• Energy Research

This study describes the synthesis of delafossite, CuFeO2, as a primary photocatalytic material for hydrogen generation. A photoelectrode, CuFeO2/CuO/Cu, was prepared by combusting a Cu foil dipped in FeCl3 in ambient air. This photoelectrode showed excellent optical behavior for the hydrogen generation reaction from sewage water, producing 90 µmol/h of H2. The chemical structure was confirmed through XRD and XPS analyses, and the crystalline rhombohedral shape of CuFeO2 was confirmed using SEM and TEM analyses. With a bandgap of 1.35 ev, the prepared material displayed excellent optical properties. Electrochemical measurements for H2 gas generation were carried out using the CuFeO2/CuO/Cu photoelectrode, comparing the effect of light and dark and monochromatic wavelength light. The electrode exhibited significant enhancement in light compared to dark, with current density (Jph) values of −0.83 and −0.1 mA·cm−2, respectively. The monochromatic light also had a noticeable effect, with the Jph value increasing from −0.45 to −0.79 mA·cm−2 as the wavelength increased from 640 to 390 nm. This system is cheap and durable, making it a promising solution for hydrogen gas fuel generation in the industry.

AbstractTungsten oxide‐iodide/poly‐2‐aminobenzenethiol nanocomposite (WO2I2/P2ABT) is created through the introduction of iodine into polymer chains, where iodine serves as an oxidizing agent during the synthesis process. With a highly porous structure, the sensing capabilities of WO2I2/P2ABT for detecting Pb2+ ions are successfully demonstrated, revealing a Nernstian slope of 26.2 mV/decade. This detection is accomplished through a simple potentiometric technique, employing a simple two‐electrode cell setup. To further validate its performance, cyclic voltammetry is conducted using a three‐electrode system, revealing a remarkable sensitivity of 7.2 × 10−5 A M−1 for Pb2+ ions. The nanocomposite sensor's selectivity is rigorously examined by subjecting it to testing in the presence of 0.01 M interfering ions. The results unequivocally demonstrate that the sensor remains unresponsive to these interfering ions, underscoring its remarkable selectivity for Pb2+ ions. Moreover, the sensor's behavior is evaluated under real‐world conditions using natural samples, where, no indications of interference from other ions are observed. This is estimated by the absence of cyclic peaks in the voltammogram, indicating the sensor's unique ability to selectively detect Pb2+ ions without being perturbed by other ions that may be naturally occurring in the samples. These findings emphasize the nanocomposite sensor's potential for a wide array of applications in environmental monitoring and analytical chemistry. Its extraordinary combination of high sensitivity, impeccable selectivity, and robust performance in practical scenarios establishes it as an invaluable tool for detecting Pb2+ ions across various contexts.

AbstractA promising optoelectronic device for light sensing in both the UV and Vis regions is fabricated. This device consists of a nanocomposite resembling coral reefs, termed AgI/polypyrrole‐iodide (AgI/Ppy‐I). The resulting nanocomposite exhibits a hierarchical structure wherein larger particles, comprising smaller particles ~45 nm and an optical bandgap measuring 2.4 eV, form a coral reef‐like morphology. The sensitivity estimation of this constructed optoelectronic device relies on evaluating the current density (Jph) values. Under illumination, a remarkable augmentation in current density (Jph = 0.46 mA cm−2) with a promising value compared to the dark condition's 0.12 mA cm−2. The optical characteristics of this nanocomposite make it highly conducive to efficient UV–Vis light sensing. The values of D (detectivity), reflecting the device's sensitivity, are notably high at 4 × 108 and 3.82 × 108 Jones in the UV and Vis regions, correspondingly. The potential of this photodetector is reinforced by the computed R‐values, which denote the device's responsivity. With values of 1.8 and 1.72 mA W−1 across these two optical regions, correspondingly, it showcases the nanocomposite's effectiveness in transforming incident light into electrical current. Moreover, the appeal of this photodetector extends beyond its performance characteristics. Its cost‐effectiveness, eco‐friendliness, straightforward preparation methodology, scalability for mass production, and high stability collectively. The versatility of this material, coupled with its advantageous attributes, opens avenues for its widespread application, catering to the diverse needs of industries and contributing to the accessibility of efficient optoelectronic devices for a broader audience.

