Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Mar 27;5(13):7503-7518.
doi: 10.1021/acsomega.0c00299. eCollection 2020 Apr 7.

Au-Mediated Charge Transfer Process of Ternary Cu2O/Au/TiO2-NAs Nanoheterostructures for Improved Photoelectrochemical Performance

Zhufeng Shao  1 , Yufeng Zhang  1 , Xiujuan Yang  1 , Min Zhong  1
Affiliations

Au-Mediated Charge Transfer Process of Ternary Cu2O/Au/TiO2-NAs Nanoheterostructures for Improved Photoelectrochemical Performance

Zhufeng Shao et al. ACS Omega. .

Abstract

Based on a facile three-step preparation method, Cu2O/Au/TiO2-NAs ternary heterojunction nanocomposites have been successfully synthesized by electrodepositing a Cu2O layer on the surface of Au nanoparticles (NPs) decorated highly ordered TiO2 nanotube arrays (NAs). The structure, surface morphology, chemical composition, and optical and intrinsic defects properties of the as-prepared samples are characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD), UV-vis light absorbance spectra, Raman scattering, and X-ray photoelectron spectroscopy (XPS). Simultaneously, the Cu2O/Au/TiO2-NAs ternary nanohybrids exhibited progressively improved photoelectrocatalytic (PEC) performance compared with the dual Cu2O/TiO2-NAs type-II nanoheterojunctions, confirming by the photocurrent density versus testing time curve (amperometric I-t curve), open-circuit potential versus testing time curve (V oc-t curve), and electrochemical impedance spectroscopy (EIS) measurements, which were mainly ascribed to the synergistic effect of reduced interfacial charge transfer resistance and boosted energetic charge carriers generation associated with embedding Au NPs. Furthermore, the self-consistent charge transfer mechanism of Z-scheme and interband transitions mediated with Au NPs for Cu2O/Au/TiO2-NAs triple nanocomposites is proposed, which was evaluated by nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra excited by 266 and 400 nm, respectively. Following this scheme, UV-vis light photocatalytic activities of Cu2O/Au/TiO2-NAs ternary nanohybrids were elaborated toward photodegradation of methyl orange (MO) in aqueous solution, and the photodegradation rate of optimum triple nanocomplex was found to be 90%.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Morphological characterization of pristine TiO2 nanotube array (TiO2-NAs) films, Au/TiO2-NAs, Cu2O/TiO2-NAs, and Cu2O/Au/TiO2-NAs nanoheterojunction complex, respectively. (a) SEM pictures of as-formed pristine TiO2-NAs with cross-sectional microstructures (inset) and TEM picture for single TiO2 nanotube (inset). (b) Top-view SEM image of Au/TiO2-NAs. (c) SEM pictures of as-fabricated Cu2O/TiO2-NAs with cross-sectional microstructures (inset). (d–f) Top-view SEM images of Cu2O/Au/TiO2-NAs with Cu2O deposited times of 20, 40, and 80 s, respectively.
Figure 2
Figure 2
Energy-dispersive X-ray fluorescence spectrum (EDXRF) of Au/TiO2-NAs and ternary Cu2O/Au/TiO2-NAs nanoheterojunctions with different Cu2O electrochemical deposition times (20, 40, and 80 s).
Figure 3
Figure 3
(a) Three-dimensional and (b) two-dimensional nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra of the binary Cu2O/TiO2-NAs nanocomposites, respectively.
Figure 4
Figure 4
NTRT-PL spectra of the ternary nanosized Cu2O/Au/TiO2-NAs heterojunction films deposited Cu2O with different times of (a) 20 s, (b) 40 s, and (c) 80 s excited at 266 nm, respectively.
Figure 5
Figure 5
Schematic illustration of (a) band gap structure for individual Cu2O and TiO2 semiconductors before contact, (b) band gap structure for binary Cu2O/TiO2-NAs nanoheterojunctions, (c) photogenerated charge carriers excited and traditional type-II transient transfer pathway for Cu2O/TiO2-NAs nanocomposites under UVC light irradiation, and (d) photogenerated charge carriers Z-scheme transient transfer for ternary Cu2O/Au/TiO2-NAs nanohybrids under UVC light irradiation.
Figure 6
Figure 6
NTRT-PL spectra for (a) binary Cu2O/TiO2-NAs nanoheterojunctions and ternary nanosized Cu2O/Au/TiO2-NAs nanoheterojunctions deposited Cu2O with different times of (b) 20 s, (c) 40 s, and (d) 80 s under irradiation of monochromatic wavelength at 400 nm, respectively.
Figure 7
Figure 7
Schematic illustration of (a) band gap structure for aerated Cu2O and TiO2-NAs after contact, (b) traditional type-II CT for binary Cu2O/TiO2-NAs nanoheterojunctions under 400 nm irradiation, (c) band gap structure for ternary Cu2O/Au/TiO2-NAs nanocomplex without no illumination, and (d) plasmon-induced interfacial CT (PICT) for ternary Cu2O/Au/TiO2-NAs nanohybrids irradiated by 400 nm.
Scheme 1
Scheme 1. Schematic Diagram for the Photodegradation of MO over the Cu2O/TiO2-NAs Type-II Heterojunction System under UV–Vis Light Irradiation
Figure 8
Figure 8
Photodegradation rate η of MO, the pristine TiO2-NAs, Cu2O/TiO2-NAs, and Cu2O/Au/TiO2-NAs with different Cu2O times (20, 40, and 80s) irradiated with a UV–vis lamp, respectively.
Figure 9
Figure 9
Plot of ln(C0/Ct) versus irradiation time of MO degradation for MO, the pristine TiO2-NAs, Cu2O/TiO2-NAs, and Cu2O/Au/TiO2-NAs with different Cu2O times (20, 40, and 80 s) irradiated with a UV–vis lamp.
Figure 10
Figure 10
Cyclic photodegradation efficiency of the MO, the pristine TiO2-NAs, Cu2O/TiO2-NAs, and Cu2O/Au/TiO2-NAs with different Cu2O deposition times (20, 40, and 80 s) heterojunction nanocomplex irradiated by UV–vis light under the same conditions six times, respectively.
Scheme 2
Scheme 2. Synthetic Procedures for Preparation of (a) Dual Type-II Cu2O/TiO2-NAs Nanoheterojunctions and (b) Ternary Cu2O/Au/TiO2-NAs Nanohybrids, respectively
Figure 11
Figure 11
Experiment setup of nanosecond time-resolved transient PL (NTRT-PL) measurements.
See this image and copyright information in PMC

