The PEC process,involving the generation of electron-hole（e⁻-h⁺）pairs under light irradiation,and energy transfer between the electron donor/acceptor and the optoelectronically active material^[32]。 Among them,the charge separation and transport of optoelectronically active materials determine the photoelectric conversion efficiency.Organic ligands play a key role in the optoelectronic properties of MOFs^[33]。 The photoelectric effect shows that when a photon with a certain energy or a photon with an energy exceeding the bandgap energy（E_g）of MOFs is injected into MOFs,the electron in the Valence band(VB)absorbs the photon energy and then jumps to the Conduction band(CB),leaving a hole in the Valence band and an electron in the Conduction band,forming an electron-hole pair.By selecting appropriate organic ligands and metal nodes to construct an electron donor-acceptor structure,the band gap of MOFs can be effectively reduced,thus achieving high photoelectron conduction efficiency.Photogenerated electrons may combine with holes to release energy in the form of thermal dissipation,and may also form anodic photocurrent or cathodic photocurrent under a certain bias(Fig.1).Under the action of bias voltage,when the photogenerated electrons are transferred to the external circuit to generate holes on the electrode surface,the holes will be captured by the electron donor(ED)in the electrolyte solution for oxidation reaction,and the electrode circuit will be completed to form the anode photocurrent,as shown in Figure 1A^[34]; When the photogenerated electrons are transferred to the electrode/electrolyte solution interface,the photogenerated electrons undergo a reduction reaction with the electron acceptor(EA)in the electrolyte solution,and the electrons input to the electrode surface by the external circuit enter the valence band of the MOFs and are captured by holes,forming a cathodic photocurrent,as shown in Figure 1b。

Suppression of electron-hole recombination is essential to boost the photocurrent signal.Generally speaking,electron and hole recombination in MOFs semiconductor materials can be carried out through different mechanisms such as direct recombination,defect-assisted recombination,and surface recombination.Among them,direct recombination is the main recombination mechanism,in which electrons and holes meet directly and energy is released during recombination.the rate of this recombination mechanism is related to the density of electrons and holes.defect-assisted recombination means that when an electron or hole encounters a defect,the electron-hole pair stays near the defect,resulting in recombination under the energy level interaction of other ions or impurities.surface recombination is that electron-hole pairs migrate from the bulk phase in the semiconductor material to the surface of the photoactive material for reintegration,and react electrochemically with the electroactive material,and the redox reaction products stay on the photoactive surface due to the adsorption of the electroactive material^[35]。 in addition to the semiconductor type,the redox potential of the VB/CB site and electrolyte morphology of MOFs-based photoelectrodes can also affect the electron-hole pair migration and reaction rate.From a thermodynamic point of view,the necessity of this redox reaction lies In the fact that the potential of the oxidant must be greater than the positive potential of CB and the potential of the reductant must be greater than the negative potential of VB^[36]。 According to this rule,the construction strategy of Photoelectrochemical sensors can be changed by adjusting MOFs-based photoelectrodes。

Photoelectrochemical processes involve not only energy conversion,but also charge release,electron transfer and interfacial reaction processes,which are closely related to photoelectric conversion efficiency and Photoelectrochemical reaction kinetics.the preparation,modification,and composition of MOFs-based materials play a key role in The effective design of Photoelectrochemical sensing interfaces。

