Preparation Of Carbon Cloth-supported Polypyrrole/Platinum Nickel Alloy Composite Electrode And Its Ammonia-nitrogen Sensitivity

Ammonia nitrogen is one of the main pollutants in water,which has a toxic effect on aquatic organisms and causes damage to aquatic ecosystems.Excessive ammonia nitrogen will also threaten the safety of human drinking water.Therefore,accurate detection and monitoring of ammonia nitrogen in water is very important.As a method of ammonia nitrogen detection,the electrochemical method is gradually paid attention by researchers.Among them,the nano-material modified electrode method has the advantages of direct and high efficiency.It is the main goal of the researchers to prepare an ammonia nitrogen sensitive electrode with high sensitivity and good selectivity.Based on the excellent catalytic activity for ammonia electrooxidation,precious metal Pt and its alloys have attracted the attention of researchers as ammonia-nitrogen-sensitive electrodes.However,there are few reports about the use of Pt-non-noble metal alloys as sensitive materials for the detection of ammonia nitrogen in water.Therefore,this article innovatively uses PtNi alloy as the ammonia-nitrogen-sensitive material,adopts inert carbon cloth as the substrate,introduces polypyrrole?PPy?as the intermediate layer,prepares the ammonia-nitrogen-sensitive electrode,and optimizes the preparation conditions to obtain the ammonia-nitrogen-sensitive material with good sensitivity characteristics electrode The specific research contents are as follows:First,PtNi was used as the ammonia-nitrogen sensitive material,and the PtNi material was deposited on the carbon cloth by electrodeposition to prepare a carbon cloth substrate/platinum nickel alloy?CC-PtNi?sensitive electrode.It was observed by scanning electron microscope?SEM?that the PtNi material was composed of flakes and strips.The formation of PtNi alloy was confirmed by X-ray diffraction?XRD?analysis of the crystal structure of the material.The effects of the molar concentration ratio of H₂PtCl₆ and NiSO₄ in the electrodeposition precursor solution,the number of cycles,the cycle rate,and the PPy deposition time during the electrochemical deposition process on the ammonia-nitrogen sensitivity of the sensitive electrode were optimized.The preparation conditions were optimized.The sensitivity to ammonia nitrogen in the concentration range of 1-40?M is 0.024 mA cm^-2?M^-1,the linearity is0.99,and the detection limit is 0.6?M.Compared with the carbon cloth substrate/platinum?CC-Pt?sensitive electrode(sensitivity:0.016 mA cm^-2?M^-1)prepared under exactly the same conditions,the sensitivity is increased by one third,indicating that the alloying of Pt is sensitive The ammonia nitrogen sensitivity of the electrode has been improved.Compared with the ammonia-nitrogen sensitivity of the sensitive electrode reported in the literature,it can be found that the prepared CC-PtNi sensitive electrode has better sensitivity and linearity.On the basis of the above research,we introduced PPy as an intermediate layer,and composited PPy with PtNi materials to prepare CC@PPy-PtNi sensitive electrodes.Firstly,PPy was electrochemically deposited on the carbon cloth,and then the PtNi alloy was deposited.The prepared sensitive electrode was characterized by SEM,XRD,XPS,which proved that the PtNi deposited on the PPy layer existed in the form of alloy.Subsequently,the effects of PPy deposition parameters,the ratio of PtNi in the precursor,and the number of cycles on the ammonia nitrogen sensitivity characteristics of the CC@PPy-PtNi sensitive electrode were analyzed,and the preparation conditions were optimized.The optimized electrode has a sensitivity of 0.03 mA cm^-2?M^-1,a detection limit of 0.63?M,and a linearity of 0.99 in the range of 1-40?M.It also has good selectivity.Studies have shown that the introduction of PPy not only reduces the contact resistance,but also improves the ammonia-nitrogen sensitivity of the sensitive electrode.Compared with the ammonia-nitrogen sensitivity characteristics of the sensitive electrodes reported in the literature,the prepared CC@PPy-Pt Ni sensitive electrode has higher sensitivity and lower detection limit,indicating that the sensitive electrode we prepared has good ammonia-nitrogen sensitivity characteristics.In summary,this article innovatively uses PtNi alloy as the ammonia nitrogen sensitive material,carbon cloth as the substrate,and introduces PPy as the intermediate layer to prepare the ammonia nitrogen sensitive electrode.Using the synergy between Pt and Ni and PtNi alloy and PPy to improve the ammonia-nitrogen sensitivity of the sensitive electrode,the ammonia-nitrogen sensitivity of the sensitive electrode provides a new idea for the development of electrochemical ammonia-nitrogen sensors.