Fabrication of rGO-bridged TiO2/g-C3N4 Z-scheme Nanocomposites via Pulsed Laser Ablation for Efficient Photocatalytic CO2 Reduction.

Highly efficient photocatalysts can be fabricated using favorable charge transfer nanocomposite channel structures. This study adopted pulsed laser ablation in liquid (PLAL) to obtain rGO-bridged TiO2/g-C3N4 (rGO-TiO2/g-C3N4) photocatalytic Z-scheme without the need for noble metals. In addition to evaluating the resulting nanocomposite's (comprising rGO nanosheets, TiO2 nanotubes, and g-C3N4 nanosheets) CO2 reduction effectiveness, its chemical, morphological, structural, and optical characteristics were examined using various analytical techniques. The findings revealed a synergistic interaction between g-C3N4 and TiO2, suggesting the presence of unique interfacial bonding, as well as enhanced visible light absorption. Notably, the ternary rGO-TiO2/g-C3N4 Z-scheme exhibits an excellent photocatalytic performance by photocatalytically converting CO2 into CO and CH4, with 81% selectivity towards the CO and 1.91% apparent quantum efficiency at 420 nm. Thus, the findings can pave the way for various Z-scheme systems in wide photocatalytic applications.

Photocatalytic Synthesis of Coumarin Derivatives Using Visible-Light-Responsive Strawberry Dye-Sensitized Titanium Dioxide Nanoparticles.

This study presents a novel method for the photocatalytic synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones (a coumarin derivative) using strawberry dye-sensitized TiO2 (SD-TiO2) under visible light. The synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones was achieved through a three-component, one-pot condensation reaction involving 3-acetyl coumarin, aldehydes, and urea, utilizing SD-TiO2 as a reusable and innovative photocatalyst at room temperature. The resulting SD-TiO2 photocatalyst was thoroughly characterized using FT-IR, XPS, XRD, SEM, and BET. The efficacy of SD-TiO2 was evaluated by comparing it to pristine TiO2 in terms of photocatalytic activity, and the optimal conditions for the synthesis process were determined. Notably, the SD-TiO2 photocatalyst exhibited a maximum yield of the compound, reaching up to 96% in just 30 min with a catalyst concentration of 1 mg/mL. This yield surpasses traditional thermal procedures employing reflux conditions, where 1 mg/mL of SD-TiO2 is sufficient to complete the reaction. The resulting 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones were further characterized using 1H-NMR and 13C-NMR. Moreover, the stability of the SD-TiO2 photocatalyst was confirmed through recyclability experiments and spectroscopic characterization, demonstrating its practicality for up to three consecutive reaction cycles.

Scalable Synthesis of Oxygen Vacancy-Rich Unsupported Iron Oxide for Efficient Thermocatalytic Conversion of Methane to Hydrogen and Carbon Nanomaterials.

Thermocatalytic methane decomposition (TCMD) involving metal oxides is a more environmentally friendly and cost-effective strategy for scalable hydrogen fuel production compared to traditional methane steam reforming (MSR), as it requires less energy and produces fewer CO/CO2 emissions. However, the unsupported metal oxide catalysts (such as α-Fe2O3) that would be suited for this purpose exhibit poor performance in TCMD. To overcome this issue, a novel strategy was developed as a part of this work, whereby oxygen vacancies (OVs) were introduced into unsupported α-Fe2O3 nanoparticles (NPs). Systematic characterization of the obtained materials through analytical techniques demonstrated that mesoporous nanostructured unsupported α-Fe2O3 with abundant oxygen vacancies (OV-rich α-Fe2O3 NPs) could be obtained by direct thermal decomposition of ferric nitrate at different calcination temperatures (500, 700, 900, and 1100 °C) under ambient conditions. The thermocatalytic activity of the resulting OV-rich α-Fe2O3 NPs was assessed by evaluating the methane conversion, hydrogen formation rate, and amount of carbon deposited. The TCMD results revealed that 900 °C was the most optimal calcination temperature, as it led to the highest methane conversion (22.5%) and hydrogen formation rate (47.0 × 10-5 mol H2 g-1 min-1) after 480 min. This outstanding thermocatalytic performance of OV-rich α-Fe2O3 NPs is attributed to the presence of abundant OVs on their surfaces, thus providing effective active sites for methane decomposition. Moreover, the proposed strategy can be cost-effectively scaled up for industrial applications, whereby unsupported metal oxide NPs can be employed for energy-efficient thermocatalytic CH4 decomposition into hydrogen fuel and carbon nanomaterials.

