Karoline E. García-Pedraza, Jaime R. Ayala, Udani Wijethunga, Alice R. Giem, George Agbeworvi, Sarbajit Banerjee, David F. Watson
{"title":"Heterostructures of Ni(II)-doped CdS quantum dots and β-Pb0.33V2O5 nanowires: Enhanced charge separation and redox photocatalysis via doping of QDs","authors":"Karoline E. García-Pedraza, Jaime R. Ayala, Udani Wijethunga, Alice R. Giem, George Agbeworvi, Sarbajit Banerjee, David F. Watson","doi":"10.1007/s12274-024-6675-5","DOIUrl":null,"url":null,"abstract":"<div><p>We synthesized heterostructures by tethering Ni(II)-doped CdS (Ni:CdS) quantum dots (QDs) to β-Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub> nanowires (NWs) using L-cysteine as a molecular linker, and we evaluated the influence of doping on their redox photocatalytic reactivity. We initially hypothesized that incorporating Ni:CdS QDs into heterostructures could alter excited-state dynamics and mechanisms, and that the localization of excited electrons on Ni 3d states could promote redox photocatalytic mechanisms including reduction of CO<sub>2</sub>. Isolated Ni:CdS QDs were ferromagnetic, and they exhibited enhanced photocatalytic hydrogen evolution and photostability relative to undoped CdS QDs. Both Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub>/CdS heterostructures (with undoped QDs) and Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub>/Ni:CdS heterostructures (with Ni(II)-doped QDs) exhibited substantial energetic overlap between valence-band states of QDs and intercalative mid-gap states of β-Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub> NWs. Within Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub>/CdS heterostructures, photoexcitation of CdS QDs was followed by rapid (50–100 ps) transfer of both holes and electrons to β-Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub> NWs. In contrast, within Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub>/Ni:CdS heterostructures, holes were transferred from Ni:CdS QDs to β-Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub> NWs within 100 ps, but electrons were transferred approximately 20-fold more slowly. This difference in electron- and hole-transfer kinetics promoted charge separation across the Pb<sub>0.33</sub>V<sub>2</sub>O<sub>5</sub>/Ni:CdS interface and enabled the photocatalytic reduction of CO<sub>2</sub> to CO, CH<sub>4</sub>, and HCO<sub>2</sub>H with > 99.9% selectivity relative to the reduction of H<sup>+</sup> to H<sub>2</sub>. These results highlight the opportunity to fine-tune dynamics and mechanisms of excited-state charge-transfer, and mechanisms of subsequent redox half-reactions, by doping QDs within heterostructures. Moreover, they reveal the promise of heterostructures comprising QDs and M<sub><i>x</i></sub>V<sub><i>y</i></sub>O<sub>5</sub> materials as CO<sub>2</sub>-reduction photocatalysts.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":713,"journal":{"name":"Nano Research","volume":"17 :","pages":"10279 - 10291"},"PeriodicalIF":9.0000,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nano Research","FirstCategoryId":"88","ListUrlMain":"https://link.springer.com/article/10.1007/s12274-024-6675-5","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
We synthesized heterostructures by tethering Ni(II)-doped CdS (Ni:CdS) quantum dots (QDs) to β-Pb0.33V2O5 nanowires (NWs) using L-cysteine as a molecular linker, and we evaluated the influence of doping on their redox photocatalytic reactivity. We initially hypothesized that incorporating Ni:CdS QDs into heterostructures could alter excited-state dynamics and mechanisms, and that the localization of excited electrons on Ni 3d states could promote redox photocatalytic mechanisms including reduction of CO2. Isolated Ni:CdS QDs were ferromagnetic, and they exhibited enhanced photocatalytic hydrogen evolution and photostability relative to undoped CdS QDs. Both Pb0.33V2O5/CdS heterostructures (with undoped QDs) and Pb0.33V2O5/Ni:CdS heterostructures (with Ni(II)-doped QDs) exhibited substantial energetic overlap between valence-band states of QDs and intercalative mid-gap states of β-Pb0.33V2O5 NWs. Within Pb0.33V2O5/CdS heterostructures, photoexcitation of CdS QDs was followed by rapid (50–100 ps) transfer of both holes and electrons to β-Pb0.33V2O5 NWs. In contrast, within Pb0.33V2O5/Ni:CdS heterostructures, holes were transferred from Ni:CdS QDs to β-Pb0.33V2O5 NWs within 100 ps, but electrons were transferred approximately 20-fold more slowly. This difference in electron- and hole-transfer kinetics promoted charge separation across the Pb0.33V2O5/Ni:CdS interface and enabled the photocatalytic reduction of CO2 to CO, CH4, and HCO2H with > 99.9% selectivity relative to the reduction of H+ to H2. These results highlight the opportunity to fine-tune dynamics and mechanisms of excited-state charge-transfer, and mechanisms of subsequent redox half-reactions, by doping QDs within heterostructures. Moreover, they reveal the promise of heterostructures comprising QDs and MxVyO5 materials as CO2-reduction photocatalysts.
期刊介绍:
Nano Research is a peer-reviewed, international and interdisciplinary research journal that focuses on all aspects of nanoscience and nanotechnology. It solicits submissions in various topical areas, from basic aspects of nanoscale materials to practical applications. The journal publishes articles on synthesis, characterization, and manipulation of nanomaterials; nanoscale physics, electrical transport, and quantum physics; scanning probe microscopy and spectroscopy; nanofluidics; nanosensors; nanoelectronics and molecular electronics; nano-optics, nano-optoelectronics, and nano-photonics; nanomagnetics; nanobiotechnology and nanomedicine; and nanoscale modeling and simulations. Nano Research offers readers a combination of authoritative and comprehensive Reviews, original cutting-edge research in Communication and Full Paper formats. The journal also prioritizes rapid review to ensure prompt publication.