Solvothermal synthesis and enhanced photocatalytic hydrogen production of Bi/Bi2MoO6 co-sensitized TiO2 nanotube arrays

Photocatalytic Enhancement Strategy with the Introduction of Metallic Bi: A Review on Bi/Semiconductor Photocatalysts

Semiconductor photocatalysis has great potential in the fields of solar fuel production and environmental remediation. Nevertheless, the photocatalytic efficiency still constrains its practical production applications. The development of new semiconductor materials is essential to enhance the solar energy conversion efficiency of photocatalytic systems. Recently, the research on enhancing the photocatalytic performance of semiconductors by introducing bismuth (Bi) has attracted widespread attention. In this review, we briefly overview the main synthesis methods of Bi/semiconductor photocatalysts and summarize the control of the micromorphology of Bi in Bi/semiconductors and the key role of Bi in the catalytic system. In addition, the promising applications of Bi/semiconductors in photocatalysis, such as pollutant degradation, sterilization, water separation, CO2 reduction, and N2 fixation, are outlined. Finally, an outlook on the challenges and future research directions of Bi/semiconductor photocatalysts is given. We aim to offer guidance for the rational design and synthesis of high-efficiency Bi/semiconductor photocatalysts for energy and environmental applications.

Pt-Cu@Bi2MoO6/TiO2 Photocatalyst for CO2 Reduction

Bi2MoO6/TiO2 heterojunction photocatalysts were constructed by depositing Bi2MoO6 nanosheets on TiO2 nanobelts' surface using a solvothermal method, and the surface of the optimum Bi2MoO6/TiO2 composite was decorated with copper and/or platinum nanoparticles. The synthesized samples were investigated for the CO2 photocatalytic reduction. The structural and optical properties of synthesized photocatalysts were characterized by XRD, FESEM, EDX, N2-physisorption, Raman, TPD-CO2, DRS, and PL analysis. The Bi2MoO6/TiO2 composite with different molar ratios of Bi2MoO6 to TiO2 (1, 1/2, 1/3, 1/4, 1/5, and 1/6) showed enhanced photocatalytic activity compared to pure Bi2MoO6 and TiO2. In comparison to bulk Bi2MoO6 and TiO2, the formation of a heterojunction between Bi2MoO6 and TiO2 leads to enhanced CO2 adsorption capacity. The enhanced performance of composites can be ascribed to the improved efficiency of light harvesting in the visible light range and suppressing charge recombination. The composite photocatalytic activity indicated that the ratio of Bi2MoO6 to TiO2 in the composite samples influenced the photocatalytic performance. The Bi2MoO6/TiO2 composite with 1/4 molar ratio had the best performance in 8 h (36.4 μmol/gcat), which was about 10 and 3 times higher than TiO2 and Bi2MoO6 photocatalysts, respectively. Under UV-visible light irradiation, the Pt-Cu@BMT4 sample produced the highest amount of methane (83.6 μmol/gcat) during CO2 photoreduction. During four irradiation cycles, the Pt-Cu@BMT4 sample exhibited superior stability with less than 5% decrease in methane production.

Progress on simultaneous photocatalytic degradation of pollutants and production of clean energy: A review

In the current era of severe energy and environmental crises, the need for efficient and sustainable methods to control pollution and promote resource recycling has become increasingly important. Photocatalytic degradation of pollutants and simultaneous production of clean energy is one such approach that has garnered significant attention in recent years. The principle of photocatalysis involves the development of efficient photocatalysts and the efficient utilization of solar energy. The use of organic contaminants can enhance the photocatalytic reactions, leading to the sustainable generation of clean energy. Herein, we provide a comprehensive review of the latest advances in the application of photocatalytic synergized clean energy production in the environmental field. This review highlights the latest developments and achievements in this field, highlighting the potential for this approach to revolutionize the way we approach environmental pollution control and resource recycling. The review focuses on (1) the mechanism of photocatalytic degradation and synergistic energy production, (2) photocatalysts and synthesis strategies, (3) photocatalytic carbon dioxide reduction, (4) pollutant degradation, and (5) hydrogen and electricity production. In addition, perspectives on key challenges and opportunities in photocatalysis and clean energy for future developments are proposed. This review provides a roadmap for future research directions and innovations of photocatalysis that could contribute to the development of more sustainable and cleaner energy solutions.

Insights into the highly efficient SPR enhanced photodegradation of tetracycline by Bi/Bi2MoO6 composites

A Bi/Bi₂MoO₆ nanocomposite is fabricated utilizing a simple one-pot solvothermal method, which shows great photodegradation ability to tetracycline (TC). The effect of Bi⁰ nanoparticles on the photodegradation of TC was investigated, and it is ascribed to the surface plasmonic resonance (SPR) effect. The light energy could be strongly absorbed by the Bi⁰ nanoparticles, and then transferred to the adjacent Bi₂MoO₆, to enhance the photocatalytic performance. The results of the sacrifice experiment and quantitative analysis of active radicals showed that the photoelectrons could react with soluble O₂ and ·OH to form ·O₂^-, which finally dominates in the process of photocatalytic degradation of TC. This work proposed a way to construct a highly efficient photocatalyst based on SPR effect, which has great application potential in environmental treatment.