References

    1. Fujishima A.; Honda K. Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature 1972, 238, 37–38. 10.1038/238037a0. - DOI - PubMed
    1. Chiu Y.-H.; Chang T.-F. M.; Chen C.-Y.; Sone M.; Hsu Y.-J. Mechanistic Insights into Photodegradation of Organic Dyes Using Heterostructure Photocatalysts. Catalysts 2019, 9, 430.10.3390/catal9050430. - DOI
    1. Hsieh P.-Y.; Chiu Y.-H.; Lai T.-H.; Fang M.-J.; Wang Y.-T.; Hsu Y.-J. TiO2 Nanowire-Supported Sulfide Hybrid Photocatalysts for Durable Solar Hydrogen Production. ACS Appl. Mater. Interfaces 2019, 11, 3006–3015. 10.1021/acsami.8b17858. - DOI - PubMed
    1. Chiu Y.-H.; Lai T.-H.; Chen C.-Y.; Hsieh P.-Y.; Ozasa K.; Niinomi M.; Okada K.; Chang T.-F. M.; Matsushita N.; Sone M.; Hsu Y.-J. Fully Depleted Ti–Nb–Ta–Zr–O Nanotubes: Interfacial Charge Dynamics and Solar Hydrogen Production. ACS Appl. Mater. Interfaces 2018, 10, 22997–23008. 10.1021/acsami.8b00727. - DOI - PubMed
    1. Gao D.; Wang Q.; Chang Y.; Jia Y.; Wang L.; Wang C. Solvothermal ion exchange preparation of Bi11VO19 to sensitize TiO2 NTs with high photoelectrochemical performances. Sep. Purif. Technol. 2020, 233, 116011.10.1016/j.seppur.2019.116011. - DOI