MOFs-based photoelectroactive materials have become an important part of nanoporous materials in recent years due to their unique structural and functional properties.According to the current literature reports,the main synthesis methods are solvothermal/hydrothermal method and solution method,and other synthesis methods such as electrochemical synthesis,mechanochemical synthesis and ultrasonic synthesis have gradually attracted the attention of researchers due to their different advantages,as shown in Table 1^{[37⇓⇓⇓⇓~42][20,31][43⇓⇓~46][47⇓⇓⇓⇓~52][53⇓⇓~56]}。 Solvothermal synthesis is the most widely used in Photoelectrochemical sensing detection,for example,Yang et al.Used solvothermal method to synthesize NH₂-MIL-125(Ti)for the construction of molecularly imprinted Photoelectrochemical sensing platform^[41]。 Wang et al.Prepared Zr-MOFs(UiO-66 as a model)by solvothermal method at 120°C to construct a Photoelectrochemical biosensor for detecting kinase activity^[42]。 the solution method is to prepare MOFs-based optoelectronic active materials by dissolving metal ions and organic ligands in a solvent and controlling the temperature and pH value of the solution.Gao et al.Prepared Eu-MOF in ethanol-water containing 1,3,5-benzenetricarboxylic acid at room temperature and applied it to a class of self-supplied electro-optic electrochemical aptasensor^[20]。 Yang et al.Synthesized nanopolyhedrons based on ZIF-8 in anhydrous methanol solvent,showing superior Photoelectrochemical activity^[31]。 Electrochemical synthesis is a method to form MOFs by ionizing metal ions from the anode and then combining with organic ligands in the solvent.Yang fabricated TiO₂@ZIF-8 Photoelectrochemical sensing platform for the detection of lactic acid using cascade electrospinning and hot pressing technology^[45]。 Asghar et al.Synthesized a new type of amine-functionalized Mn-diaminophthalate MOFs by electrochemical synthesis,and compared the CO₂and H₂absorption of Mn-phthalate MOFs synthesized by traditional solvothermal method^[46]。 The results show that the Mn-diaminophthalate MOFs prepared by the electrochemical synthesis method exhibit high CO₂adsorption capacity(92.4 wt%at 15 ATM and 273 K)and H₂adsorption capacity(12.3 wt%at 80 ATM and 77 K).The mechanochemical method is mainly to prepare MOFs by mixing metal salts and ligand reactants in a certain proportion,and reacting them without or with a small amount of solvent through mechanical force or grinding.Zhang et al.Used for the rapid synthesis of nickel-based metal-organic frameworks(Ni-MOFs),and the synthesis reaction of Ni-MOFs can be completed within 1 min without any solvent,additive,or pre-preparation^[51]。 Zhou et al.Synthesized BiVO₄/g-C₃N₄heterojunction and TiO₂@NH₂-MIL-125(Ti)by grinding,which greatly improved the photoelectric activity^[52]。 in the ultrasonic synthesis method,bubbles are continuously generated in the liquid under the action of ultrasonic waves,and then the collapse of the bubbles increases the temperature of the local solvent,and with the change of pressure,the reaction temperature changes,and finally MOFs are Synthesized in a very short time.Wei et al.synthesized IBABR-Au@Zn-MOF by ultrasonic method,and successfully constructed a Photoelectrochemical sensing platform for the detection of squamous cell carcinoma antigen^[53]。 Son et al.Synthesized MOF-5 by ultrasonic method,and You Jiayong et al.Synthesized metal-organic framework HKUST-1 by ultrasonic treatment with different inorganic copper salts and organic ligand trimesic acid^[55][56]。 These methods are expected to be further developed and promoted in the synthesis and application of MOFs-based optoelectronic active materials because of their advantages such as short synthesis time,low reaction temperature,controllable reaction rate,uniform nucleation,and high porous yield(Table 1)。

Carbon-based compounds,as excellent optical sensing materials(such as carbon nanotubes and graphene),have excellent light absorption and photoelectric conversion properties,which can be used to prepare efficient Photoelectrochemical sensors.Zhang Xue constructed a MOFs-based Photoelectrochemical sensing interface based on the modification of MIL-68(In)-NH₂/MWCNT/CdS multi-walled carbon nanotubes,which was used to detect tetracycline in water.The synergistic effect of MWCNT(multi-walled carbon nanotube)and MIL-68(In)-NH₂/CdS heterojunction accelerated the electron migration and improved the photoelectric conversion efficiency,showing high selectivity,reproducibility and stability^[61]。 Travlou et al.Reported a Photoelectrochemical sensing interface of copper-based MOFs modified with graphene oxide or aminated graphene oxide for low concentration ammonia sensing detection^[62]。 the results show that the high adsorption capacity and superior conductivity of MOFs and graphene can greatly increase the ammonia adsorption efficiency,thereby improving the sensitivity and response speed of the sensor.Yin et al.Reported a Photoelectrochemical sensing interface constructed by polypyrrole nanofiber-coated reduced graphene oxide-modified Cu-BTC nanoparticles,which achieved highly sensitive detection of ammonia^[63]。 To sum up,based on the high conductivity and high surface area of graphene and carbon nanotubes,this kind of MOFs-based Photoelectrochemical sensing interface has the advantages of dispersed Photoelectrochemical catalytic sites,fast electron transport and stable network structure。

