Search Results (20)

Carbon catalysts have shown promise as an alternative to the currently available energy-intensive approaches for nitrogen fixation (NF) to urea, NH₃, or related nitrogenous compounds. The primary challenges for NF are the natural inertia of nitrogenous molecules and the competitive hydrogen evolution reaction (HER). Recently, carbon-based materials have made significant progress due to their tunable electronic structure and ease of defect formation. These properties significantly enhance electrocatalytic and photocatalytic nitrogen reduction reaction (NRR) activity. While transition metal-based catalysts have solved the kinetic constraints to activate nitrogen bonds via the donation-back-π approach, there is a problem: the d-orbital electrons of these transition metal atoms tend to generate H-metal bonds, inadvertently amplifying unwanted HER. Because of this, a timely review of defective carbon-based electrocatalysts for NF is imperative. Such a review will succinctly capture recent developments in both experimental and theoretical fields. It will delve into multiple defective engineering approaches to advance the development of ideal carbon-based electrocatalysts and photocatalysts. Furthermore, this review will carefully explore the natural correlation between the structure of these defective carbon-based electrocatalysts and photocatalysts and their NF activity. Finally, novel carbon-based catalysts are introduced to obtain more efficient performance of NF, paving the way for a sustainable future. Full article

Metal–organic frameworks (MOFs) represent a category of crystalline materials formed by the combination of metal ions or clusters with organic linkers, which have emerged as a prominent research focus in the field of photocatalysis. Owing to their distinctive characteristics, including structural diversity and configurations, significant porosity, and an extensive specific surface area, they provide a flexible foundation for various potential applications in photocatalysis. In recent years, researchers have tackled many issues in the MOF-based photocatalytic yield. However, limited light adsorption regions, lack of active sites and active species, and insufficient efficiency of photogenerated charge carrier separation substantially hinder the photocatalytic performance. In this review, we summarized the strategies to improve the photocatalytic performance and recent developments achieved in MOF and MOF-based photocatalysis, including water splitting, CO₂ conversion, photocatalytic degradation of pollutants, and photocatalytic nitrogen fixation into ammonia. In conclusion, the existing challenges and prospective advancements in MOF-based photocatalysis are also discussed. Full article

Implementing greener approaches is a sustainable and eco-friendly methodology for nanocomposite synthesis. This work reports the sustainable fabrication of Fe-doped ZnS (Fe_0.3Zn_0.7S) nanocomposite and its broad-spectrum applications. The systematic characterization was carried out using several advanced analytical techniques. DLS, Zeta potential, SEM, XPS, and TEM performed morphological and size assessments of the engineered nanocomposite. Eventually, XRD provided valuable insights into the crystalline behavior of nanocomposite. The nanocomposites were then treated against the organic dye Safranin O, which displayed 93% degradation within an hour with the rate constant value of 0.0326 min⁻¹. Parameters influencing the percentage degradation, such as temperature, pH, etc., were also discussed. Moreover, an LCMS test was also conducted to evaluate the presence of reactive intermediates. Safranin O’s degradation was confirmed by identifying intermediate products, such as compounds with m/z values of 335.84, 321.81, 306.79, 292.77, and 257.32, which were indicative of progressive dye breakdown. Finally, the photocatalytic enactment examination verified that the prepared nanocomposite’s nitrogen fixation rate (38.96 µmolg⁻¹) was way greater (~4 times) than the pristine compound. In addition, prepared nanoparticles demonstrated a befitting ability to eliminate a wide range of threatening pathogenic fungi. The doping of Fe into ZnS further enhanced the inhibition against Fusarium oxysporum. Full article

The conversion of nitrogen (N₂) and water (H₂O) into NH₃ by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N₂ fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO₂ derived from NH₂-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N₂ fixation. It was found that the photocatalytic N₂ reduction efficiency of bimetallic FC@TiO₂-JH was improved, enabling an NH₃ yield rate of 110.14 µmol g⁻¹ h⁻¹ without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO₂-JH and Co@TiO₂-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N₂ while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO₂-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N₂ at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH₂-MIL-125(Ti) for N₂ fixation. Full article

