In situ and one-step electrodeposition growth of PtNi alloys on Ni foam for electrochemical ammonia-nitrogen sensing

Abstract

The presence of ammonia-nitrogen in aquatic ecosystems has recently been recognized as a significant threat to public and ecological health. Hence, it is crucial to develop a reliable method for accurately quantifying low levels of this pollutant in the aquatic environment. In this work, PtNi alloys of varying compositions were fabricated via a one-step in-situ electrodeposition process on a Ni foam surface. The electrochemical catalytic performances for the ammonia oxidation reaction have been measured via the cyclic voltammetry (CV) technique. The experimental results demonstrated that the PtNi alloy exhibited the highest catalytic capability with the current density of 21.387 mA cm−2 for the ammonia oxidation reaction, when the ratio of H2PtCl6·6 H2O and Ni(NO3)2·6 H2O was 3:1 with the deposition time of 1500 s. Under the most favorable conditions, the electrochemical detection performance of the PtNi alloy in detecting ammonia-nitrogen has been extensively assessed based on the differential pulse voltammetry (DPV) technique. The experiments confirmed that the PtNi alloy demonstrated an outstanding sensitivity, reaching a remarkable value of 0.0255 mA µM−1, with a broad linear range from 3 µM to 500 µM. The PtNi alloy also demonstrated a remarkable low limit detection of 0.89 µM. In addition, Further evaluation of the anti-interference ability, reproducibility, stability and recovery in real sample analysis including tap water, lake water and sea water revealed that the PtNi alloy exhibited superior performance for detecting ammonia-nitrogen.