Heterostructures of Ni(II)-doped CdS quantum dots and β-Pb0.33V2O5 nanowires: Enhanced charge separation and redox photocatalysis via doping of QDs

IF 9 2区 材料科学 Q1 CHEMISTRY, PHYSICAL
Karoline E. García-Pedraza, Jaime R. Ayala, Udani Wijethunga, Alice R. Giem, George Agbeworvi, Sarbajit Banerjee, David F. Watson
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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.

Ni(II)掺杂CdS量子点和β-Pb0.33V2O5纳米线的异质结构:通过掺杂量子点增强电荷分离和氧化还原光催化
以l -半胱氨酸为分子连接剂,将Ni(II)掺杂的CdS (Ni:CdS)量子点(QDs)系在β-Pb0.33V2O5纳米线(NWs)上,合成了异质结构,并评价了掺杂对其氧化还原光催化活性的影响。我们最初假设,将Ni:CdS量子点加入异质结构可以改变激发态动力学和机制,并且激发态电子在Ni三维态上的定位可以促进包括CO2还原在内的氧化还原光催化机制。分离的Ni:CdS量子点具有铁磁性,相对于未掺杂的CdS量子点,它们表现出更强的光催化析氢和光稳定性。Pb0.33V2O5/CdS异质结构(未掺杂量子点)和Pb0.33V2O5/Ni:CdS异质结构(掺杂Ni(II)量子点)在量子点的价带态和β-Pb0.33V2O5 NWs的插层中隙态之间表现出大量的能量重叠。在Pb0.33V2O5/CdS异质结构中,CdS量子点光激发后空穴和电子快速(50-100 ps)转移到β-Pb0.33V2O5 NWs。相比之下,在Pb0.33V2O5/Ni:CdS异质结构中,空穴在100 ps内从Ni:CdS量子点转移到β-Pb0.33V2O5 NWs,但电子转移速度要慢约20倍。这种电子和空穴转移动力学的差异促进了电荷在Pb0.33V2O5/Ni:CdS界面上的分离,并使CO2光催化还原为CO、CH4和HCO2H,相对于H+还原为H2,其选择性为99.9%。这些结果强调了通过在异质结构中掺杂量子点来微调激发态电荷转移的动力学和机制,以及随后的氧化还原半反应机制的机会。此外,它们还揭示了含有量子点和MxVyO5材料的异质结构作为co2还原光催化剂的前景。
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来源期刊
Nano Research
Nano Research 化学-材料科学:综合
CiteScore
14.30
自引率
11.10%
发文量
2574
审稿时长
1.7 months
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.
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