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

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%.

Laser Ablation Nanoarchitectonics of Au–Cu Alloys Deposited on TiO2 Photocatalyst Films for Switchable Hydrogen Evolution from Formic Acid Dehydrogenation

“…The smaller radius in the EIS Nyquist plot indicates a lower R et of the electrodes. On the contrary, the relatively small R et of Cu/TiO 2 can be affected by Cu 2 O on its surface, probably behaving as a semiconductor to induce the electron transfer . Based on the fitting analysis using the equivalent circuit model, the Au/TiO 2 , Au 50 Cu 50 /TiO 2 , and Au 20 Cu 80 /TiO 2 photocatalysts show R re values of 184, 345, and 513 Ω, respectively, that are smaller than Au 10 Cu 90 /TiO 2 (1051 Ω) and Au 5 Cu 95 /TiO 2 (628 Ω).…”

“…On the contrary, the relatively small R et of Cu/TiO 2 can be affected by Cu 2 O on its surface, probably behaving as a semiconductor to induce the electron transfer. 60 Based on the fitting analysis using the equivalent circuit model, the Au/TiO 2 , Au 50 Cu 50 /TiO 2 , and Au 20 Cu 80 /TiO 2 photocatalysts show R re values of 184, 345, and 513 Ω, respectively, that are smaller than Au 10 Cu 90 /TiO 2 (1051 Ω) and Au 5 Cu 95 /TiO 2 (628 Ω). An additional arc observed at the region of R re for Au 5 Cu 95 /TiO 2 can be attributed to the Cu + leaching from Au 5 Cu 95 NPs.…”

Synthesis of cuprous oxide/silver (Cu 2 O/Ag) hybrid as surface-enhanced Raman scattering probe for trace determination of methyl orange

“…Figure 7 a illustrates the PL spectra of Cu 2 O and Cu 2 O/Ag x composites under 325 nm excitation. A distinct narrow peak at 670 nm for all samples is found, which can be indexed to free exciton recombination of Cu 2 O [ 60 ]. Cu 2 O microcubes sample shows the highest PL intensity on account of the quickest recombination of charge carriers.…”

Trace Amounts of Co3O4 Nano-Particles Modified TiO2 Nanorod Arrays for Boosted Photoelectrocatalytic Removal of Organic Pollutants in Water

“…TiO 2 is a n-type semiconductor and, combined with a p-type semiconductor in a suitable band gap position to form a p-n heterojunction, it is an effective tactic to expand light absorption, enhance the separation effects of electrons and holes, prolong the lifetime of the electron and hole, and heighten the photocatalytic activity. Transition metal oxides, such as Ag 2 O, Cu 2 O, CuO, and Co 3 O 4 , have been used to form a p-n junction to promote an interfacial electron transfer process and increase the separation effect [ 18 , 22 , 23 , 24 ]. Cobalt oxides have received attention because of their excellent photo-catalytic activity in carbon dioxide reduction, oxygen reduction, and environment restoration [ 25 , 26 ].…”