Organic polymers have become one of the important strategies for the preparation of Photoelectrochemical biosensing interfaces because of their outstanding characteristics such as high conductivity,high visible light absorption,high carrier capacity,and good environmental compatibility in the doped state.Bhardwaj et al.Reported that ammonium persulfate was used as an oxidant to polymerize the aniline component into polyaniline to improve the semiconductor properties of the sensor material,and to bridge the Cu-MOF and graphene in the composite material.A three-phase composite material composed of Cu-MOF@SiO₂,monolayer graphene and aniline was constructed for ammonia Photoelectrochemical sensing,which improved the sensitivity of the sensor to ammonia and realized the highly sensitive detection of ammonia^[64]。 Shang et al.Constructed a novel polypyrrole-modified nanohybrid Cu₉S₈/PPy/ZIF-67 bimodular MOFs-based Photoelectrochemical sensing interface with high selectivity for hydrogen sulfide detection^[65]。 ZIF-67 has ideal energy band and whole oxidase mimicking activity,and the Photoelectrochemical signal can be greatly improved by coupling the Cu₉S₈with a well-matched energy band structure nanomaterial,While PPy can provide fast electron transport,wide photoelectric response range and local incorporation of metal precursors,which can construct metal nanostructures sandwiched between copper sulfide（Cu₉S₈）core and MOFs(ZIF-67)shell.The construction idea of the nanohybrid bimodular MOFs-based Photoelectrochemical sensing interface also provides a favorable reference for the preparation of bifunctional nanohybrids.Yang et al.Prepared a novel Photoelectrochemical composite（NH₂-MIL-125(Ti)-TiO₂）based on MOF and TiO₂.Then the oxytetracycline is used as a template molecule,the o-phenylenediamine is used as a polymerization monomer,and the poly-o-phenylenediamine modified MOFs-based Photoelectrochemical sensing interface with a molecular imprinting recognition function is formed by electropolymerization on the surface of a NH₂-MIL-125(Ti)-TiO₂/ITO electrode,so that the molecularly imprinted Photoelectrochemical sensor is developed,and the ultra-sensitive detection of oxytetracycline is realized^[41]。 Organic polymer-modified MOFs-based Photoelectrochemical sensing interface has the advantages of processable soft system and controllable pore environment.of course,due to the incompatibility of the two parent materials of polymer and MOFs,there are still some challenges in the precise control of the proportion and distribution of the two in the composite。

