“…2.3 eV), as above proven in Figure b. For the specimens of Cu 2 O/TiO 2 -NAs and Cu 2 O/Au/TiO 2 -NAs 80s, as seen in Figure a,d, there are three transient PL peaks, centering at 430, 535, and 675 nm, which originated from the shallow-trapping recombinative PL of single and doubly ionized OV defects in TiO 2 -NAs and Cu vacancies (Cu v ) acceptor level in Cu 2 O, respectively. Simultaneously, as illustrated in Figure b,c, besides transient PL peaks at 430 and 675 nm stated above, the fresh emerging PL peaks are located at 570 nm (ca.…”
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%.
“…2.3 eV), as above proven in Figure b. For the specimens of Cu 2 O/TiO 2 -NAs and Cu 2 O/Au/TiO 2 -NAs 80s, as seen in Figure a,d, there are three transient PL peaks, centering at 430, 535, and 675 nm, which originated from the shallow-trapping recombinative PL of single and doubly ionized OV defects in TiO 2 -NAs and Cu vacancies (Cu v ) acceptor level in Cu 2 O, respectively. Simultaneously, as illustrated in Figure b,c, besides transient PL peaks at 430 and 675 nm stated above, the fresh emerging PL peaks are located at 570 nm (ca.…”
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%.
“…It is believed that the oxygen vacancies and defects play a major role in the RTFM of semiconductor oxides [19][20][21][22]. Recently, Li et al [23] concluded that oxygen defects are the origin of the ferromagnetism in Yb-doped ZnO film.…”
“…It means that secondary oxides can be formed when the Cu doping level exceeds 1%, and this has been verified experimentally [20]. Further, some results found that secondary oxides and its related structures of Cu dopants can also contribute to the RTFM [12,21], which is a discrepancy from that reported before [22]. Hou et al found that porous Cu 2 O thin films manifest unexpectedly large RTFM, which was ascribed to coupling between oxygen vacancies and local magnetic moments [21].…”
Section: Introductionmentioning
confidence: 88%
“…Further, some results found that secondary oxides and its related structures of Cu dopants can also contribute to the RTFM [12,21], which is a discrepancy from that reported before [22]. Hou et al found that porous Cu 2 O thin films manifest unexpectedly large RTFM, which was ascribed to coupling between oxygen vacancies and local magnetic moments [21]. Gao et al reported that the RTFM of the CuO-ZnO system can be tuned by the interface counts for CuO and ZnO heterostructures [12].…”
To explore the origin of magnetism, the effect of light Cu-doping on ferromagnetic and photoluminescence properties of ZnO nanocrystals was investigated. These Cu-doped ZnO nanocrystals were prepared using a facile solution method. The Cu2+ and Cu+ ions were incorporated into Zn sites, as revealed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). At the Cu concentration of 0.25 at.%, the saturated magnetization reached the maximum and then decreased with increasing Cu concentration. With increasing Cu concentration, the photoluminescence (PL) spectroscopy indicated the distribution of VO+ and VO++ vacancies nearly unchanged. These results indicate that Cu ions can enhance the long-range ferromagnetic ordering at an ultralow concentration, but antiferromagnetic “Cu+-Vo-Cu2+” couples may also be generated, even at a very low Cu-doping concentration.
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