Au nanoparticles decorated polypyrrole-carbon black/g-C3N4 nanocomposite as ultrafast and efficient visible light photocatalyst

Construction of Au quantum dots/nitrogen-defect-enriched graphite carbon nitride heterostructure via photo-deposition towards enhanced nitric oxide photooxidation

The challenge of mitigating pollution stemming from industrial exhaust emissions is a pressing issue in both academia and industry. This study presents the successful synthesis of nitrogen-defect-enriched graphite carbon nitride (g-C3N4) using a two-step calcination technique. Furthermore, a g-C3N4-Au heterostructure was fabricated through the photo-deposited Au quantum dots (QDs). When subjected to visible light irradiation, this heterostructure exhibited robust nitric oxide (NO) photooxidation activity and stability. With its fluffy, porous structure and large surface area, the nitrogen-defect-enriched g-C3N4 provides more active sites for photooxidation processes. The ability of g-C3N4 to absorb visible light is enhanced by the local surface plasmon resonance (LSPR) effect of Au QDs. Additionally, the lifetime of photogenerated charge carriers is extended by the presence of N defects and Au, which effectively prevent photogenerated electron-hole pairs from recombining during the photooxidation process. Moreover, the oxidation pathway of NO was analyzed through In-situ Fourier transform infrared (FT-IR) spectroscopy and Density Functional Theory (DFT) calculation. Computational findings revealed that the introduction of Au QDs decreases the activation energy of the oxidation reaction, thereby facilitating its occurrence while diminishing the formation of intermediate products. As a result, NO is predominantly converted to nitrate (NO3-). This work unveils a novel approach to constructing semiconductor-cocatalyst heterostructures and elucidates their role in NO photooxidation.

A Sensitive Hydroquinone Amperometric Sensor Based on a Novel Palladium Nanoparticle/Porous Silicon/Polypyrrole-Carbon Black Nanocomposite

Exposure to hydroquinone (HQ) can cause various health hazards and negative impacts on the environment. Therefore, we developed an efficient electrochemical sensor to detect and quantify HQ based on palladium nanoparticles deposited in a porous silicon-polypyrrole-carbon black nanocomposite (Pd@PSi-PPy-C)-fabricated glassy carbon electrode. The structural and morphological characteristics of the newly fabricated Pd@PSi-PPy-C nanocomposite were investigated utilizing FESEM, TEM, EDS, XPS, XRD, and FTIR spectroscopy. The exceptionally higher sensitivity of 3.0156 μAμM^-1 cm^-2 and a low limit of detection (LOD) of 0.074 μM were achieved for this innovative electrochemical HQ sensor. Applying this novel modified electrode, we could detect wide-ranging HQ (1-450 μM) in neutral pH media. This newly fabricated HQ sensor showed satisfactory outcomes during the real sample investigations. During the analytical investigation, the Pd@PSi-PPy-C/GCE sensor demonstrated excellent reproducibility, repeatability, and stability. Hence, this work can be an effective method in developing a sensitive electrochemical sensor to detect harmful phenol derivatives for the green environment.

Facile Synthesis of Poly(o-anisidine)/Graphitic Carbon Nitride/Zinc Oxide Composite for Photo-Catalytic Degradation of Congo Red Dye

Growing industry and its effluents create a serious environmental concern. Various industrial wastes such as toxic dyes and volatile organic compounds are posing a threat to a clean environment because of their non-biodegradable nature and high chemical stability. In recent years, the degradation of toxic dyes and drugs by photo-catalysts has gained much importance and proved a successful approach to capture light by hybrid photo-catalysts for decomposing toxic organic molecules. This work presents the synthesis of a poly(o-anisidine)-based composite with graphitic carbon nitride and zinc oxide (POA/g-C3N4/ZnO) and its utilization as a photo-catalyst. Various analytical techniques investigated the synthesized photo-catalysts’ chemical structure, crystallinity, and morphology. The degradation of Congo red dye evaluated the efficiency of the photo-catalyst in an aqueous medium under ultraviolet light. It was revealed that the photo-catalytic activity of the synthesized POA/g-C3N4/ZnO composites show 81.43%, 92.28%, and 87.05% degradation. This sustainable composite will be highly beneficial to treat industrial wastewater to make our environment clean.

