Synergistic H^* Generation and Substrate Adsorption Drives Efficient Electrocatalytic Hydrogenation of 4-Nitrophenol...

As a prevalent and highly hazardous organic contaminant in wastewater, the removal of 4-nitrophenol (4-NP) from the environment is of utmost urgency. Recently, electrocatalytic 4-NP hydrogenation has been considered as an environmentally friendly strategy, which can not only remove 4-NP from wastewater but also produce high-value-added product 4-aminophenol (4-AP). However, the electrocatalysis method still faces the challenge of low efficiency and the addition of reducing agents (e.g., H₂ and NaBH₄). Herein, a cooperative Ag/polydopamine catalyst was prepared by in situ immobilization of Ag nanoparticles on polydopamine (Ag/PDA), showing high electrocatalytic 4-NP to 4-AP performance with Faradaic efficiency (FE) of 98.4% and 4-AP selectivity of 99.6%. Experimental results and theoretical calculations reveal that PDA can enhance the adsorption of 4-NP ions and promote the generation and capture of reactive hydrogen species (H^*), enabling high reaction rate and selectivity. Moreover, PDA can also disperse and stabilize Ag nanoparticles on the catalyst. Finally, we design an integrated system of electrocatalytic 4-NP hydrogenation coupled with glycerol oxidation, achieving the co-production of 4-AP and formate, further improving the economic efficiency of the system.