Electrochemical fabrication of polyRhodamine B film and Pt nanosheets on Ni foam for enhancing electrochemical detection activities of ammonia‑nitrogen

Accurate and rapid detection of ammonia nitrogen concentration has been become of great significance for protecting water resources and water resource restoration. Therefore, in this work, we intend to design one high-performance electrochemical sensor for ammonia‑nitrogen detection. Specifically, poly(Rhodamine B) film is electrodeposited on the surface of Ni foam via cyclic voltammetry technique, and then Pt nanosheets are electrodeposited on the surface of poly(Rhodamine B) film. The morphology and composition are characterized by ultraviolet-visible spectrophotometer, scanning electron microscope, X-rays diffractometry, X-ray photoelectron spectroscopy. The deposition process of poly (Rhodamine B) film and Pt nanosheets are controlled. The electrocatalytic measurements results of ammonia oxidation reaction indicate that the sample obtained with the cycle of 50 and the deposition time of 2000 s shows the biggest oxidation peak current with the value of 75.34 mA. Other electrocatalytic performances are also discussed. Furthermore, the electrochemical detection activities are measured and achieved a low limit of detection (1.182 μM) and high sensitivity (16.5 μA μM⁻¹), good recoveries in tap water, lake water and sea water, great selectivity and stability. Above great detection performances can be attributed to: 1) the introduction of poly (Rhodamine B) film effectively avoid the etch of Ni foam and provided one better platform for growth of Pt nanosheets, 2) more active sites are yielded owing to the sheet-like morphology of Pt.