Preparation And Properties Of Hydrazine Electrochemical Sensor Based On Antimony Sulfide And Its Composite Film

Hydrazine（N₂H₄?H₂O）is an important chemical raw material that can be used in many fields of life such as pesticides,medicines,dyes,fuel cells and explosives.Although it is important for people,it also shows certain harmfulness,especially as a neurotoxin,even at very low levels,it can result in the health problems,so it is necessary to detect its content in the environment.Hydrazine electrochemical sensors with low cost and high sensitivity,have attracted great attentions.The choice of the modified electrode material is a key factor affecting the performance of the electrochemical sensor.As an electrochemical sensor,Antimony sulfide（Sb₂S₃）is an important anisotropic semiconductor widely used in solar cells,photocatalysis,etc.However,research on hydrazine detection has rarely been reported.In this work,Sb₂S₃ and its composite film were obtained by electrochemical deposition and heat treatment process.The electrochemical sensors were prepared by modifying different conductive substrates,and the detection performance was tested and evaluated.The main research conclusions are as follows:（1）Sb₂S₃ and its composite film were prepared conveniently,simply and successfully on a variety of substrates by a mixed solvent system of 1,2-ethylenediamine and1,2-ethanedithiol.（2）Sb₂S₃ film was prepared by electrochemical deposition and heat treatment.On ITO substrate,Sb₂S₃ film exhibits a micro-nano rod-like structure;while Sb₂S₃ film posseses a straw-like structure composed of micro-nano rods of different sizes arranged in different directions.Compared with the Sb₂S₃/ITO hydrazine electrochemical sensor,Sb₂S₃/FTO sensors obtains wider detection range and higher sensitivity.When the hydrazine concentration is 2-90μM,the sensitivity is higher to 0.04089μA/（μM·cm²）and the detection limit is lower to 0.31μM（S/N=3）.（3）An antimony sulfide/copper phthalocyanine（Sb₂S₃-CuPc）composite film was prepared by a two-step electrodeposition method.When the hydrazine concentration is2-30μM,the sensitivity of Sb₂S₃-CuPc/FTO hydrazine electrochemical sensor is0.06869μA/（μM·cm²）,and the detection limit is 0.25μM（S/N=3）,probably due to the synergistic effect of Sb₂S₃ and CuPc,the current response significantly is enhanced.（4）A composite film of antimony sulfide/tetra-β-（4-carboxyphenoxy）copper phthalocyanine（Sb₂S₃-CuTβPc）was prepared by two different methods.Sb₂S_3-CuTβPc/ITO hydrazine electrochemical sensor has been prepared by one-step electrodeposition and heat treatment,when the hydrazine concentration is 2-90μM,the sensitivity is 7.5594μA/（μM·cm²）and the detection limit is 0.099μM（S/N=3）.When the hydrazine concentration is 0.01-0.5μM,the sensitivity of Sb₂S_3-CuTβPc/Pt sensor by solution deposition is 6.97μA/（μM·cm²）and the detection limit is 0.0009μM（S/N=3）.Therefore,as a hydrazine electrochemical sensor,it is conformed that Sb₂S₃-CuTβPc composite modified electrode has the best results of sensitivity and detection limit in the present work.（5）An antimony sulfide/silver sulfide/silver（Sb₂S₃/Ag₂S/Ag）composite film was prepared by a two-step electrodeposition method.First,silver is separately plated on the ITO and FTO conductive substrates,and then Sb₂S₃ film is electrodeposited on this basis.By XRD analysis,the composite film contains not only Sb₂S₃ and Ag but also Ag₂S.The composite film of the three materials reduces the electron transport rate of the hydrazine and the electrode surface and reduces the electrochemical oxidation activity of the hydrazine.Sb₂S₃/Ag₂S/Ag/ITO is used as a hydrazine electrochemical sensor.When the hydrazine concentration is between 2-70μM,the detection limit is 1.13μM（S/N=3）,which is higher than that of a single Sb₂S₃ modified electrode.However,Sb₂S₃/Ag₂S/Ag/FTO does not have the ability to detect hydrazine.