Fabricated Of 3D Cu-based Semiconductor Heterojunction And Performance For The High Sensitive Photoelectrochemical Sensing Of Trace-level Organic Compounds

With the improvement of living standards,people show more attention on the environment and medical treatment.To set up a rapid,accurate and sensitive method for the detection of trace-level organic compounds,such as environmental pollution and biological small molecules,become a hot spot.Thus,considering the angle of energy band theory and lattice matching theory,the 3D Cu-based semiconductor heterojunction with different functions were synthesized by simple hydrothermal and electrochemical deposition method to control the morphology and composition,including rod-like CuCo₂O₄@CoO heterojunction,dual functional flower-like Cu₂SnS₃@SnS₂ double interfacial heterojunction with tunable composition,CuCo₂S₄@CuCo₂O₄/Carbon cloth integrated electrode with abundant oxygen vacancy and A direct Z-scheme CuSnO₃@Cu₂O heterojunctions composite film.The ingenious design semiconductor heterojunction can not only broaden photoabsorption region form visible light to near-infrared light,to improve the utilization of full spectrum sunlight,but also can promote the separation of photogenerated charge carriers by the heterojunction intrinsic electric field,prolong the life of photogenic electrons,favor to improve the sensitivity and stability of PEC sensor.Furthermore,the 3D hierarchical architectures provid abundant active sites,contribute to the interaction between electrode and target.The Cu-based semiconductor heterojunction were used as working electrodes to fabricate multifunctional photoelectrochemistry?PEC?sensing platforms respectively,showing high sensitive for the trace-level diclofenac?DCF?,nitrobenzene?NB?and L-cysteine?L-Cys?,and the selectivity were controlled by adjusting of potential or forming chemical bond:1.The CuCo₂O₄@CoO composite were designed and fabricated,the rod-like morphology provid the direct electronic transmission path to promote the separation of photo-generated electrons and holes,the formation of CuCo₂O₄@CoO heterojunction could enhance the light absorption and inhibite the recombination of photo-generated carriers,which could improve the sensitivity of PEC sensor.The CuCo₂O₄@CoO was used as photoanode for the detection of nonsteroidal antiinflammatory drugs?NSAIDs?diclofenac?DCF?,which shows electrochemical activity.The CuCo₂O₄@CoO/FTO shows selective photocurrent response to DCF among the other NSAIDs by controlling the bias potential to regulate the redox ability of electrode,and the DCF can be oxidized by photogenerated hole to produce“signal-on”photocurrent.The photocurrent was linearly proportional to the concentration of DCF ranging from 1 nmol L^-1 to 500?mol L^-1,and the detection limit?S/N=3?was 6.5 nmol L^-1.The CuCo₂O₄@CoO/FTO PEC sensor was used to analyze the DCF in tap water and waste water with satisfactory results.2.Novel designed and fabricated 3D flower-like Cu₂SnS₃@SnS₂ double interfacial heterojunction,the formation of sandwich-like Cu₂SnS₃-SnS₂-Cu₂SnS₃ double interfacial p-n heterojunction can promote the separation of photogenerated electrons and holes by the intrinsic electric field to improve the PEC performance.The 3D architectures favor to optical absorption by multi-light scattering/reflection,to enhance the light absorption.It also possesses the highest surface areas and more active sites to improve the sensitivity of PEC sensor.Furthermore,the composition ratio of p-type Cu₂SnS₃/n-type SnS₂semiconductors can be manipulated by changing the electrodeposition time,the Cu₂SnS₃@SnS₂ can not only used as photoanode,but also used as photocathode to sensoring two different analytes.While the Cu₂SnS₃@SnS₂/FTO was used as photoanode,it can selective detect L-Cys by the formation of Cu-S bond.The photocurrent was linearly proportional to the concentration of L-Cys ranging from 10 nmol L^-1 to 100?mol L^-1,and the detection limit?S/N=3?was 8.5 nmol L^-1.While the Cu₂SnS₃@SnS₂/FTO was used as photocathode,it can ultra-sensitive detect trace nitrobenzene?NB?.The photocurrent was linearly proportional to the concentration of NB ranging from 100 pmol L^-1 to 300?mol L^-1,and the detection limit?S/N=3?was 68 pmol L^-1.The compound amino acid injections,urine and serum were used as real samples to evaluate the practical application ability,result is satisfactory.3.The CuCo₂S₄@CuCo₂O₄/CC integrated electrode were fabricated by in-situ growth method,the 3D CuCo₂S₄@CuCo₂O₄ nanoneedle array uniformly and closely grow on the surface of conductive substrate?carbon cloth?.The 3D nanoneedle array architectures favor to optical absorption by multi-light scattering/reflection,to improve the utilization of sunlight,it can also expose active site on the edge to improve the sensitivity of PEC sensor.The in-situ heterojunction and integrated electrode structure could reduce interface electron transfer resistance to promote the separation of photogenerated carriers,improve the stability of PEC sensor.The in-situ formation of CuCo₂S₄@CuCo₂O₄ heterojunction can not only broaden photoabsorption region form visible light to near-infrared light,but also can promote the separation of photogenerated electrons and holes.The carbon cloth with excellent conductivity could further promote interfacial photo-generated electrons transfer,effective inhibite the recombination of photo-generated carriers to improve the PEC performance of sensor.Furthermore,abundant oxygen vacancy produced during the in-situ transformation process,which could improve the catalytic ability of the electrode to accelerate the redox reaction of target,favor to improve the sensitivity of PEC sensor.The CuCo₂S₄@CuCo₂O₄/CC was used as photoanode and the PEC analysis method of NB was established.The photocurrent was linearly proportional to the concentration of L-Cys ranging from 5nmol L^-1to 500?mol L^-1,and the detection limit?S/N=3?was 4.7 nmol L^-1.The L-Cys can be selective detected by the CuCo₂S₄@CuCo₂O₄/CC electrod via the formation of Cu-S bond,it serves as electron donor and oxidized by photogenerated hole to produce“signal-on”photocurrent,to realize the ultra-sensitive and selective detection of L-Cys.The CuCo₂S₄@CuCo₂O₄/CC PEC sensor was used to analyze the L-Cys in urine,serum and compound amino acid injections with satisfactory results.4.A direct Z-scheme CuSnO₃@Cu₂O heterojunctions film were reasonably designed and fabricated,the 3D architectures favor the utilization of visble light,Z-scheme system and CuSnO₃@Cu₂O heterojunctions can not only improve the separation efficiency of photogenerated charge carriers,but also maintain high redox ability of photogenerated electrons and holes to make the CuSnO₃@Cu₂O with high efficiency PEC catalytic performance.The CuSnO₃@Cu₂O/FTO was used as the photocathode for the detection of nitrobenzene?NB?,the photocurrent was linearly proportional to the concentration of NB ranging from 0.5 nmol L^-1 to 100?mol L^-1,and the detection limit?S/N=3?was 0.43 nmol L^-1,the CuSnO₃@Cu₂O/FTO PEC showed excellent anti-interference ability,good reproducibility and high stability.Furthermore,CuSnO₃@Cu₂O was used as catalyst,showing high catalytic activity for the preparation of aniline by PEC reduction of nitrobenzene.The reduction product were analyzed by UV-vis spectra and HPLC,the PEC catalytic reduction efficiency of NB can reach85.70%and the corresponding yield of AN was about 62%within irradiation for 2.5 h.The results indicated the CuSnO₃@Cu₂O/FTO PEC platform showing dual function for the ultrasensitive sensing and high effective degradation of NB,which can promote the development of environment detection and pollutant treatment technology.