Highly Sensitive Detection Of Microcystin-LR Under Visible Light Using A Self-powered Photoelectrochemical Aptasensor Based On A CoO/Au/g-C₃N₄ Z-scheme Heterojunction

As a new analysis method based on photoelectric conversion,photoelectrochemical（PEC）detection technology has attracted a lot of researchers’s attention in recent years.Under the visible light,the photosensitive materials would absorb photons and cause electron excitation and charge transfer,creating the photo-generated electron-hole pairs at the interfaces.Upon the target analytes anchored on the surface of modified electrode,a redox reaction between it and photo-generated electron-hole pairs would affect the charge transfer,resulting the corresponding electrical signal to change.Because the complete separation between the excitation light source and the detection signal,the PEC detection technology has high sensitivity and extremely fast response speed.In this paper,a new type of PEC aptasensor is constructed based on the Z-scheme heterojunction of CoO/Au/g-C₃N₄ and a nucleic acid aptamer,realizing a highly selective and sensitive quantitative detection of microcystin-LR（MC-LR）.The main research work is as follows:The CoO/Au/g-C₃N₄ composites was cleverly constructed by hydrothermal method and photoreduction method.As an excellent electronic conductor with plasmon resonance effect（SPR）,Au nanoparticle（NPs）can enhance the capability of light absorption of the photosensitive composite.Besides,Au NPs can also act as an electronic bridge between CoO and g-C₃N₄,change the original electron transfer path and form a Z-scheme heterojunction,which makes the photogenerated electrons and holes are gathered in the high potential energy band,improving the REDOX capacity of them.And the combination with the specific nucleic acid aptamer probe makes the CoO/Au/g-C₃N₄ composites highly selective to the target analystes.Thanks to the high photoelectric performance of the Z-scheme heterojunction CoO/Au/g-C₃N₄ composites,the sensitivity of the PEC aptasensor is greatly improved and the signal-to-noise ratio is also reduced.In conclusion,the proposed PEC aptasensor in this paper has the advantages of high stability,long service life,strong anti-interference ability,wide detection range and low detection limit,which can achieve the highly selective and sensitive quantitative detection of MC-LR,and has a good application value and prospects.