Construction Of Bismuth-rich Bismuth Oxyhalide Materials For Photoelectrochemical Sensing

Photoelectrochemical sensor is a kind of detection method,which completely separates excitation signal（optical signal）from output signal（electrical signal）.It possesses the characteristics of high sensitivity,simple equipment,and miniaturization,which has a good application prospect in the field of food safety,environment detection and life safety.The design and development of photoelectric active materials with high photoelectric conversion efficiency is the key to enhance the analysis performance of photoelectrochemical sensor.Due to adjustable energy band structure,low cost and low-toxicity,bismuth-rich bismuth oxyhalides（Bi_aO_bX_c,X=Cl,Br,I,a/c>1）materials have attracted extensive attention in the field of photoelectrochemistry.Owing to the insufficient separation and transfer of photoinduced electron-hole pairs and the low utilization of light,Bi_aO_bX_c materials exhibit unsatisfactory photoelectric conversion efficiency.Therefore,the separation efficiency of photogenerated carriers and light harvesting ability of Bi_aO_bX_c materials are improved by strategies of constructing heterojunction and facet regulation respectively,resulting obtaining the modified materials with good photoelectrochemical performance.These Bi_aO_bX_c-based materials were utilized as photoelectric active materials to construct photoelectrochemical aptasensor to detect antibiotics and explore the detection mechanism of sensing platform.The specific research content is as follows:（1）To improve the separation efficiency of the photogenerated carriers of Bi₂₄O₃₁Cl₁₀,Bi OCl/Bi₂₄O₃₁Cl₁₀heterojunction was constructed by in-situ method.Bi OCl/Bi₂₄O₃₁Cl₁₀heterojunction was utilized as photoelectric active material to construct a high-specificity and fast-response ciprofloxacin（CIP）photoelectrochemical aptasensor.The constructed Bi OCl/Bi₂₄O₃₁Cl₁₀ heterojunction can realize the effective separation and transfer of photogenerated carriers,and the improved photoelectrochemical performance.A photoelectrochemical aptasensor was constructed based on Bi OCl/Bi₂₄O₃₁Cl₁₀ heterojunction and specific recognition element of CIP aptamer.This photoelectrochemical aptasensor had a wide detection range(5.00～1.00×10⁴ ng L^–1),a low detection limit(1.67 ng L^–1,S/N=3),high selectivity and good reproducibility.（2）Graphitic carbon nitride（g-C₃N₄）was introduced in Bi₂₄O₃₁Cl₁₀material,and the g-C₃N₄/Bi₂₄O₃₁Cl₁₀ heterojunction was prepared for constructing enrofloxacin（ENR）photoelectrochemical aptasensor.The results show that the formation of g-C₃N₄/Bi₂₄O₃₁Cl₁₀ heterojunction is beneficial for improving the separation and transfer of photogenerated carriers,reducing the recombination rate,and enhancing the response signal.A photoelectrochemical aptasensor for specifically recognizing ENR was constructed based on between g-C₃N₄/Bi₂₄O₃₁Cl₁₀ heterojunction with good photoelectrochemical performance and theπ-πconjugation between g-C₃N₄ and ENR aptamer.The photoelectrochemical aptasensor achieved a wide detection range(0.18～35.90 pg L^–1),a low detection limit(60.00 fg L^–1,S/N=3),high selectivity and good reproducibility for quantitatively detecting ENR.（3）The regulation of the exposed crystal facet of Bi₁₂O₁₇Cl₂ nanosheets was successfully realized by a solvothermal method.Bi₁₂O₁₇Cl₂ nanosheets with high exposure of（200）crystal facet exhibit narrow band gap,strong visible light absorption ability,which is conducive to the effective charge separation and transfer ability and excellent photocurrent signal.Based on the Bi₁₂O₁₇Cl₂ nanosheets with high exposure of（200）crystal facet and CIP aptamer with specific recognition ability,a highly sensitive and selective photoelectrochemical aptasensor was constructed for detecting CIP.The photoelectrochemical aptasensor had a detection range of 1.00×10^–2～1.00 ng L^–1,the detection limit of 3.33 pg L^–1,and good reproducibility.