Fabrication of efficient and robust Fe0/Ni2P/CC composite and the employment for electrochemical reduction of nitrate

Abstract

The process of electrochemical nitrate reduction behaving the merits of sufficient efficacy and environmental benignity has attracted immense interest for the nitrate (NO3-) disposal. However, the practical application of this technique is seriously restricted due to the defects of generating by-products (such as ammonium and nitrite), and the presence of total nitrogen (TN) with a high concentration. In this work, a novel catalyst composite (Fe0/Ni2P/CC) was fabricated via the combined method involving liquid-phase reduction, electroless nickel-phosphorus plating and phosphation processes. The crystal structure, morphology, and chemical component of the obtained composite were characterized. The influences of operating parameters (pH value, current density, initial nitrate-N concentration and coexisting substances) on the NO3- reduction were assessed. At the optimized conditions, the synthesized Fe0/Ni2P/CC composite displays the fascinating performances in NO3- conversion (89.81%), N2 selectivity (95.55%) and tested endurance, comparing with other three samples (i.e. Fe0 +Ni2P/CC, pure HER and pure Fe0). For the disposal for simulated effluent of municipal wastewater treatment plant effluent, this composite exhibits a superb NO3- conversion of 89.81%, and the concentration of TN (1.92 mg L−1) is lower than the threshold limit (2 mg L−1) of five-level standard for surface water of China. It is noteworthy that the Fe0/Ni2P/CC composite has an excellent durability (< 5% decay after 20 h reduction test), and the spent sample can be employed for the decoloring of methyl orange via the chemical advanced oxidation process (95% for decolorization efficiency).