Electrodeposited NiCu bimetal on carbon paper as stable non-noble anode for efficient electrooxidation of ammonia

Abstract

Electrochemical remediation of ammonia-containing wastewater at low cell voltage is an energy-effective technology which can simultaneously recover energy via hydrogen evolution reaction. One of the main challenges is to identify a robust, highly active and inexpensive anode for ammonia electrooxidation. Here we present an alternative anode, prepared by electrochemical co-deposition of Ni and Cu onto carbon paper. This NiCu bimetallic catalyst is characterised by scanning electron microscope, scanning transmission electron microscope, X-ray diffraction, x-ray photoelelectron spectroscopy, cyclic voltammetry, linear sweep voltammetry and chronoamperometry techniques. The stability and activity of NiCu bimetallic catalyst are largely improved in comparison with Ni or Cu catalyst. Moreover this noble-metal-free NiCu catalyst even performs better than Pt/C catalyst, as NiCu is not poisoned by ammonia. An ammonia electrolysis cell is fabricated with NiCu/carbon paper as anode for ammonia electrolysis. The influences of pH value, applied cell voltages and initial ammonia concentration on cell current density, ammonia removal and energy efficiency are tested. An ammonia removal efficiency of ∼80% and coulombic efficiency up to ∼92% have been achieved. Ni-Cu bimetal on carbon paper is a stable non-noble anode for efficient electrooxidation of ammonia.