Research On The Application Of Non-metal Quantum Dots In Alkaline Phosphatase Biosensor And Electrocatalytic Nitrogen Fixation

Quantum dots are semiconductor crystals of zero dimensional nanomaterials.Because of its small size effect,surface effect and quantum size effect,it can produce novel fluorescence performance,and expose more active sites at the same time,which makes it show unique advantages in fluorescence sensing,catalysis and other fields.The disadvantages of traditional semiconductor quantum dots are obvious,such as complicated preparation methods,expensive price,high toxicity and so on.The non-metallic quantum dots are easy to be prepared,water-soluble,functional,low toxicity and biocompatibility,which greatly expand the application of quantum dots.In view of this,the application of non-metallic quantum dots in biosensor and electrocatalytic nitrogen fixation was studied in this paper.Based on the fact that Fe³⁺can quench the fluorescence of BNQDs,the fluorescence of BNQDs can be restored and quenched under the action of PPi and ALP.We compared the fluorescence quenching rate and recovery rate of BNQDs,and reasonably designed a 300?M Fe³⁺mediated bnqds fluorescence luminescent system for ALP detection.At last,the activity of ALP can be measured in the range of 2-200 U L^-1,and the minimum detection limit is 0.8 U L^-1?S/N?3?.In addition,it can also be used to construct a new type of"INH"logic gate based on BNQDs.This study provides a more effective way for the sensitivity and selectivity of ALP.At present,the research on NRR electrocatalyst is mainly focused on metal based catalysts,while the effective activation of N2 on non-metal catalysts is still facing great challenges.We have successfully synthesized carbon quantum dots?CQDs?by one-step hydrothermal method as a new non-metallic nano catalyst with high performance and good selectivity for electrocatalytic NRR.In 0.1 M HCl electrolyte,the rate of ammonia production reached 101.33?g h^-1 mg^-1_cat.at-0.45 V vs.reversible hydrogen electrode?RHE?.The Faraday efficiency is up to 17.59%at-0.25 V vs.RHE.The results of DFT calculation further show that nitrogen adsorption is the rate determining step of NRR,and the small size of CQDs exposed rich carbon sites become the catalytic sites for nitrogen adsorption and reduction.The results show that the non-metallic quantum dots can provide more possibilities for the rational design of NRR electrocatalyst.