| Recently, heterostructures consisting of two or more components have attracted great attention due to their superior optoelectronic properties compared to corresponding individual material. Especially, the unique hetero-interface can promote the separation and transfer of charge carriers, which make them a potential candidate in photocatalysis and biosensor fields. In this work, we fabricated g-C3N4/Bi2S3 and Ag@C heterostructures, and systematically studied their applications on photocatalysis and biosensor. The details are summerized as follows:(1) Firstly, g-C3N4/Bi2S3 heterostructure was successfully synthesized through a microwave-assisted method. g-C3N4 powder was prepared by thermal polycondensation of melamine. Then the in situ crystal growth reaction of Bi2S3 occurred on the surface of g-C3N4 was achieved by microwave treatment. The as-prepared g-C3N4/Bi2S3 composites exhibited enhanced photocatalytic performance for degrading methyl orange(MO) under visible-light irradiation and g-C3N4/Bi2S3-24 composite showed the best photocatalytic ability, whose MO removal rate reaches to 99.5% after 3 h of visible light irradiation. Based on the experimental results, a photocatalytic enhancement mechanism of was proposed for g-C3N4/Bi2S3 heterostructure: the hybridization of Bi2S3 with g-C3N4 can increase visible-light absorption, and the interface of g-C3N4/Bi2S3 heterostructure is beneficial to facilitate the separation of photo-generated electron-hole pairs, thereby improving the photocatalytic property of g-C3N4/Bi2S3 composites.(2) Secondly: one-step hydrothermal method was employed in synthesizing Ag@C core-shell structure. The as-prepared products were characterized by XRD, TEM, FTIR, which confirmed the well-crystallized nano-Ag-core and colloid carbon shell rich of functional group such as –OH and –COOH. Then the as-prepared Ag@C was employed for the immobilizing of glucose oxidase to construct the GOD-Ag@C/Nafion/GCE electrochemistry biosensor. The GOD-Ag@C/Nafion/GCE biosensor exhibited good electrocatalytic property for the detection of glucose with enhanced signal. Based on the results, the biosensor was applied in the determination of glucose in real serum sample, and the results revealed that the proposed biosensor is reliable and effective. The redox peak current was linearly dependent on the glucose concentration in the range of 0.05~2.5 m M with a correlation coefficient of 0.995, the detection limit is 0.02 m M, and the sensitivity is 24.65 mAm M-1cm-2 under optimum experiment conditions. In addition, the as-prepared biosensor possesses stability and reproducibility. The excellent properties of the GOD-Ag@C/Nafion/GCE biosensor was mainly attributed to the synergistic effect of Ag nanoparticle and the colloid carbon shell: the Ag core can facilitate the electron transfer, and the colloid carbon shell can improve the biocompatibility, hydrophilicity and stability of the Ag core, and improve the property for the immobilizing biomacromolecules.In this work, g-C3N4/Bi2S3 and Ag@C heterostructures were successfully synthesized and applied as visible-light-driven photocatalyst and biosensor. It was found that the heterostructure can realized the efficient separation and transfer of charge carriers, and thus improve the photocatalytic property and biosensing property. |
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