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[Display omitted] • CoS 2 /CdS with 0D/1D heterostructure was fabricated by growing CoS 2 QDs on CdS NWs. • CoS 2 QDs and CdS NWs separately act as chlorpyrifos-recognition probe and PEC sensitizer. • A visible-light-driven PEC sensor was developed for the analysis of chlorpyrifos. • The PEC sensor can detect chlorpyrifos with concentrations down to 0.010 ppb. A visible-light-responsive photoelectrochemical (PEC) sensor was proposed for the sensitive and selective analysis of chlorpyrifos (CPF) by synergistically using CoS 2 quantum dots (QDs) and CdS nanowires (NWs). The CdS NWs were first prepared by the solvothermal method and subsequently combined with CoS 2 QDs to produce CoS 2 /CdS product with 0D/1D heterostructure. It turned out that the so-obtained nanocomposites with 0D/1D heterostructure could greatly suppress the recombination of photoinduced electrons and holes, and the electrode modified with this composite could exhibit preferable PEC performance and photocurrent signal compared to the one with CdS or CoS 2. After the addition of CPF, the photocurrent signal of the proposed PEC sensor was found to be selectively decreased because of the specific chelation between the cobalt sites of CoS 2 /CdS and the sulfur, nitrogen-atoms of CPF, which might block the electrons transferring process. The proposed PEC sensor could detect CPF in concentrations that linearly span from 0.030 to 100 ppb with an ideal detection limit of 0.010 ppb, which performances are much better than those of currently used analytical methods. Furthermore, this work may establish a framework for the development of various PEC sensing platforms with 0D/1D heterostructure for the quantitative assay of environmental pollutants like CPF. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnS/CdS was fabricated with type-II heterostructure by growing ZnS QDs on CdS NWs. • Low-bandgap CdS NWs and wide-bandgap ZnS QDs act separately as photosensitizer and Hg2+ probe. • A selective PEC sensor was developed for the analysis of Hg2+ with "turn-on" signal output. • Hg2+ induces the in-situ formation of HgS/ZnS/CdS with double type-II heterostructure. • The PEC sensor can detect Hg2+ with concentrations down to about 0.40 pM. An ultrasensitive and selective photoelectrochemical (PEC) platform has been developed for determining Hg2+ with "turn-on" signal output by synergistically using CdS nanowires (NWs) and ZnS quantum dots (QDs). CdS NWs was first prepared and then deposited with ZnS QDs to yield ZnS/CdS nanocomposite with type-II heterostructure. It was found that the as-constructed ZnS/CdS heterostructure can exhibit excellent photoelectrochemical characteristics by separately employing CdS NWs and ZnS QDs as the photosensitizer and Hg2+-recognition probe. What's more, the constructed analysis platform could display specifically enhanced photocurrent responses to Hg2+ under the visible light via the selective ion-exchange reaction. The in-situ formation of ternary HgS/ZnS/CdS could be thus expected with double type-II heterostructures so as to further enhance the transferring and separation of charges. A linear response can be achieved for Hg2+ in the concentration range from 0.0010 to 5.0 nM, with a detection limit of 0.40 pM. Moreover, the application feasibility of the developed sensor with ZnS/CdS heterostructure could be testified by detecting Hg2+ ions in environmental waters. Such a route of in-situ formation of double type-II heterostructure might promise the wide applications for designing different visible light-driven PEC sensors for probing heavy metals like Hg2+ with the "turn-on" signal output. [ABSTRACT FROM AUTHOR]

A highly sensitive and visible-light-driven photoelectrochemical (PEC) sensor has been constructed for the quantitative assay of organophosphorus pesticides like chlorpyrifos (Chlo) using hollow Co 9 S 8 @CdS heterostructures. The Co 9 S 8 @CdS heterostructures were created by growing CdS onto Co 9 S 8 surface via one-step oil-bath route, of which Co 9 S 8 was fabricated with hollow tubular structures through the Co(CO 3) 0.35 Cl 0.2 (OH) 1.1 -templated solvothermal method. It was discovered that the so-obtained Co 9 S 8 @CdS with direct Z-scheme heterojunctions could exhibit larger photocurrents than the Co 9 S 8 or CdS because of the greatly enhanced separation efficiency of photo-generated carriers. What's more, the photocurrent signal of Co 9 S 8 @CdS-based PEC sensor could be selectively inhibited with the addition of Chlo through the specific chelation between the N and S atoms of Chlo with C N and P S groups and Co sites of Co 9 S 8 @CdS so as to suppress the carriers transferring. The developed PEC sensor could exhibit a linear response for Chlo ranging from 0.050 to 1000 ppb, with the detection limit value down to 0.015 ppb, which was far below than those of currently reported PEC sensors. Besides, the proposed routes may provide guidelines for designing various direct Z-scheme heterojunction-based PEC analysis platforms for determining environmental pollutants like Chlo. [Display omitted] • A visible-light-driven photoelectrochemical sensor was developed for probing chlorpyrifos. • Hollow Co 9 S 8 @CdS heterostructures were constructed via one-pot oil-bath route. • Co 9 S 8 and CdS were separately utilized as chlorpyrifos-recognition probe and sensitizer. • The sensor can facilitate the detection of chlorpyrifos with concentration down to 0.015 ppb. [ABSTRACT FROM AUTHOR]