Solar-Driven Thermocatalytic Synthesis of Octahydroquinazolinone Using Novel Polyvinylchloride (PVC)-Supported Aluminum Oxide (Al2O3) Catalysts.

The chemical industry is one of the main fossil fuel consumers, so its reliance on sustainable and renewable resources such as wind and solar energy should be increased to protect the environment. Accordingly, solar-driven thermocatalytic synthesis of octahydroquinazolinone using polyvinylchloride (PVC)-supported aluminum oxide (Al2O3) as a catalyst under natural sunlight is proposed in this work. The Al2O3/PVC catalysts were characterized by FT-IR, SEM, BET, XRD, and XPS techniques. The obtained results indicate that the yield and reaction time can be modified by adjusting the molar ratio of the catalyst. To investigate the stability of the catalyst, the spent catalyst was reused in several reactions. The results indicated that, when a 50% Al2O3 catalyst is employed in an absolute solar heat, it performs exceptionally well in terms of yield (98%) and reaction time (35 min). Furthermore, the reaction times and yield of octahydroquinazolinone derivatives with an aryl moiety were superior to those of heteroaryl. All the synthesized compounds were well characterized by FT-IR, 1H-NMR, and 13C-NMR. The current work introduces a new strategy to use solar heat for energy-efficient chemical reactions using a cost-effective, recyclable environmentally friendly PVC/Al2O3 catalyst that produces a high yield.

Enhanced Structural, Optical Properties and Antibacterial Activity of PEO/CMC Doped TiO2 NPs for Food Packaging Applications.

In this article, the synthesis, optical, and electrical properties of composites consisting of polyethylene oxide (PEO), carboxymethyl cellulose (CMC), and titanium dioxide nanoparticles are examined. Flexible nanocomposite samples comprising PEO, CMC, and TiO2 nanoparticles were produced swiftly via using the cast synthesis method. In addition, XRD and FT-IR analysis were performed in order to analyze the structures of the prepared samples. Our results demonstrate the PEO/CMC blend's effectiveness in interacting with TiO2 nanoparticles. The optical properties of the PEO/CMC and nanocomposite samples, such as the energy band gap, were studied using the UV/Vis optical absorbance. It was found that as TiO2 NP weight fraction increases, the energy gap narrows. Moreover, TiO2 nanoparticles with an average size of 16 nm were formed in spherical and rod shapes, according to a TEM image. The SEM images demonstrate how the distribution of TiO2 NPs increased upon the surfaces of the prepared films. The antibacterial activity in the nanocomposites was shown to be enhanced by the TiO2 NP concentrations. Finally, we proposed that PEO/CMC-0.8 wt. % TiO2 nanocomposites with enhanced optical, electrical, and dielectric properties should be used in electrochemical devices.

In-situ sunlight-driven tuning of photo-induced electron-hole generation and separation rates in bismuth oxychlorobromide for highly efficient water decontamination under visible light irradiation.

Photocatalytic materials have received great interest due to their capability for remediating environmental pollution especially water pollution. However, the scalable application of the current photocatalytic materials is still limited by their poor visible-light absorption and low separation efficiency of charge carriers. Here, we report in-situ sunlight-driven tuning of photo-induced electron-hole generation and separation rates in bismuth oxychlorobromide (BiOCl0.8Br0.2) nanoflowers. It shows photochromic response under 10-minute natural sunlight irradiation changing color from white to black. The characterization reveals the presence of hydroxyl groups on the surface of the pristine BiOCl0.8Br0.2 nanoflowers and abundant oxygen vacancies for the sunlight-irradiated BiOCl0.8Br0.2 nanoflowers which narrow the bandgap and serve as electron trapping centers, thus effectively enhancing the generation and separation rates of electron-hole pairs. As a result, the sunlight-irradiated BiOCl0.8Br0.2 film demonstrates outstanding photocatalytic performance in water purification such as degrading Rhodamine B (RhB) dye under visible light irradiation with 2-fold higher than its pristine state.

