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Green hydrogen has an audible echo in the clean energy field. In this piece of work, pure and Mo-doped CuO thin films were deposited at different substrate temperatures on the Indium Tin Oxide (ITO) by the DC/RF sputtering technique. The prepared samples were utilized to generate hydrogen gas within the photoelectrochemical water-splitting mechanism. Crystallographic planes (−111), and (200) were the preferred orientations for pure and Mo-doped CuO thin films. Moreover, the average crystallite size was doubled by Mo doping reaching 25.8 nm. FE-SEM microscopic image exhibits that the pure and Mo–CuO thin films have a regular distribution with a small size. The optical band gap has rosed by doping from 1.8 eV to 2.05 eV. Then, it increased to 2.3 eV and 2.4 eV at temperatures of 100 °C and 200 °C respectively. Pure and Mo–CuO thin films were applied as photocathodes for hydrogen generation with water water-splitting technique. The photoelectrochemical application revealed a photocurrent density of ∼2.25 mA/cm2 for Mo-doped CuO photoelectrode at room temperature. This optimum photoelectrode was studied for stability and electrochemical impedance. In addition, the incident photon to current efficiency (IPCE%) was 4.47 % at 500 nm. The applied bias photon to current conversion efficiency (ABPE%) was 4.25 % at −0.38V. As a result of the above, pure and Mo-doped CuO photoelectrodes are low-cost thin films and have a high-efficiency performance for green hydrogen generation industrially. • Mo-doped CuO thin films were carefully sputtered on an ITO substrate at different temperatures. • Effect of doping and temperature on structural and optical properties of CuO thin films has been studied. • The efficiency of Mo-doped CuO photoelectrode at room temperature outperforms the rest. • Photocurrent density ∼2.25 mA/cm2 and (ABPE%) 4.25 % at −0.38V were revealed. • Mo–CuO photoelectrodes have a high level performance for green hydrogen generation. [ABSTRACT FROM AUTHOR]

The nonlinear absorption (NLA) properties of ITO thin films were performed by utilizing femtosecond (100 fs), a high-repetition rate (80 MHz), and near-infrared (NIR) (750–820 nm) laser pulses. A radio frequency (RF) magnetron sputtering system was used to prepare ITO thin films of two different thicknesses. A scanning electron microscope was used to determine the film thickness and a UV–Visible spectrophotometer was used to observe the linear optical properties of the thin films. The open aperture Z-scan technique's nonlinear absorption studies of ITO thin films exhibited a reverse saturable absorption. The NLA properties of the ITO films varied depending on ITO thickness, incident laser power, and excitation wavelength, attributed to the increasing localized defect states in the band gap. The results showed that increasing the excitation wavelength from 750 to 820 nm reduces the nonlinear absorption coefficient of the ITO thin films from 15.88 × 10−7 to 9.43 × 10−7 cm/W and from 6.72 × 10−7 to 5.15 × 10−7 cm/W at ITO thicknesses of 280 and 170 nm, respectively. In contrast to the film thickness, the nonlinear absorption coefficient was inversely proportional to the excitation laser wavelength. Additionally, the optical limiting of ITO thin films was investigated, and it was found that there is a clear correlation between optical limiting and thin film thickness. [ABSTRACT FROM AUTHOR]

In this work, cuprous oxide (Cu2O) thin films were prepared using a simplistic sputtering technique. The films were grown on both traditional fluorine-doped tin oxide (FTO) and Ti-metallic substrates. X-ray diffraction applied for investigation of the crystal structure proved that the Cu2O layer acquires the cubic structure with a (111) main peak at 2θ of 36.46°. The optical absorption and transmission were detected through the utilization of a UV-Vis spectrophotometer, and the optical bandgap for the Cu2O layer was determined to be ~2.15 eV using Tauc's equation. XPS and scanning electron microscopy were also performed for chemical structure and morphological investigation, respectively. The optoelectronic behaviors for the prepared samples were carried out using a Keithley source meter; the photocurrent density was measured in a range of applied voltage between −1 and 1 volt under the illumination of a xenon lamp with a power density of 100 mWcm−2. External quantum efficiency, sensitivity, responsivity, and detectivity were computed using proprietary models based on the experimental data. [ABSTRACT FROM AUTHOR]

Nanostructured pure and molybdenum (Mo)-doped nickel oxide (NiO) thin films with various concentrations of Mo dopants were successfully sputtered on indium-doped tin oxide (ITO) substrates to apply in the ultraviolet (UV) photodetector sensors. The influence of Mo concentration on the thin films' structural, morphological, and optical properties was studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray, and UV–Vis spectrophotometer. The XRD studies confirm that all the prepared films are polycrystalline and possess a cubic phase structure. The FE-SEM images suggest that the distribution of the prepared samples on the substrate is homogeneous and free from any cracks. Spectrophotometry studies reveal the decrement of the optical band gap with the increase of Mo concentration in NiO thin films. All thin-film current–voltage curves measured under dark conditions and UV illumination of 390 nm showed Ohmic contacts. A noticeable improvement in the responsivity and external quantum efficiency (EQE) with the increased Mo concentration was detected. The metal–semiconductor–metal (MSM) employed in NiO thin films showed maximum responsivity and EQE of 539 mA/W and 171.4% at 390 nm, respectively, for the sample with 1.73 at% Mo doping. [ABSTRACT FROM AUTHOR]