• A near-infrared-light-driven photoelectrochemical sensor is developed for probing Hg2+. • Bead chain-like Ag@Ag 2 S composites are prepared via one-step oil-bath route followed by photoreduction. • Ag 2 S and metallic Ag separately act as the sensitizer and Hg2+-recognition probe. • This PEC sensor can facilitate the detection of Hg2+ with concentrations down to 0.50 pM. A near-infrared (NIR) light-driven photoelectrochemical (PEC) sensing platform was established for the quantitative assay of Hg2+ using Ag@Ag 2 S nanocomposites. Ag 2 S quantum dots (QDs) with the bead-chain-like nanostructure were fabricated simply via one-step oil-bath route to be further deposited with metallic Ag through the photo-reduction method to yield Ag@Ag 2 S nanocomposites. It was found that Ag@Ag 2 S-based sensor could present more than twice larger PEC responses than the Ag 2 S-based one, due to the synergetic combination of metallic Ag with the surface plasmon resonance (SPR) effects and Ag 2 S QDs with the NIR-light-irradiated PEC properties. More importantly, the developed PEC sensor could display the photocurrent responses that are selectively inhibited in the presence of Hg2+ by forming Ag-Hg amalgam to accelerate the recombination of photo-induced electron-hole pairs. Under NIR light, it can detect Hg2+ in the concentrations linearly ranging from 0.0010 to 5.0 nM, with a limit of detection of about 0.50 pM. This work may guide a promising combination of Ag 2 S of NIR QDs with metallic Ag of SPR effects for designing various PEC sensing platforms for the complex environmental monitoring of different heavy-metal ions like Hg2+. [ABSTRACT FROM AUTHOR]

• A photoelectrochemical sensor was developed for the "signal-on" analysis of Hg2+. • Hollow CoS x @CdS polyhedrons were fabricated by ZIF-67-templated solvothermal route. • Direct Z-scheme CoS x @CdS photocatalysts were utilized as the recognition probes. • New Z-scheme heterojunction of CoS x @CdS/HgS was formed by the selective ion-exchange. • This PEC sensor can facilitate the detection of Hg2+ with concentrations down to 2.0 pM. A visible-light-driven photoelectrochemical (PEC) sensor has been developed for probing Hg2+ with "turn-on" signal output using hollow CoS x @CdS polyhedron as direct Z-scheme photocatalyst and Hg2+-recognition probe. The CoS x @CdS heterojunction photocatalysts were fabricated by growing CdS nanoparticles on the surface of cobalt sulfide (CoS x) via one-pot solvothermal route using metal-organic frameworks (MOFs) of ZIF-67 polyhedrons as the sacrificial templates and cobalt precursors. It was discovered that the photocurrent responses of the CoS x @CdS-modified ITO electrodes could be specifically turned on by Hg2+, in contrast to these of the CoS x or CdS-modified ones showing no significant Hg2+-induced photocurrent. Under visible light irradiation, herein, the synergetic combination of CoS x and CdS components could improve the carriers transferring of PEC system. More importantly, the photocurrents of the PEC sensor could be greatly enhanced in the presence of Hg2+ through the selective ion-exchange reaction to trigger the in-situ formation of a new Z-scheme heterojunction of CoS x @CdS/HgS photocatalysts, achieving the further promoted charge transferring and suppressed recombination of photogenerated electron-hole pairs. The developed double heterojunctions-based PEC sensors can detect Hg2+ with the concentrations ranging from 0.010 to 1000 nM, which performances are much better than those of the current PEC analysis methods. Besides, such a MOF-templated one-pot construction route may pave the way toward the design of various direct Z-scheme heterojunction photocatalysts of PEC probes of great interest. [ABSTRACT FROM AUTHOR]

• A photoelectrochemical sensor was developed for the "signal-on" analysis of Hg2+. • Bead chain-like Ag 2 S were integrated with ZnS to be coated onto the ITO electrodes. • Ag 2 S and ZnS were utilized separately as the sensitizer and recognition probe. • Hg2+ can conduct a Zn-to-Hg exchange to form HgS/ZnS@Ag 2 S heterojunction. • This sensor can facilitate the detection of Hg2+ with concentrations down to 1.0 pM. A visible-light-driven photoelectrochemical (PEC) sensor has been developed for the "signal-on" analysis of Hg2+ by the synergetic combination of low-bandgap Ag 2 S and wide-bandgap ZnS quantum dots (QDs). Ag 2 S QDs were synthesized with bead-chain-like structure by the self-assembly route and further covalently bound with ZnS QDs to be coated onto the indium tin oxide (ITO) electrodes. It was discovered that the ZnS@Ag 2 S-modified electrodes could display the visible-light-driven PEC behavior, of which Ag 2 S and ZnS QDs could act as the PEC sensitizer and Hg2+-recognition probe, respectively. More importantly, the photocurrent responses of the developed electrodes could be specifically turned on in the presence of Hg2+ under the visible-light irradiation, presumably due to that Hg2+ might conduct a Zn-to-Hg exchange on ZnS QDs to trigger the formation of HgS/ZnS@Ag 2 S heterojunction towards the enhanced electron-hole separation. The as-prepared PEC sensor could facilitate the detection of Hg2+ with concentrations ranging from 0.010–1000 nM, with a detection limit of about 1.0 pM. Besides, the feasibility of practical applications of the developed PEC analysis strategy was verified by probing Hg2+ in environmental water samples. Such a visible-light-driven PEC detection platform with the unique "turn-on" signal output may promise for the extensive applications for Hg2+ evaluation. [ABSTRACT FROM AUTHOR]