| Heavy metal ions,such as lead,copper,cadmium and manganese,are toxic and harmful,which bring about serious damage to the body’s immune system,central nervous system and reproductive system even if the present of trace amounts of them.It is usually difficult to degrade,resulting in the enrichment of ecosystems,causing heavy metal pollution,severely damaging the ecological environment,and threatening human health activities.How to effectively monitor heavy metal pollution is particularly important.Exploring effective detection methods is of great significance for preventing heavy metal pollution.Nowadays,electrochemical detection method has been developed as an important detection method.It is one of the best choices for online monitoring since it has the advantages of high sensitivity,low detection limit,simple operation and portable equipment.However,in the electrochemical detection method,the selection of the surface modification material of the electrode is crucial for the improvement of the detection effect.TiO2 as an important semiconductor material,has the advantages of good stability,safety,non-toxicity and low cos.It has been widely studied by experts and scholars.At the same time,the two-dimensional ultra-thin nanosheet structure has the advantages of large specific surface area,multiple reactive sites and high stability.However,there are few reports on the detection of heavy metal ions by utilized two-dimensional ultrathin TiO2 nanosheets(2D TiO2 NSs).This article will use two-dimensional ultrathin TiO2 and non-metal doped nanosheet modified glassy carbon electrode for the detection of heavy metals Pb(Ⅱ)in water,the experimental mainly contents the following steps.Firstly,two-dimensional ultrathin TiO2 nanosheets were prepared by a one-step hydrothermal method.The glassy carbon electrodes were used to prepare electrochemical sensors for the detection of lead ions.The experiment explored the conditions that affect the signal response:support buffer,deposition potential,deposition time,and buffer pH optimization.The results show that the best response is obtained when the support buffer is NaAc-HAc solution,deposition potential of-1 V and a solution pH of 5.0,Considering the efficiency problem,the deposition time was selected as 150 s.At this point,the detection range of Pb(Ⅱ)is 0.1 μM～1.5μM,showing a good linear relationship.Secondly,hydrothermally doping of 2D TiO2 NSs with non-metals(F,S,I).Different doping concentrations of 2D TiO2 NSs were prepared and modified glassy carbon electrodes were used for the detection of Pb(II).Under the optimal detection conditions,Modified materials exhibited a better current signal response than pure TiO2 and the linearity was good in the range of 0.2 μM～1.4μM.F-doped TiO2 NSs exhibited the highest electrochemical sensitivity and the best detection limit when the doping concentration was 10%.Compared with pure TiO2 NSs,the sensitivity increased by 102%and the detection limit decreased by 36.4%to 7 nM,which was far lower than the World Health Organization requirement of 90 nM for lead in drinking water.Finally,the reasons for improving the doping performance of F elements were investigated by using the first-principles calculations combined with electrochemical test.The experimental data is in good agreement with the calculation results,indicating that the doping contributes to electron transfer at the electrode surface.The theoretical calculation results show that the adsorption energy of Pb(Ⅱ)on the TiO2(101)surface increases and the capacity of the immobilized heavy metal Pb(Ⅱ)increases after F-doped TiO2,thus the response signal is better.At the same time,the effects of F-doped TiO2 NSs on the reproducibility,stability and anti-interference of the modified electrode were studied.The results show that F-doped TiO2 NSs have good reproducibility,stability and anti-interference.It is expected to be applied in real life. |
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