Noble metal nanoparticles have excellent conductivity,which is beneficial to improve the Photoelectrochemical sensing reaction.Noble metal nanoparticle-integrated MOFs-based materials can effectively improve the analytical characteristics of Photoelectrochemical biosensing interfaces.Qin et al.Coordinated imidazolium ionic liquid as an organic ligand with Zn²⁺to prepare ladder-shaped metal-organic framework(Zn-MOF)nanosheets^[28]。 Then,gold nanoparticles(AuNPs)were integrated onto the surface of Zn-MOF nanosheets by in situ reduction of chloroauric acid to construct the Photoelectrochemical sensing interface of MOFs for AFP immunosensing.Gong Chengju developed a MOFs Photoelectrochemical sensing interface based on Ag NPs/MIL-100(Fe)@CdS noble metal nanoparticle modification,which modified Ag nanoparticles on the surface of MOFs-based Photoelectrochemical sensing electrode,accelerated electron transfer,slowed down the recombination of electron-hole pairs,enhanced the Photoelectrochemical sensing performance,and successfully applied to the highly sensitive detection of cysteine^[16]。 Zhang et al.Established a Photoelectrochemical sensor for ochratoxin A(OTA)detection based on the Au NPs/CdS/UIO-66-NH₂heterostructure as a photoelectroactive material using the CRISPR/Cas12a system(Fig.2 )^[66]。 The ternary heterostructure of Au NPs/CdS/UiO-66-NH₂suppresses the recombination of electron-hole pairs and improves the photocurrent conversion efficiency.Methylene blue-labeled ssDNA was immobilized on the electrode surface as a sensitizer,and the target OTA specifically triggered the release of the strand and activated the CRISPR/Cas12a trans-cleavage activity.The sensor had a wide detection range(50~100 ng/mL)and a detection limit of 38 fg/mL.Studies have shown that MOFs are ideal candidates for stabilizing noble metal nanoparticles because of their good pore-controlled environment.However,the position of noble metal nanoparticles relative to MOFs particles,whether inside or on the outer surface of MOFs,has not yet been determined in the literature 。

MOFs-based inorganic oxide composite sensing materials are compounded with MOFs by selecting semiconductors with different band gaps and matching conduction band energy levels.Yang et al.Developed an inorganic oxide-modified MOFs-based Photoelectrochemical sensing interface for NPC-ZnO nanopolyhedra via direct carbonization of ZIF-8,using alkaline phosphatase(ALP)as a model^[31]。 Kong et al.Prepared Cu(OH)₂nanowire arrays grown on copper mesh(CM)by in situ oxidation reaction,and used them as precursors to successfully fabricate the Photoelectrochemical sensing interface of MOFs modified by Cu₂O@Cu-MOF/CM inorganic oxides.The prepared inorganic oxide 3D nanoarray material has a large specific surface area and excellent stability,which is conducive to improving the performance of PEC^[30]。 Yang used cascade electrospinning and hot pressing technology to efficiently prepare MOFs-based Photoelectrochemical sensing interface modified by TiO₂@ZIF-8 inorganic oxides,which realized the highly sensitive and selective detection of lactic acid^[45]。 the close interfacial contact between inorganic oxides and MOFs can generate more surface defects,thereby enhancing the interaction between them and improving the electron transfer efficiency after photoexcitation.It has been reported that compounding appropriate oxides with MOFs to form heterostructures is a potentially effective modification,and how to control the heterostructure of MOFs for central metal ion exchange still needs further study。

As a photoelectric active material,quantum dots have good photoelectric effect and stability.One photon can excite multiple electron-hole pairs to form multiple photoelectrons,which can improve the photocurrent signal and reduce the interference of background signals.Yan et al.Synthesized a MOFs-based Photoelectrochemical sensing interface modified by ZnIn₂S₄@NH₂-MIL-125(Ti)quantum dots through a one-step solvothermal method,and achieved efficient Photoelectrochemical detection of 17β-estradiol^[25]。 Wei et al.Used a solvothermal method to synthesize a novel metal-organic framework nanocrystal(Zn-MOF)with carboxyl-functionalized ionic liquid as the monomer and Zn²⁺as the central metal ion^[17]。 Zn-MOF was used as a template to integrate MoS₂nanosheets through the reaction of ammonium molybdate and thiourea,followed by carbonization at 600°C to obtain the Photoelectrochemical sensing interface of MOFs constructed by modification of ZnS/C/MoS₂quantum dots.The carbonization of Zn-MOF and the formation of ZnS QDs and MoS₂QDs can improve the photocurrent response under visible light,thus enabling the Photoelectrochemical highly sensitive determination of carcinoembryonic antigen.It has been shown that the encapsulation of quantum dots within MOFs can improve their stability and tune the electron-hole recombination rate.The precise control of the spatial arrangement of quantum dots by optimizing the pore environment of MOFs will become the development direction of the interface design 。

