intensive attention in EHD of PNP, the obstacles such as restricted electron transfer efficiency and atomic hydrogen (H*) generation efficiency have not been solved yet. In this work, a self-supported rGO/CoP/CF electrode was fabricated via direct growth of needle-like cobalt phosphide (CoP) on cobalt foam (CF) followed by in-situ rGO electrodeposition. The rGO/CoP/CF electrode exhibited high activity for electrochemical PNP detoxication, with 91.5% of p-nitrophenol (10 mg L-1) removed within 40 min at 20 mA. The self-supported needle-like CoP and rGO not only provided abundant active sites but also accelerated electron transfer and H* generation and uti-lization for PNP reduction. Both experimental results and density functional theory (DFT) calculations demon-strated a low energy barrier of potential determining step (PDS) on rGO/CoP/CF, which was beneficial to PNP reduction by the direct electron transfer and indirect H*. The rGO/CoP/CF showed excellent electrochemical activity during 20th cyclic experiments and in real water. Furthermore, the toxicity test based on the viability of E. coli DH5 alpha demonstrated the efficient detoxication of PNP via rGO/CoP/CF cathode reduction. These findings suggest that the resulting electrode is promising for electrocatalytic reduction of refractory pollutants in water.

Automated summary

Electrochemical hydrogenation detoxication (EHD) is a sustainable technology for eliminating biotoxicity of p-nitrophenol (PNP). However, current Co-based electrodes face challenges in electron transfer efficiency and atomic hydrogen generation. In this study, a self-supported rGO/CoP/CF electrode was developed, which exhibited high activity for electrochemical PNP detoxication and showed excellent electrochemical activity in real water. This electrode holds promise for catalytic reduction of refractory pollutants in water.