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The synthesis and characterization of co-doped mesoporous nanocomposites consisting of zinc oxide (ZnO) and multi-walled carbon nanotubes (MWCNT) have been conducted. The synthesis has been carried out using a microwave-assisted hydrothermal approach. The confirmation of the formation of nanocomposites exhibiting a mesoporous morphology has been established through the utilization of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As per the energy dispersive X-ray (EDX) analysis, the synthesized samples contain nitrogen (N), carbon (C), silver (Ag), and iron (Fe) elements. The Brunauer-Emmett-Teller (BET) data analysis depicts class 4 hysteresis with 3.69 nm pore diameter and 21.52 m2/g surface area. The impact of co-doping nitrogen, silver, and iron on the reduction in energy band gap (3.2 to 2.6 eV) and electron-hole recombination has been illustrated using photoluminescence and UV-Vis spectroscopy. Furthermore, co-doped ZnO/MWCNT nanocomposites exhibit improved photocatalytic performance, with 94% and 98% degradation of congo red and methylene blue dyes, respectively. [ABSTRACT FROM AUTHOR]

In this study, we synthesized Cu and Co co-doped ZnO nanoparticles, denoted as Zn 1-2x Cu x Co x O (x = 0.01, 0.02, 0.03), using the sol-gel auto-combustion method. Successful integration of Cu and Co elements into the ZnO host lattice was confirmed through a comprehensive array of spectroscopic techniques. Structural analysis revealed the persistence of a hexagonal wurtzite crystal structure with some distinct microstructural variations across all samples. Alteration in lattice parameters and dislocation density strongly suggests the successful incorporation of Cu2+ and Co2+ ions within the ZnO lattice. A prominent increase in crystallite size from 27.19 nm to 33.46 nm was observed with the increase in doping concentration. Field emission scanning electron microscopy showed a combination of uniformly distributed spherical and hexagon-like structures. Furthermore, UV–Visible absorption spectra demonstrated a proportional enhancement in energy band gap from 2.14 eV for Zn 0.98 Cu 0.01 Co 0.01 O to 2.40 eV for Zn 0.94 Cu 0.03 Co 0.03 O. The Burstein−Moss effect was invoked to elucidate the observed blue shift in absorption spectra and energy band gaps, further solidifying our findings. The systematic and substantial correlation between dopant concentration and energy band gap signifies that the co-doping of Cu and Co is a viable strategy for engineering the band gap of ZnO. This collective investigation unveils the substantial potential of Cu and Co co-doping in ZnO nanoparticles for advanced optoelectronic applications, paving the way for tailored optical and photonic functionalities. • Cu and Co co-doping in ZnO offers potential for tailored optoelectronic applications. • Increasing dopant concentration enlarges crystallite size and widens the energy band gap. • Cu and Co co-doping modifies ZnO's properties, confirmed by spectroscopic analysis. [ABSTRACT FROM AUTHOR]

Ternary alloys of Zn 0.78 Cd 0.22 S nanoparticles (NPs) are synthesized via the facile co-precipitation technique. The as-synthesized sample exhibits a zincblende-type cubic phase with an average crystalline size of 2 nm. Thermal annealing and UV irradiation are utilized as post-treatment processes for tailoring the optical properties of Zn 0.78 Cd 0.22 S NPs. The as-synthesized sample exhibits a stable cubic phase up to 400 °C, during which partial phase transformation to a hexagonal structure is observed at a higher temperature of 500 °C. The oxidation of Zn 0.78 Cd 0.22 S NPs to mixed oxide phases with the majority of ZnO begins at 600 °C which induces morphology transformation to a relatively large nano-hexagon with a single crystalline domain size. The increase of the annealing temperature is accompanied by a decrease of Zn 0.78 Cd 0.22 S NPs optical band gap (E g) due to the weakness of size confinement as well as the formation of localized states below the mobility band edges. The brief UV irradiation results in the increase of E g whereas a further increase in exposure time is accompanied by a reduction of E g. The photoluminescence (PL) spectrum of the as-synthesized sample covers a wide spectral range from UV to visible. Thermal annealing has a slight effect on the PL emission at high excitation energy, whereas low excitation energy reveals higher sensitivity to deep-state emission. Thermal oxidation incorporates a high concentration of oxygen-related defects that induce strong enhancement in the green emission at the expense of UV emission. This indicates the thermal-induced bleaching of shallow trapping sites and the evolution of other deep trapping or recombination sites. • Homogeneous Zn 0.78 Cd 0.22 S nano-alloys are synthesized via a co-precipitation technique. • Thermal annealing results in the morphological transformation from nanoparticle to large nano-hexagon. • Thermal annealing results in a dramatic increase in the green emission intensity. • Photoluminescence of Zn 0.78 Cd 0.22 S NPs exhibits dependence on excitation energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal technique was utilized to fabricate yttrium doped ZnO nanorods. • The bandgap of the ZnO nanorods was significantly altered by doping yttrium. • The Y-doped ZnO nanorods degraded 97 % of MB dye under visible-light. • Super oxide radicals and holes play a dominant role in the degradation of MB. The hydrothermal technique was utilized to fabricate yttrium doped ZnO nanorods (Y-doped ZnO). Various spectroscopic approaches were used to examine the effect of yttrium doping on the crystal structure, shape, energy bandgap, and photocatalytic performance of ZnO nanorods. The fact that Y-doped ZnO nanocatalysts had the same hexagonal wurtzite crystal structure and nanorod shape as like undoped ZnO, signifying that doped yttrium ions have no effect on the structural as well as morphological features of ZnO nanorods. By doping yttrium into the ZnO sites, the bandgap energy of the ZnO nanorods was significantly altered, and the photodegradation activity was improved. The absorption edge of the Y-doped ZnO nanorods was shifted towards the higher wavelengths and blue shift in bandgap was observed. It has been confirmed that yttrium doping increases the light sensitivity of ZnO in the visible region while providing several active charge transporters on the nanorods surface as well. The photocatalytic activity of Y-doped ZnO nanocatalysts was significantly increased by generated charge carriers. For doping concentrations of 1 %, 3 % and 5 %, the photodegradation activity of Y-doped ZnO nanorods is 71 %, 97 %, and 82 %, respectively, whereas the photodegradation efficiency of pure ZnO nanorods is 22 %. The photodegradation efficiency of ZnO:Y3 was found to be 4.4 times higher than the pristine ZnO nanorods. In addition to the photodegradation, the Y-doped ZnO nanorods are anticipated to offer a valued platform to the widespread applications in the field of photocatalysis like electrochemical water splitting, hydrogen production and supercapacitors. [ABSTRACT FROM AUTHOR]

For further uptake in the solar cell industry, n-ZnO/p-Si single heterojunction solar cell has attracted much attention of the research community in recent years. This paper reports the influence of bandgap and/or electron affinity tuning of zinc oxide on the performance of n-ZnO/p-Si single heterojunction photovoltaic cell using PC1D simulations. The simulation results reveal that the open circuit voltage and fill factor can be improved significantly by optimizing valence-band and conduction-band off-sets by engineering the bandgap and electron affinity of zinc oxide. An overall conversion efficiency of more than 20.3% can be achieved without additional cost or any change in device structure. It has been found that the improvement in efficiency is mainly due to reduction in conduction band offset that has a significant influence on minority carrier current. [ABSTRACT FROM AUTHOR]