Small molecular compounds are an integral part of life.Semiconductors derived from MOFs materials have excellent photoelectric conversion efficiency,and have been successfully used for the analysis and detection of antibiotics,diethylstilbestrol,estradiol,H₂O₂,cysteine and other small molecular compounds,and a series of Photoelectrochemical sensors with high stability and sensitivity have been successfully developed^{[20⇓~22][26][25][67][16]}。

the abuse of antibiotics leads to environmental pollution and ecological hazards,so the accurate detection of trace antibiotics becomes necessary and urgent.Gao et al.Constructed a Photoelectrochemical biosensing interface for the detection of ampicillin(AMP)based on the complex of CdS nanoparticles and europium metal-organic framework(Eu-MOF),and immobilized an AMP-conjugated aptamer as a recognition element on the CdS/Eu-MOF modified electrode,which realized the specific photocurrent response to AMP^[20]。 Dong et al.Developed a MOFs-based cathode Photoelectrochemical sensing interface for ultrasensitive detection of kanamycin sulfate(KAM)based on g-C₃N₄-coupled zirconium-based porphyrin metal-organic framework(PCN-222)(Fig.3),and the synergistic effect between g-C₃N₄and PCN-222 effectively reduced carrier recombination and improved photoelectric conversion efficiency,and the study showed that the initial photocurrent of PCN-222@g-C₃N₄was 2.78 and 49 times higher than that of pure PCN-222 and g-C₃N₄,respectively^[21]。 Zhang et al.Reported a MIL-68(In)-NH₂/MWCNT/CdS complex system and used it for the detection of tetracycline.In the detection process,the appropriate ligand of tetracycline(Tc)will specifically capture Tc molecules in solution,and the photocurrent signal will be enhanced by the transient reaction between the captured Tc molecules and the photogenerated holes,which shows good selectivity in the detection of antibiotic residues in the environment^[22]。 In order to meet the urgent need for the detection of diethylstilbestrol(DES),Wu et al.Used Au/UIO-66(NH₂)/CdS composite as a photoelectric active material to prepare a competitive Photoelectrochemical immunosensor for the detection of diethylstilbestrol(DES).Under the optimal conditions,the linear range of DES was 0.1 pg/mL~20 ng/mL,and the detection limit was 0.06 pg/mL^[26]。

Yan et al.Developed a competitive PEC immunosensor for the detection of 17β-estradiol with a detection range of 0.0005–20 ng/mL using ZnIn₂S₄@NH₂-MIL-125(Ti)complex as the matrix and polydopamine nanospheres loaded with Mn:ZnCdS quantum dots as the antibody label^[25]。 The novel semiconductor@MOFs core-shell heterostructure is a new type of Photoelectrochemical sensing interface with molecular selectivity.Zhan et al.Prepared a core-shell heterostructure of ZnO@ZIF-8 using a self-templating strategy and successfully used it for the detection and analysis of H₂O₂.This synthesis strategy opens up a new way for the preparation of MOFs-related core-shell heterostructures Photoelectrochemical sensing interface^[67]。 cysteine has a positive correlation with diabetes,liver injury and other diseases.Gong Chengju synthesized Ag NPs/MIL-100(Fe)@CdS nanocomposite by solvothermal method,and established a bio-photoelectrochemical sensing interface for Cysteine detection on the Ag NPs modified working electrode.the sensor can be used for the actual detection of human serum samples and urine^[16]。 As the carrier of small molecule signal probe,the application of MOFs-based materials in the field of small molecule detection is still relatively single,and the detection methods also have some limitations.the follow-up research focuses on optimizing the framework design and improving the effective loading of MOFs-based materials。