Recent trends in Bi-based nanomaterials: challenges, fabrication, enhancement techniques, and environmental applications

One of the most enticing approaches to environmental restoration and energy conversion is photocatalysis powered by solar light. Traditional photocatalysts have limited practical uses due to inadequate light absorption, charge separation, and unknown reaction mechanisms. Discovering new visible-light photocatalysts and investigating their modification is crucial in photocatalysis. Bi-based photocatalytic nanomaterials have gotten much interest as they exhibit distinctive geometric shapes, flexible electronic structures, and good photocatalytic performance under visible light. They can be employed as stand-alone photocatalysts for pollution control and energy production, but they do not have optimum efficacy. As a result, their photocatalytic effectiveness has been significantly improved in the recent decades. Numerous newly created concepts and methodologies have brought significant progress in defining the fundamental features of photocatalysts, upgrading the photocatalytic ability, and understanding essential reactions of the photocatalytic process. This paper provides insights into the characteristics of Bi-based photocatalysts, making them a promising future nanomaterial for environmental remediation. The current review discusses the fabrication techniques and enhancement in Bi-based semiconductor photocatalysts. Various environmental applications, such as H₂ generation and elimination of water pollutants, are also discussed in terms of semiconductor photocatalysis. Future developments will be guided by the uses, issues, and possibilities of Bi-based photocatalysts.

A review on bismuth-based nanocomposites for energy and environmental applications

Bismuth, a heavy metal which is found to be inexpensive and at a reduced cost, is utilized in the synthesis of different nanomaterials with novel structure, remarkable physical and chemical properties, adjustable bandgap, notable efficiency for photothermal conversion. These characteristics have made this element desirable for various applications such as storage and conversion of energy, electronics, sensors, photocatalysis, and other biomedical applications. These review papers are the vital points for the students, this report guides them to the research papers which focus on the impressive development in the area of bismuth and similar nanostructures. The purpose of the present review is to discuss the various synthesis routes of bismuth-based nanomaterials along with green synthesis, different nanostructures of bismuth, their significant properties, diverse applications and directions for the upcoming research. Therefore, with these different tuneable synthesis methods of bismuth-based nanomaterials combined with their novel properties, would elucidate on the future devices based on various nanostructures of bismuth.

Engineering hierarchical FeS2/TiO2 nanotubes on Ti mesh as a tailorable flow-through catalyst belt for all-day-active degradation of organic pollutants and pathogens

The increasing organic and microbiological pollutions in fresh water caused by human activities and industrial development have become a global concern nowadays. In this study, three-dimensional (3D) hierarchical FeS₂/TiO₂ structures with nanotube geometries were grown on a Ti mesh (M-TNTAs-FeS₂). Benefitting from the abundant available reactive sites on the open 3D micro/nanoporous structures, excellent photocatalytic activity of FeS₂/TiO₂ heterostructure in solar light, and satisfactory Fenton activity of FeS₂, the obtained M-TNTAs-FeS₂ exhibits outstanding performance as an all-day-active catalyst. Importantly, flexible meshes can be easily tailored and enveloped into fluorinated ethylene propylene (FEP) pockets in a series as a flow-through belt for large-capacitance applications (998 L m^-2 at a flow rate of 417 L m^-2 h^-1 for a four-pockets belt), as indicated by the degradation of azo dyes, antibiotics, pesticides, and pathogens. This study may inspire a new tailorable catalyst design for a promising point-of-use purification device.

A review on hierarchical Bi2MoO6 nanostructures for photocatalysis applications

This overview provides comprehensive understanding and development trends of hierarchical Bi2MoO6 nanostructures as photocatalysts for efficient photocatalysis applications.

Hybrid Inorganic-Organic Visible-Light-Driven Microrobots Based on Donor-Acceptor Organic Polymer for Degradation of Toxic Psychoactive Substances

Light-driven microrobots based on organic semiconductors have received tremendous attention in the past few years due to their unique properties, such as ease of reactivity tunability, band-gap modulation, and low cost. However, their fabrication with defined morphologies is a very challenging task that results in amorphous microrobots with poor motion efficiencies. Herein, we present hybrid inorganic-organic photoactive microrobots with a tubular shape and based on the combination of a mesoporous silica template with an active polymer containing thiophene and triazine units (named as Tz-Th microrobots). Owing to their well-defined tubular structure, such Tz-Th microrobots showed efficient directional motion under fuel-free conditions. Depending on the accumulation of the polymer coating, these microdevices also exhibited stand-up and rotation motion. As a proof-of-concept, we use these hybrid microrobots for the capture and degradation of toxic psychoactive drugs commonly found in wastewater effluents such as methamphetamine derivatives. We found that the microrobots were able to decompose the drug into small organic fragments after 20 min of visible light irradiation, reaching total intermediates removal after 2 h. Therefore, this approach represents a versatile and low-cost strategy to fabricate structured organic microrobots with efficient directional motion by using inorganic materials as the robot chassis, thereby maintaining the superior photocatalytic performance usually associated with such organic polymers.