Ammonia, as the second most-produced chemical worldwide, serves diverse roles in the industrial and agricultural sectors. However, its conventional production via the Haber–Bosch process poses significant challenges, including high energy consumption and carbon dioxide emissions. In contrast, photocatalytic nitrogen (N₂) fixation, utilizing solar energy with minimal emissions, offers a promising method for sustainable ammonia synthesis. Despite ongoing efforts, photocatalytic nitrogen fixation catalysts continue to encounter challenges such as inadequate N₂ adsorption, limited light absorption, and rapid photocarrier recombination. This review explores how the electronic structure and surface characteristics of one-dimensional nanomaterials could mitigate these challenges, making them promising photocatalysts for N₂ fixation. The review delves into the underlying photocatalytic mechanisms of nitrogen fixation and various synthesis methods for one-dimensional nanomaterials. Additionally, it highlights the role of the high surface area of one-dimensional nanomaterials in enhancing photocatalytic performance. A comparative analysis of the photocatalytic nitrogen fixation capabilities of different one-dimensional nanomaterials is provided. Lastly, the review offers insights into potential future advancements in photocatalytic nitrogen fixation. Full article

Metal-organic frameworks (MOFs) are a novel category of porous crystalline materials with an exceptionally high surface area and adjustable pore structure. They possess a designable composition and can be easily functionalized with different units. Porphyrins with conjugated tetrapyrrole macrocyclic structures can absorb light from ultraviolet to visible light regions, and their structures and properties can be facilely regulated by altering their peripheral groups or central metal ions. Porphyrin-based MOFs constructed from porphyrin ligands and metal nodes combine the unique features of porphyrins and MOFs as well as overcoming their respective limitations. This paper reviewed the design and construction, light absorption and charge transfer pathways, and strategy for improving the photocatalytic performance of porphyrin-based MOFs, and highlighted the recent progress in the field of CO₂ reduction, hydrogen evolution, organic synthesis, organic pollutant removal, and nitrogen fixation. The intrinsic relationships between the structure and the property of porphyrin-based MOFs received special attention, especially the relationships between the arrangements of porphyrin ligands and metal nods and the charge transfer mechanism. We attempted to provide more valuable information for the design and construction of advanced photocatalysts in the future. Finally, the challenges and future perspectives of the porphyrin-based MOFs are also discussed. Full article

Photocatalytic nitrogen fixation has attracted much attention because of its ability to synthesize ammonia under mild conditions. However, the ammonia yield is still greatly limited by the sluggish charge separation and extremely high N₂ dissociation energy. Herein, two-dimensional Ti₃C₂ MXene ultrathin nanosheets were introduced to construct Ti₃C₂/TiO₂ composites via electrostatic adsorption for photocatalytic nitrogen fixation. The photocatalytic activity experiments showed that after adding 0.1 wt% Ti₃C₂, the ammonia yield of the Ti₃C₂/TiO₂ composite reached 67.9 μmol L⁻¹ after 120 min of light irradiation, nearly 3 times higher than that of the monomer TiO₂. XPS, DRS, LSV, and FTIR were used to explore the possible photocatalytic nitrogen fixation mechanism. Studies showed that a close interfacial contact has been formed via the bonding mode of =C-O between the Ti₃C₂ and TiO₂ samples. The formed =C-O bond boosts an oriented photogenerated charge separation and transfer in the Ti₃C₂/TiO₂ composite. This work provides a promising idea for constructing other efficient MXene-based composite photocatalysts for artificial photosynthesis. Full article

Ammonia is an essential component of modern chemical products and the building unit of natural life molecules. The Haber–Bosch (H-B) process is mainly used in the ammonia synthesis process in the industry. In this process, nitrogen and hydrogen react to produce ammonia with metal catalysts under high temperatures and pressure. However, the H-B process consumes a lot of energy and simultaneously emits greenhouse gases. In the “double carbon” effect, to promote the combination of photocatalytic technology and artificial nitrogen fixation, the development of green synthetic reactions has been widely discussed. Using an inexhaustible supply of sunlight as a power source, researchers have used photocatalysts to reduce nitrogen to ammonia, which is energy-dense and easy to store and transport. This process completes the conversion from light energy to chemical energy. At the same time, it achieves zero carbon emissions, reducing energy consumption and environmental pollution in industrial ammonia synthesis from the source. The application of photocatalytic technology in the nitrogen cycle has become one of the research hotspots in the new energy field. This article provides a classification of and an introduction to nitrogen-fixing photocatalysts reported in recent years and prospects the future development trends in this field. Full article