Photoelectrochemical immunosensor is a biosensor based on the coupling of immunochemical reaction and Photoelectrochemical sensing interface.Its applications have been involved In a wide range of fields such as clinical medicine and biological monitoring.in the Photoelectrochemical immunosensing interface,when the antigen/antibody inducer is deposited on the electrode surface as a non-electroactive molecule,the photocurrent will change,thus realizing the detection of the target.for example,Zhang et al.used DNA-mediated NMOFs composite as a photoelectric active material to prepare an enzyme-free Photoelectrochemical immunosensing interface For detecting prostate specific antigen(PSA)(Fig.4),and stably loaded ss-DNA-labeled antibody(Ab-DNA)on NMOF.the Ab-DNA-functionalized NMOF was obtained,and then the carboxyl-terminal polyamidoamine(PAMAM)dendrimer was functionalized to load the antibody more effectively.Under the optimal conditions,the detection range of PSA was 1.0~10.0 ng/mL,and the detection limit was 0.2 pg/mL^[18]。 Wei et al.Deposited IBABR-Au@Zn-MOF nanocomposite on a glassy carbon electrode,and then immobilized anti-squamous cell carcinoma antigen(Anti-SCCA).When SCCA was combined with Anti-SCCA,the photocurrent decreased due to the blocking effect of SCCA on electron and mass transfer,thus achieving highly sensitive detection of SCCA^[53]。 Wang et al.Used Bi₂O₃/B-TiO₂/Ru@UiO-66 nanocomposite as photoactive material to establish a novel Photoelectrochemical immunosensor based on signal amplification strategy for highly sensitive detection of m⁶A,with a detection range of 0.05–30 nmol/L and a detection limit of 0.0167 nmol/L^[68]。 Zhou et al.Fabricated a highly sensitive Photoelectrochemical immunosensing interface based on BiVO₄/g-C₃N₄heterojunction and TiO₂@NH₂-MIL-125(Ti)for the determination of m¹A,which can be used as an alternative detection platform for m¹A analysis^[52]。

Human epididymis protein 4(HE4)is a serum biomarker of ovarian cancer,which has advantages in early diagnosis of ovarian cancer.Chen et al.Successfully prepared a novel"signal-type"Photoelectrochemical immunosensing interface based on nPCN-224 and Nb coupling,and used it for the detection of HE4.the immunosensor has a detection range of 1.00~10.0 ng/mL and a detection limit of 0.560 pg/mL,which opens up a new way for clinical diagnosis and clinical efficacy evaluation in the future^[69]。 Zhang et al.Successfully assembled a label-free Photoelectrochemical sensing platform based on 00005 for the detection of carcinoembryonic antigen.Under the optimal conditions,the Photoelectrochemical biosensor had a wide detection range of 0.00005~500 ng/mL and a detection limit of 2.28 fg/mL^[19]。 MOFs-based materials used in Photoelectrochemical immunoassay also have the problem of poor water stability,which may be improved by introducing hydrophobic groups or preparing high-valence metal high-coordination MOFs。

Enzymatic biosensing is of universal and important significance In bioanalytical detection.in the Photoelectrochemical enzyme biosensor,the Photoelectrochemical enzyme system converts the biocatalytic signal into an electrical signal through the interaction between the semiconductor substance and the biocatalytic reactant after illumination.Yang et al.Used ZIF-8 as a precursor to form nitrogen-doped porous carbon-zinc oxide(NPC-ZnO)nanopolyhedrons by high temperature carbonization,and modified the NPC-ZnO nanopolyhedrons on the electrode surface to construct a MOFs-based Photoelectrochemical biosensing interface(Fig.5).the obtained NPC-ZnO nanopolyhedrons effectively promote the separation of electron-hole pairs,thereby realizing the efficient Photoelectrochemical detection of alkaline phosphatase,and the sensor has a detection range of 2 to 1500 U/L and a detection limit of 1.7 U/L^[31]。 Wang et al.Developed a Photoelectrochemical biosensor for ultrasensitive protein kinase A activity detection based on zirconium cluster-based MOFs(UIO-66 as a model)as the carrier of photoelectroactive materials with phosphate groups^[42]。 To sum up,MOFs-based materials are suitable for enzyme analysis and detection,on the one hand,they can create a stable microenvironment for different enzyme molecules,on the other hand,they have a large number of active sites and mimic the properties of natural enzymes。