Simultaneously removal of Cr(VI) and Cd(II) from water using a flower-like primary battery nanosystem

In this study, a new flower-like primary battery nanosystem termed "Zn/CCP/ZIF-8" was prepared by depositing conductive carbon paint (CCP) and zeolitic imidazolate framework-8 (ZIF-8) on a zinc plate (Zn). Therein, CCP had good conductivity performance and adhesiveness, ZIF-8 and Zn/CCP/ZIF-8 possessed BET specific surface areas of 1909.5 and 1265.4 m²/g respectively. The results showed that the Zn/CCP/ZIF-8 nanosystem could effectively simultaneously adsorb hexavalent chromium (Cr(VI)) and bivalent cadmium (Cd(II)) from water. The system could promote the transfer of electrons from Zn to Cr(VI) and Cd(II) which were effectively reduced to trivalent chromium (Cr(III)) and cadmium (Cd), respectively. The resultant Zn/CCP/ZIF-8/Cr/Cd composite was then easily separated from water. The adsorption isotherm, kinetics, and thermodynamics of the prepared Zn/CCP/ZIF-8 for Cr(VI) and Cd(II) were investigated. An electrochemistry performance test proved that the Zn/CCP/ZIF-8 system was a primary battery. Notably, the Zn/CCP/ZIF-8 system substantially reduced the amounts of Cr(VI) and Cd(II) absorbed by zebrafish and water spinach, thus increasing food safety. The results of a rat test indicated that the Zn/CCP/ZIF-8 system possessed a high biosafety. This study provides a promising, eco-friendly, and facile method for the simultaneously treatment of Cr(VI) and Cd(II) contamination of water.

4-Hydroxyl-oxoisoaporphine, one small molecule as theranostic agent for simultaneous fluorescence imaging and photodynamic therapy as type II photosensitizer

Oxoisoaporphine (OA) is a plant phototoxin isolated from Menispermaceae, however, its weak fluorescence and low water solubility impede it for theranostics. We developed here 4-hydroxyl-oxoisoaporphine (OHOA), which has good singlet oxygen-generating ability (0.06), strong fluorescence (0.72) and improved water solubility. OHOA displays excellent fluorescence for cell imaging and exhibits light-induced cytotoxicity against cancer cell. In vitro model of human cervical carcinoma (HeLa) cell proved that singlet oxygen generated by OHOA triggered photosensitized oxidation reactions and exert toxic effect on tumor cells. The MTT assay using HeLa cells verified the low cytotoxicity of OHOA in the dark and high phototoxicity. Confocal experiment indicates that OHOA mainly distributes in mitochondria and western blotting demonstrated that OHOA induces cell apoptosis via the mitochondrial pathway in the presence of light. Our molecule provides an alternative choice as a theranostic agent against cancer cells which usually are in conflict with each other for most traditional theranostic agents.

Characteristics and Behavior of Different Catalysts Used for Water Decontamination in Photooxidation and Ozonation Processes

The objective of this study was to summarize the results obtained in a wide research project carried out for more than 15 years on the catalytic activity of different catalysts (activated carbon, metal–carbon xerogels/aerogels, iron-doped silica xerogels, ruthenium metal complexes, reduced graphene oxide-metal oxide composites, and zeolites) in the photooxidation (by using UV or solar radiation) and ozonation of water pollutants, including herbicides, naphthalenesulfonic acids, sodium para-chlorobenzoate, nitroimidazoles, tetracyclines, parabens, sulfamethazine, sodium diatrizoate, cytarabine, and surfactants. All catalysts were synthesized and then texturally, chemically, and electronically characterized using numerous experimental techniques, including N2 and CO2 adsorption, mercury porosimetry, thermogravimetric analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis spectroscopy, photoluminescence analysis, and transmission electron microscopy. The behavior of these materials as photocatalysts and ozonation catalysts was related to their characteristics, and the catalytic mechanisms in these advanced oxidation processes were explored. Investigations were conducted into the effects on pollutant degradation, total organic carbon reduction, and water toxicity of operational variables and the presence of different chemical species in ultrapure, surface, ground, and wastewaters. Finally, a review is provided of the most recent and relevant published studies on photocatalysis and catalyzed ozonation in water treatments using similar catalysts to those examined in our project.

Controllable Hydrothermal Synthesis and Photocatalytic Performance of Bi2MoO6 Nano/Microstructures

Bi2MoO6 with a tunable morphology was synthesized by a facile hydrothermal route using different surfactants, including nanosheet-assembled microspheres, smooth microspheres, nanoparticle aggregates and nanoparticles. The morphology, crystal structure and photocatalytic activity of as-obtained Bi2MoO6 were characterized by scanning electron microscopes (SEM), X-ray diffraction (XRD), photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and UV–Vis spectrophotometer. Bi2MoO6 flower-like microspheres using cetyl-trimethyl-ammonium bromide (BET) as the surfactant exhibited much better photocatalytic activity than Bi2MoO6 with the other morphologies, with a degradation efficiency of 98.4%. It can be summarized that the photocatalytic activity of Bi2MoO6 samples depends on their morphology and composition.