Surface Potential/Wettability and Interface Charge Transfer Engineering of Copper-Oxide (Cu–MOx, M = W, Ti, and Ce) Hybrids for Efficient Wastewater Treatment through Adsorption–Photocatalysis Synergy

Preparation of polyethyleneimine modified cellulose/nano-CdS composite aerogel and its photocatalytic properties for organic dyes under visible light

Organic dyes are extensively used in industries such as textiles and printing, contributing to the increasing discharge of wastewater and posing significant risks to human health. Conventional photocatalysts, including metal oxides and sulfides, often exhibit limited pollutant adsorption capacities and suffer from charge carrier recombination. In this study, we synthesized a novel composite aerogel via the lyophilization of cellulose modified with polyethyleneimine and cadmium sulfide. This composite demonstrated exceptional efficacy in degrading of methyl orange (MO) and methylene blue (MB). The composite exhibits a unique three-dimensional structure characterized by a multitude of uneven pores, providing abundant active sites favorable for catalytic reactions. Furthermore, the material shows significant light absorption within the visible spectrum and has a low band gap. Under optimized conditions, the removal efficiencies of MO and MB reached 99.56 % and 100 %, respectively. After five consecutive cycles, the degradation rates of MO and MB remained high at 83 % and 87 %, respectively, showcasing excellent photocatalytic activity and stability. The amino and hydroxyl groups within the composite act as electron donors during photocatalytic reactions, with reaction kinetics following a quasi-first-order model. The mechanism of dye removal by the composite involves a synergistic interplay between adsorption and photocatalytic reduction, underscoring its potential for efficient wastewater treatment.

High-Performance Electro-optical Dual-Mode Color-Changing and Energy Storage Device Based on Mo-Doped WO3 and TiO2/NiO Thin Films

Under optical and electrical control, a multifunctional electro-optical dual-control color-changing and energy storage device not only realizes fast color conversion but also achieves good energy storage performance. In this work, Mo-doped WO3 (Mo-WO3) films were prepared by a one-step hydrothermal method, among which the 2 at. % Mo-doped WO3 film has the best electrochromic and energy storage performance. Meanwhile, TiO2/NiO composite films were prepared by the hydrothermal method and electrodeposition method. The TiO2/NiO/N719 photoanode was prepared by the dip-dyeing method on the TiO2/NiO composite film. The results show that the TiO2/NiO-10s/N719 composite film has excellent photoelectric conversion and energy storage properties. Finally, choosing Mo-WO3 as the cathode and the TiO2/NiO/N719 film as the anode, a multifunctional electro-optical dual-control Mo-WO3@TiO2/NiO/N719 color-changing and energy storage device was constructed. Under electrical control, it shows a fast color switching rate (the coloring/bleaching time is 4.1/2.9 s), excellent coloration efficiency (62.1 cm2/C), obviously improved area capacitance (90.4 mF/cm2), and excellent cycle stability. Under optical control, it shows a shortened optical response time (the coloring/bleaching is 70.3/158.9 s), excellent coloration efficiency (58.2 cm2/C), better area capacitance (51.1 mF/cm2), and excellent photoelectric conversion efficiency.

Research progress in the degradation of printing and dyeing wastewater using chitosan based composite photocatalytic materials

The surge in economic growth has spurred the expansion of the textile industry, resulting in a continuous rise in the discharge of printing and dyeing wastewater. In contrast, the photocatalytic method harnesses light energy to degrade pollutants, boasting low energy consumption and high efficiency. Nevertheless, traditional photocatalysts suffer from limited light responsiveness, inadequate adsorption capabilities, susceptibility to agglomeration, and hydrophilicity, thereby curtailing their practical utility. Consequently, integrating appropriate carriers with traditional photocatalysts becomes imperative. The combination of chitosan and semiconductor materials stands out by reducing band gap energy, augmenting reactive sites, mitigating carrier recombination, bolstering structural stability, and notably advancing the photocatalytic degradation of printing and dyeing wastewater. This study embarks on an exploration by initially elucidating the technical principles, merits, and demerits of prevailing printing and dyeing wastewater treatment methodologies, with a focal emphasis on the photocatalytic approach. It delineates the constraints encountered by traditional photocatalysts in practical scenarios. Subsequently, it comprehensively encapsulates the research advancements and elucidates the reaction mechanisms underlying chitosan based composite materials employed in treating printing and dyeing wastewater. Finally, this work casts a forward-looking perspective on the future research trajectory of chitosan based photocatalysts, particularly in the realm of industrial applications.

High specific surface CeO2-NPs doped loose porous C3N4for enhanced photocatalytic oxidation ability

Porous C₃N₄(PCN) is favored by researchers because it has more surface active sites, higher specific surface area and stronger light absorption ability than traditional g-C₃N₄. In this study, cerium dioxide nanoparticles (CeO₂-NPs) with mixed valence state of Ce³⁺and Ce⁴⁺were doped into the PCN framework by a two-step method. The results indicate that CeO₂-NPs are highly dispersed in the PCN framework, which leads to a narrower band gap, a wider range of the light response and an improved the separation efficiency of photogenerated charge in PCN. Moreover, the specific surface area (145.69 m²g^-1) of CeO₂-NPs doped PCN is a 25.5% enhancement than that of PCN (116.13 m²g^-1). In the experiment of photocatalytic selective oxidation of benzyl alcohol, CeO₂-NPs doped porous C₃N₄exhibits excellent photocatalytic activity, especially Ce-PCN-30. The conversion rate of benzyl alcohol reaches 74.9% using Ce-PCN-30 as photocatalyst by 8 h of illumination, which is 25.7% higher than that of pure porous C₃N₄. Additionally, CeO₂-NPs doped porous C₃N₄also exhibits better photocatalytic efficiency for other aromatic alcohols.

Metallic Copper-Containing Composite Photocatalysts: Fundamental, Materials Design, and Photoredox Applications

Semiconductor photocatalysis has long been regarded as a potential solution to tackle the energy and environmental challenges since the first discovery of water splitting by TiO₂ almost 50 years ago. The past few years have seen a tremendous flurry of research interest in the modification of semiconductors because of their shortcomings in the aspects of solar harvesting, electron-hole pairs separation, and utilization of photogenerated carriers. Among the various strategies, the introduction of metallic copper into the photocatalysis system can not only enhance the absorption of sunlight and the separation efficiency of photogenerated electrons and holes, but also increase the adsorption ability of substrate and the number of active sites, so as to realize the high solar to chemical energy conversion efficiency. This review focuses on the rational design of copper-based composites and their applications in photoredox catalysis. First, the preparation methods of metallic copper-containing composites are discussed. Then, the applications of different types of copper-based composites in the photocatalytic removal of pollutants, splitting of water to hydrogen production, reduction of carbon dioxide, and conversion of organic matter are introduced. Finally, the opportunities and challenges in the design and synthesis of copper-based composites and their applications in the photocatalysis are prospected.