Protein is the material basis of life,the basic organic matter of cells,and the main undertaker of life activities.Therefore,the analysis and research of protein is of great significance in the field of human health,and the Photoelectrochemical sensing interface related to protein has attracted much attention.Protein Photoelectrochemical sensor is based on the detection of protein by the change of photocurrent caused by the steric hindrance effect after the binding of a receptor of a related protein to a specific substance on the electrode surface.Zhou et al.Developed a CdS quantum dot sensitized titanium-based metal-organic framework as a high-performance Photoelectrochemical cathode material,and constructed a simple and effective Photoelectrochemical immunoassay platform for the detection of alpha-fetoprotein based on the Ag⁺exchange strategy^[70]。 Zhang et al.Developed a Photoelectrochemical sensing interface for label-free detection ofα-casein based on zirconium-based porphyrin MOFs(PCN-222),which has a high detection sensitivity with a detection limit of 0.13μg/mL due to the steric hindrance effect formed by the coordination between the phosphate group in PCN-222 and the inorganic Zr-O cluster^[29]。 Vascular endothelial growth factor is a functional glycoprotein with high biological activity.Kong et al.Successfully prepared Cu₂O@Cu-MOF/CM nanoribbon arrays by in situ growth method,and combined with rolling circle amplification and enzyme-catalyzed precipitation technology to construct a Photoelectrochemical sensing interface for vascular endothelial growth factor 165 analysis,with a detection range of 10.0~1.0×10⁸pmol/L and a detection limit of 2.3 pmol/L^[30]。 the study shows that MOFs-based Photoelectrochemical sensing interface opens up a reliable way for ultrasensitive detection of protein molecules,and some materials of MOFs series have The ability to recognize some groups。

The application of Photoelectrochemical sensors in environmental detection mainly includes heavy metal ions,organic arsenic pollution,organic pesticides and so on.Hg²⁺is seriously harmful to human health and may cause brain injury and other chronic diseases.Zhang et al.Developed a highly sensitive and selective Photoelectrochemical sensing interface for Hg²⁺based on the in situ formation of p-n junction(HgS)on ZnS surface,with a detection range of 0.01–100 nmol/L^[27]。 RGO can improve the separation of photogenerated electrons and holes,and cooperate with PCN-224 to amplify the photocurrent signal.arsenic aminophenate(p-ASA)is an organic Arsenic pollutant.the combination of p-ASA can adjust the band position of PCN-224/RGO and release more photogenerated electrons to enhance the photocurrent signal.Peng et al.Prepared PCN-224/RGO nanocomposite and used it for the Photoelectrochemical selective detection of p-ASA,and the detection limit of p-ASA reached 5.47 ng/L,which realized the monitoring of p-ASA in pig manure filtrate and natural water^[15]。

Pesticide residue is an important problem of environmental hazards,so rapid and sensitive methods for pesticide residue analysis have attracted much attention.Jin et al.Prepared a NH₂-MIL-125/TiO₂hybrid material for the Photoelectrochemical detection of the herbicide clethodim,and the sensor had a detection limit of 10 nmol/L,which was successfully used for the detection of methoprene in soil^[71]。 Cao et al.Constructed a Photoelectrochemical sensing interface based on hierarchical porous Cu-BTC MOF/g-C₃N₄nanosheet composites,and the hierarchical porous structure of Cu-BTC MOF/g-C₃N₄can effectively capture appropriate pesticide molecules and accelerate signal transmission.Under the irradiation of visible light,the Cu metal center coordinates with glyphosate to form a Cu-glyphosate complex,which leads to the increase of steric hindrance of electron transfer and the decrease of photocurrent signals,thus realizing the sensitive detection of non-electroactive glyphosate^[72]。 Its detection limit and detection range were 1.3×10^-13mol/L and 1.0×10^-12~1.0×10^-3mol/L,respectively.In view of the applications of MOFs-based composites in environmental research fields such as heavy metal adsorption,organic pollutant removal,and harmful gas capture,it will be challenging to comprehensively develop MOFs-based Photoelectrochemical sensing platforms integrated with environmental detection and remediation 。