A Review on Pulsed Laser Preparation of Nanocomposites in Liquids and Their Applications in Photocatalysis

The purpose of photocatalysis is to realize the conversion between solar energy and chemical energy, and it is essential to develop a high-performance photocatalyst under visible-light irradiation. The conventional methods for photocatalyst preparation are mainly wet chemical routes, and abundant yields can be obtained. However, the products are not neat and accompanied by chemical groups and impurities, which are not beneficial for the enhancement of photocatalytic performance. In recent years, as a powerful tool for nanomaterial fabrication, pulsed laser heating in a liquid medium has been utilized to prepare a variety of nanocomposites. Products with synergistic effects and high crystallinity can be rapidly prepared under pulsed laser selective heating, which is beneficial for obtaining more effective photocatalytic performance. In this review, the typical characteristics of pulsed laser heating in liquids and their prepared nanocomposites for photocatalytic applications are summarized. This review not only highlights the innovative works of pulsed-laser-prepared nanocomposites in liquids for photocatalysis but also briefly introduces the specific challenges and prospects of this field.

Benzoquinone-Pyrrole Polymers as Cost-Effective Cathodes toward Practical Organic Batteries

Organic cathode materials (OCMs) for rechargeable Li and Na batteries show great advantages in resource sustainability and huge potential in electrochemical performance but suffer from dissolution problems and costly synthesis. Herein, for the first time, we investigated the copolymer of benzoquinone (BQ) and pyrrole (Py), namely, poly(benzoquinone-pyrrole) (PBQPy), as an OCM for Li batteries. The low-cost raw materials and solvent-free synthesis provide PBQPy much brighter prospects in large-scale production compared to other carbonyl-based polymer cathode materials. Nevertheless, PBQPy showed one of the best electrochemical performances among all OCMs, including excellent energy density (2.32 V × 255 mAh g^-1 = 592 Wh kg^-1), rate capability (79%@2000 mA g^-1), and cycling stability (81%@1000th cycle). By introducing poly(benzoquinone-methyl pyrrole) for comparison, as well as employing density functional theory calculations and various characterizations for in-depth understanding, the synthesis mechanism, polymer structure, electrochemical behavior, and redox mechanism were clearly clarified. It is believed that this work will encourage more efforts to develop cost-effective OCMs toward practical organic batteries.

Enhanced carriers separation in novel in-plane amorphous carbon/g-C3N4 nanosheets for photocatalytic environment remediation

Although carbon-based materials/g-C₃N₄ heterostructure with an up-down structure in space can inhibit the recombination of charge carriers, the electron transfer is still suppressed by the interlayer van der Waals force. Herein, amorphous carbon is successfully introduced into the g-C₃N₄ nanosheet (CNS) by a self-conversion process to form an in-plane heterostructure of amorphous carbon/g-C₃N₄ (CNSC₁). Kelvin probe atomic force microscopy (KPFM) and density functional theory (DFT) confirm that g-C₃N₄ and amorphous carbon are in the same plane, which can generate the surface electric field of CNSC₁, providing a driving force for the transfer of electrons from g-C₃N₄ to amorphous carbon. Meanwhile, the sp²-hybridized π conjugation bond of amorphous carbon can rapidly capture and store photogenerated electrons, inhibiting charge carrier recombination and thus generating more electrons to facilitate the yield of hydroxyl radicals. The photocatalytic activity of CNSC₁ for the degradation of tetracycline and rhodamine B is 2.7 times and 4.8 times higher than that of CNS, respectively, due to the efficient interface charge separation. This work is expected to provide a new idea for the combination of carbon materials and g-C₃N₄.