Visible Light-Driven Photoelectrocatalytic Water Splitting Using Z-Scheme Ag-Decorated MoS2/RGO/NiWO4 Heterostructure.

Herein, we have successfully constructed a solid-state Z-scheme photosystem with enhanced light absorption capacity by combining the optoelectrical properties of AgNPs with those of the MoS2/RGO/NiWO4 (Ag-MRGON) heterostructure. The Ag-MRGON Z-scheme system demonstrates improved photo-electrochemical (PEC) water-splitting performance in terms of applied bias photon-to-current conversion efficiency (ABPE), which is 0.52%, and 17.3- and 4.3-times better than those of pristine MoS2 and MoS2/NiWO4 photoanodes, respectively. The application of AgNPs as an optical property enhancer and RGO as an electron mediator improved the photocurrent density of Ag-MRGON to 3.5 mA/cm2 and suppressed the charge recombination to attain the photostability of ∼2 h. Moreover, the photocurrent onset potential of the Ag-MRGON heterojunction (i.e., 0.61 VRHE) is cathodically shifted compared to those of NiWO4 (0.83 VRHE), MoS2 (0.80 VRHE), and MoS2/NiWO4 heterojunction (0.73 VRHE). The improved PEC water-splitting performance in terms of ABPE, photocurrent density, and onset potential is attributed to the facilitated charge transfer through the RGO mediator, the plasmonic effect of AgNPs, and the proper energy band alignments with the thermodynamic potentials of hydrogen and oxygen evolution.

Thermally Sensitized Membranes for Crude Oil-Water Remediation under Visible Light.

Effective remediation of produced water requires separating crude oil-water mixture and removing the dissolved organic pollutants. Membranes with selective wettability for water over oil enable the gravity-driven separation of an oil-water mixture by allowing water to permeate through while repelling oil. However, these membranes are often limited by their inability to remove the dissolved organic pollutants. In this work, a membrane with in-air superhydrophilic and underwater superoleophobic wettability is fabricated by thermal annealing of a stainless steel mesh. The resulting membrane possesses a hierarchical surface texture covered with a photocatalytic oxide layer composed of iron oxide and chromium oxide. The membrane exhibits chemical and mechanical robustness, which makes it suitable for remediation of crude oil and water mixture. Further, after being fouled by crude oil, the membrane can recover its inherent water-rich permeate flux upon visible light irradiation. Finally, the membrane demonstrates that it can separate surfactant-stabilized crude oil-in-water emulsion under gravity and decontaminate water-rich permeate by photocatalytic degradation of dissolved organic pollutants upon continuous irradiation of visible light.

Photofabrication of Highly Transparent Platinum Counter Electrodes at Ambient Temperature for Bifacial Dye Sensitized Solar Cells.

Platinum (Pt) counter electrodes (CEs) have consistently shown excellent electrocatalytic performance and holds the record of the highest power conversion efficiency (PCE) for dye-sensitized solar cells (DSSCs). However, its use for large-scale production is limited either by high temperature required for thermal decomposition of its precursor or by wastage of the material leading to high cost or sophisticated equipment. Here, we report a novel photofabrication technique to fabricate highly transparent platinum counter electrodes by ultraviolet (UV) irradiation of platinic acid (H2PtCl6.6H2O) on rigid fluorine-doped tin oxide (FTO) and flexible indium-doped tin oxide (ITO) on polyethylene terephthalate (PET) substrates. The photofabrication technique is a facile and versatile method for the fabrication of Pt CEs for dye sensitized solar cells (DSSCs). The photofabricated Pt CEs were used to fabricate bifacial DSSCs with power conversion efficiencies (PCEs) attaining 7.29% for front illumination and 5.85% for rear illumination. The highest percentage ratio of the rear illumination efficiency to the front illumination efficiency (ηR) of 85.92% was recorded while the least ηR is 77.91%.

Fabrication of Water Jet Resistant and Thermally Stable Superhydrophobic Surfaces by Spray Coating of Candle Soot Dispersion.