AbstractThis research introduces a novel technique for transforming wastewater into renewable hydrogen gas using an innovative photoelectrode composed of CrO3‐Cr2O3/polypyrrole (Ppy), synthesized through a one‐pot method. The photoelectrode is applied to split wastewater under different light conditions: darkness, white light, and monochromatic light. In the absence of light, the CrO3‐Cr2O3/Ppy photoelectrode produces a photocurrent density (Jph) value of 0.54 mA cm−2, which significantly increases to 0.78 mA cm−2 under white light exposure. The Jph values range from 0.68 to 0.76 mA cm−2 at wavelengths between 730 and 340 nm, showcasing the photoelectrode's remarkable sensitivity. This sensitivity highlights the potential of the photoelectrode to efficiently capture light energy for applications in wastewater treatment and green hydrogen production. By utilizing wastewater as a renewable energy source and employing the CrO3‐Cr2O3/Ppy photoelectrode, this approach addresses environmental concerns and energy needs concurrently. The proposed prototype for a three‐electrode cell aims to directly produce hydrogen gas from wastewater, with the ultimate goal of generating hydrogen suitable for industrial applications. This innovative solution not only addresses wastewater treatment but also transforms it into a valuable source of green energy, emphasizing the potential for positive environmental and energy‐related advancements.

Three nanomaterials based on polyaniline (PANI) are prepared on indium tin oxide (ITO) and applied as electrodes for H2 generation due to the water‐splitting process. PANI/ITO films are prepared using oxidation polymerization method at 25°C, then coated with Au nanoparticles with different thicknesses (sputter time from 1 to 2 min). The three prepared electrodes; PANI/ITO (Electrode (0), 1‐min‐Au/PANI/ITO (Electrode (I)), and 2‐min‐Au/PANI/ITO (Electrode (II)) are compared for H2 generation from H2O. Scanning electron microscope, X‐ray diffraction, UV‐Vis spectrophotometer, and Fourier‐transform infrared spectroscopy analyses have been carried out, in which the average PANI crystal size was ~20 nm. Moreover, the bandgaps were determined, in which 2‐min‐Au/PANI/ITO has the optimum bandgap of 2.25 eV. The characteristic behavior of the H2 generation took place depending on the current density (Jph) value by using Jph–V and Jph–time study. Also, the incident photon‐to‐current conversion efficiency (IPCE) and the applied bias photon‐to‐current efficiency (ABPE) were calculated for the Electrode (II) at 25°C. The optimum IPCE and ABPE efficiency were 18.7 and 0.99%, respectively, at 390 nm. By increasing the temperature to 70°C, the IPCE efficiency increases to about 37%. Finally, activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*) were determined, in which the values were 24.32 kJ mol−1, 10.90 kJ mol−1, and 74.99 J K−1 mol−1, respectively. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

This study highlights the utilization of the Cr2S3-Cr2O3/P2ABT nanocomposite photoelectrode for efficient and highly sensitive photon absorption, enabling the generation of green hydrogen through the production of hot electrons upon illumination. The nanocomposite is synthesized via a one-pot reaction using K2Cr2O7 and 2-aminobenzene-1-thiol monomer, and the presence of Cr2S3-Cr2O3 is confirmed by XRD and XPS analysis within the composite. The optical properties of the Cr2S3-Cr2O3/poly-2-aminobenzene-1-thiol composite exhibit wide spectral coverage from UV to IR, with a bandgap of 1.6 eV. The diverse morphological behavior observed in the composite correlates with its optical properties, with the cleft spherical particles of the pure polymer transforming into rod-like structures embedded within the polymer matrix. The generated hydrogen gas demonstrates an impressive efficiency of 40.5 mole/10.cm2.h through electrochemical testing. The current density (Jph) values are evaluated under different light frequencies using optical filters ranging from 730 to 340 nm, resulting in Jph values of 0.012 and 0.014 mA.cm−2, respectively. These findings present a promising avenue as green hydrogen for industrial applications, leveraging the potential of the Cr2S3-Cr2O3/P2ABT nanocomposite photoelectrode.