High performance Cu_2O/ZnO core-shell nanorod arrays synthesized using a nanoimprint GaN template by the hydrothermal growth technique

Chuo

et al. 2019

Adv Materials Inter

Chemical solutions are applied to synthesize Au–Pd alloy nanoparticles (NPs) and ZnO/Cu2O core–shell nanowires (NWs) on ITO/glass substrates by the photochemical, electrochemistry, and hydrothermal methods. The Cu2O cubic structures and ZnO hexagonal wurtzite structures are verified as being polycrystalline and single crystalline, respectively, by X‐ray diffraction and high‐resolution transmission electron microscopy (HR‐TEM). The p‐Cu2O/n‐ZnO NWs samples exhibit rectification properties that confirm the p–n heterojunction interface. The diameter range of the Au–Pd alloy NPs is around 2–15 nm and the Au/Pd ratio is 27:28, according to HR‐TEM and X‐ray photoelectron spectroscopy. The p‐Cu2O/n‐ZnO core–shell NWs feature higher UV photocatalytic degradation of methylene blue than do the ZnO NWs. Deposited Au, Pd, Au–Pd alloy NPs on the p‐Cu2O/n‐ZnO core–shell NWs improve the photocatalytic degradation efficiency under UV and blue light. The Au–Pd alloy NPs/p‐Cu2O/n‐ZnO core–shell NWs offer the best photocatalytic properties under UV‐ and blue‐light‐emitting diode (LED) illumination.

Section: Resultsmentioning

confidence: 99%

UV and Visible Light Induced Photocatalytic Degradation on p–n Cu₂O/ZnO Nanowires Decorated with Au–Pd Alloy Nanoparticles

Chuo

et al. 2019

Adv Materials Inter

“…These approaches undoubtedly offer numerous benefits, but they still suffer from a number of drawbacks, such as low detection accuracy, time consumption, complicated procedure, and high cost. To solve these problems, we use a p-n diode structure composed of Cu 2 O and ZnO NRs as a self-powered biosensor, whose structure has already been proven to have excellent photocatalytic performance [22,23] and PEC properties [24][25][26]. As the sensitivity of a biosensor is determined by crystal quality [27], the addition of hexamethylenetetramine (HMTA) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) presents several advantages, including the following: (1) improved crystallization of Cu 2 O and ZnO, (2) enhanced broad absorption of visible light, and (3) higher PEC performance than the Cu 2 O/ZnO heterostructure in terms of electron-pair separation efficiency.…”

Section: Introductionmentioning

confidence: 99%

Cu2O/PEDOT:PSS/ZnO Nanocomposite Material Biosensor for Esophageal Cancer Detection

Tseng

Hsiao

Jen

et al. 2020

Sensors

Self Cite

A highly sensitive photoelectrochemical (PEC) biosensor without external bias was developed in this study. The biosensor was configured with a p-Cu2O and n-ZnO heterostructure. Hexamethylenetetramine (HMTA) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was used to improve the crystal structure of Cu2O and ZnO and reduce the defects in the Cu2O/ZnO interface. This fabrication method provided the highly crystallized Cu2O/ZnO structure with excellent electrical property and photoresponse in visible light. The structure was applied to a biosensor for detecting two different cancerous levels of esophageal cells, namely, OE21 and OE21-1, with a high gain in photocurrent (5.8 and 6.2 times, respectively) and a low detection limit (3000 cells in 50 μL). We believe that such a p-n heterojunction PEC biosensor could advance biosensor development and provide a promising candidate for biomedical applications.

“…Intrinsic strain is originated from high-density crystallographic imperfections in ZnO. Crystallographic imperfections include hydrogen complexes, zinc interstitials (Zn i ), oxygen vacancies (V O ), threading dislocations (TDs), and grain boundaries (GBs) [ 10 – 21 ]. Extrinsic strain is generated from a large mismatch of lattice constants and thermal expansion coefficients between ZnO epilayer and sapphire substrate.…”

Section: Introductionmentioning

confidence: 99%

Co-dosing Ozone and Deionized Water as Oxidant Precursors of ZnO Thin Film Growth by Atomic Layer Deposition

et al. 2020

Self Cite

Characteristics of atomic layer deposition (ALD)-grown ZnO thin films on sapphire substrates with and without three-pulsed ozone (O 3 ) as oxidant precursor and post-deposition thermal annealing (TA) are investigated. Deposition temperature and thickness of ZnO epilayers are 180 °C and 85 nm, respectively. Post-deposition thermal annealing is conducted at 300 °C in the ambience of oxygen (O 2 ) for 1 h. With strong oxidizing agent O 3 and post-deposition TA in growing ZnO, intrinsic strain and stress are reduced to 0.49% and 2.22 GPa, respectively, with extremely low background electron concentration (9.4 × 10 15 cm −3 ). This is originated from a lower density of thermally activated defects in the analyses of thermal quenching of the integrated intensity of photoluminescence (PL) spectra. TA further facilitates recrystallization forming more defect-free grains and then reduces strain and stress state causing a remarkable decrease of electron concentration and melioration of surface roughness.