A facile synthesis method for highly stable carbon nanoparticle (CNP) dispersion in acetone by incomplete combustion of paraffin candle flame is presented. The synthesized CNP dispersion is the mixture of graphitic and amorphous carbon nanoparticles of the size range of 20-50 nm and manifested the mesoporosity with an average pore size of 7 nm and a BET surface area of 366 m2g-1. As an application of this material, the carbon nanoparticle dispersion was spray coated (spray-based coating) on a glass surface to fabricate superhydrophobic (water contact angle > 150° and sliding angle < 10 °) surfaces. The spray coated surfaces were found to exhibit much improved water jet resistance and thermal stability up to 400 °C compared to the surfaces fabricated from direct candle flame soot deposition (candle-based coating). This study proved that water jet resistant and thermally stable superhydrophobic surfaces can be easily fabricated by simple spray coating of CNP dispersion gathered from incomplete combustion of paraffin candle flame and this technique can be used for different applications with the potential for the large scale fabrication.

Fabrication and Wettability Study of WO3 Coated Photocatalytic Membrane for Oil-Water Separation: A Comparative Study with ZnO Coated Membrane.

Superhydrophilic and underwater superoleophobic surfaces were fabricated by facile spray coating of nanostructured WO3 on stainless steel meshes and compared its performance in oil-water separation with ZnO coated meshes. The gravity driven oil-water separation system was designed using these surfaces as the separation media and it was noticed that WO3 coated stainless steel mesh showed high separation efficiency (99%), with pore size as high as 150 µm, whereas ZnO coated surfaces failed in the process of oil-water separation when the pore exceeded 50 µm size. Since, nanostructured WO3 is a well known catalyst, the simultaneous photocatalytic degradation of organic pollutants present in the separated water from the oil water separation process were tested using WO3 coated surfaces under UV radiation and the efficiency of this degradation was found to be quite significant. These results assure that with little improvisation on the oil water separation system, these surfaces can be made multifunctional to work simultaneously for oil-water separation and demineralization of organic pollutants from the separated water. Fabrication of the separating surface, their morphological characteristics, wettability, oil water separation efficiency and photo-catalytic degradation efficiency are enunciated.

A Rapid and Cost-Effective Laser Based Synthesis of High Purity Cadmium Selenide Quantum Dots.

A rapid and cost effective method is developed to synthesize high purity cadmium Selenide (CdSe) quantum dots in acetone medium using second harmonic of Nd:YAG nanosecond pulsed laser of 532 nm wavelength. The thermal agglomeration due the nanosecond pulse duration of the laser was successfully eliminated by using unfocussed laser beam and thereby providing a favorable conditions for the synthesis of quantum dots having the grain size of 3 nm. The morphological and optical characterizations like XRD, HRTEM, optical absorption of the synthesized CdSe quantum dots, reveal that the material possesses the similar characteristics of the one synthesized through cumbersome wet chemical methods. Relative to the CdSe bulk material, the synthesized CdSe quantum dots showed a blue shift in the measured band gap energy from near infrared spectral region to visible region, making this material very attractive for many solar energy harvesting applications like photo-catalysis and solar cells.

Synthesis of Cu/Cu2O nanoparticles by laser ablation in deionized water and their annealing transformation into CuO nanoparticles.

Nano-structured Cupric Oxide (CuO) has been synthesized using pulsed laser ablation of pure copper in water using Q-switched pulsed laser beam of 532 nm wavelength and, 5 nanosecond pulse duration and laser pulse energy of 100 mJ/pulse. In the initial unannealed colloidal suspension, the nanoparticles of Copper (Cu) and Cuprious oxide (Cu2O) were identified. Further the suspension was dried and annealed at different temperatures and we noticed the product (Cu/Cu2O) was converted predominantly into CuO at annealing temperature of 300 degrees C for 3 hours. As the annealing temperature was raised from 300 to 900 degrees C, the grain sizes of CuO reduced to the range of 9 to 26 nm. The structure and the morphology of the prepared samples were investigated using X-ray diffraction and Transmission Electron Microscope. Photoluminescence and UV absorption spectrometry studies revealed that the band gap and other optical properties of nano-structured CuO were changed due to post annealing. Fourier transform spectrometry also confirmed the transformation of Cu/Cu2O into CuO.