The modification and tailoring characteristics of nanostructured materials are of great interest due to controllable and unusual inherent properties in such materials. A simple spray pyrolysis technique was used to prepare pure and La-doped ZnO films. The influence of La concentration (0, 0.33, 0.45, 0.66, 0.92 and 1.04 at. %) on the structural, optical, and magnetic properties of ZnO was investigated. The exact nominal compositions of the prepared films were determined from the field emission scanning electron microscope occupied with EDX. X-ray diffraction confirmed that the samples possessed single-phase hexagonal wurtzite structure. The main crystal size was decreased from 315.50 Å to 229.04 Å depending on La dopant concentration. This decrease is due to the small ionic radius of Zn ions in compared to La ions. The band gap values were found to be depend strongly on La3+ ion content. Introducing La into ZnO induces a clear magnetic moment without any distortion in the geometrical symmetry, it also reveals the ferromagnetic coupling. The saturation magnetic moment of 1.04 at.% La-doped ZnO shows the highest value of 0.014 emu, which is ∼23 times higher than pure ZnO sample. The obtained results were discussed and compared with other literature data and showed an acceptable agreement. • Pure and La doped ZnO thin films were synthesized in hexagonal phase. • Band gap values depended strongly on the La doping ratio. • La doping induced ferromagnetism in the paramagnetic ZnO. [ABSTRACT FROM AUTHOR]

Pure and cobalt (Co) doped CuO thin films have been deposited by DC and AC reactive magnetron sputtering technique. The doping ratio has been controlled by the RF power of the AC sputtering unit. The sputtering power ranges from 0 to 50 W. The crystal structure of the films has been identified by X-ray diffraction. One of the peaks has been shifted toward the high diffraction angle. Energy dispersive analysis shows cationic deficiency of the pure and doped samples. Morphology of the films has been investigated by atomic force microscopy. Film roughness decrease with the increase of sputtering power. Spectrophotometry studies reveal that films darken with the increase of sputtering power. The current-voltage curves show Ohmic contacts and an enhancement in the conductivity with the increase of Co concentrations. Photoresponse measurements have shown that the film doped at 50 W is the best photodetector sensor. [ABSTRACT FROM AUTHOR]

Undoped and doped copper oxide (CuO) with silver (Ag) was prepared using the SILAR technique on the ITO substrate to generate green hydrogen from the water-splitting process. The (−111) and (111) were the most intense reflections of crystallographic planes observed in pure and Ag-doped CuO thin films. Ag doping within the crystal structure of pristine leads to increasing the crystallite size. FESEM images show homogeneity and uniform distribution for the pure and Ag-doped CuO thin films that confirm the particles have small sizes, give more features and are responsible for the target application. The doping process affected the energy band gap where it was 2.2 eV for the pure sample then descended to 1.9 eV as doping reached 5 % concentration of Ag element. The photoelectrochemical testing showed that the Ag 5 % content photoelectrode has a high value of photocurrent density approximately ∼ - 5 mA/cm2. [ABSTRACT FROM AUTHOR]

Hydrogen gas can be converted to electricity through fuel cells and is considered as a friendly energy source. Herein, pure Cu 2 O and Ni-doped Cu 2 O thin films were deposited on glass substrates using the RF/DC-sputtering technique for hydrogen production via the photoelectrochemical (PEC) water-splitting process. The preferred orientation for pure and Ni-doped Cu 2 O films was (111) crystallographic plane. The average nanograins size was decreased from 32.17 nm for pure to 10.40 nm through the doping process with Ni content. Field-emission scanning electron microscopy (FE-SEM) and ImageJ analysis showed that the pure Cu 2 O and Ni-doped Cu 2 O were composed of normal distribution of nanograins in a regular form. The optical bandgap of the Cu 2 O film was decreased from 2.35 eV to 1.9 eV after doping with 2.6 wt% of Ni-dopants. The photoluminescence (PL) spectra for all the sputtered films were recorded at room temperature to examine the effect of Ni-dopants in the Cu 2 O lattice. Pure and Ni-doped Cu 2 O films were applied for PEC water splitting for hydrogen (H 2) production under white light and monochromatic illumination. The PEC studies displayed that increasing the Ni content up to 2.6 wt% in the pure Cu 2 O films led to an increase in the photocurrent density to reach −5.72 mA/cm2. The optimum photoelectrode was studied for reproducibility, stability, and electrochemical impedance. The incident photon to current conversion efficiency (IPCE%) was 16.35% at 490 nm, and the applied bias photon to current conversion efficiency (ABPE%) was 0.90% at 0.65 V. Consequently, Ni-doped Cu 2 O photoelectrodes are efficient and low-cost for practical and industrial solar H 2 production. [Display omitted] • Well-compacted Ni-doped Cu 2 O photocatalysts were sputtered on glass substrates. • A granular structure was fabricated by doping the Cu 2 O films with Ni atoms. • Optical and structural properties of Cu 2 O were improved by adding Ni contents. • A J ph ∼5.72 mA/cm2 at 0.385 V vs. RHE and ABPE% ∼0.71% at 0 V vs. RHE were achieved. • Doping Cu 2 O with Ni atoms enhanced the overall PEC water splitting performance. [ABSTRACT FROM AUTHOR]