This paper presents new photocatalysts obtained by treating carbon spheres (CS) and TiO₂ in a microwave reactor at a pressure of 20 atm and a temperature of up to 300 °C for 15 min and then depositing TiO₂/CS composites on glass fibre cloths. Such highly CO₂-adsorbing photocatalysts showed photoactivity in the simultaneous water-splitting process, generating H₂, reducing CO₂ to CO and CH₄, and reducing N₂ to NH₃. In addition, calculations of the hydrogen balance involved in all reactions were performed. Adding 1 g of carbon spheres per 1 g of TiO₂ maintained the high selectivity of nitrogen fixation at 95.87–99.5%, which was continuously removed from the gas phase into the water as NH₄⁺ ions. Full article

MXenes (Ti₃C₂T_x) have gotten a lot of interest since their discovery in 2011 because of their distinctive two-dimensional layered structure, high conductivity, and rich surface functional groups. According to the findings, MXenes (Ti₃C₂T_x) may block photogenerated electron-hole recombination in the photocatalytic system and offer many activation reaction sites, enhancing the photocatalytic performance and demonstrating tremendous promise in the field of photocatalysis. This review discusses current Ti₃C₂T_x-based photocatalyst preparation techniques, such as ultrasonic mixing, electrostatic self-assembly, hydrothermal preparation, and calcination techniques. We also summarised the advancements in photocatalytic CO₂ reduction, photocatalytic nitrogen fixation, photocatalytic hydrogen evolution, and Ti₃C₂T_x-based photocatalysts in photocatalytic degradation of pollutants. Lastly, the challenges and prospects of Ti₃C₂T_x in photocatalysis are discussed based on the practical application of Ti₃C₂T_x. Full article

Photocatalysis, as an inexpensive and safe technology to convert solar energy, is essential for the efficient utilization of sustainable renewable energy sources. Earth-abundant cobalt sulfide-based composites have generated great interest in the field of solar fuel conversion because of their cheap, diverse structures and facile preparation. Over the past 10 years, the number of reports on cobalt sulfide-based photocatalysts has increased year by year, and more than 500 publications on the application of cobalt sulfide groups in photocatalysis can be found in the last three years. In this review, we initially summarize the four common strategies for preparing cobalt sulfide-based composite materials. Then, the multiple roles of cobalt sulfide-based cocatalysts in photocatalysis have been discussed. After that, we present the latest progress of cobalt sulfide in four fields of photocatalysis application, including photocatalytic hydrogen production, carbon dioxide reduction, nitrogen fixation, and photocatalytic degradation of pollutants. Finally, the development prospects and challenges of cobalt sulfide-based photocatalysts are discussed. This review is expected to provide useful reference for the construction of high-performance cobalt sulfide-based composite photocatalytic materials for sustainable solar-chemical energy conversion. Full article

In this study, Fe-doped graphitic carbon nitride (Fe-MCNC) with varying Fe contents was synthesized via a supramolecular approach, followed by thermal exfoliation, and was then used for accelerated photocatalytic hydrogen evolution and nitrogen fixation. Various techniques were used to study the physicochemical properties of the MCN (g-C₃N₄ from melamine) and Fe-MCNC (MCN for g-C₃N₄ and C for cyanuric acid) catalysts. The field emission scanning electron microscopy (FE-SEM) images clearly demonstrate that the morphology of Fe-MCNC changes from planar sheets to porous, partially twisted (partially developed nanotube and nanorod) nanostructures. The elemental mapping study confirms the uniform distribution of Fe on the MCNC surface. The X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectroscopy (UV-DRS) results suggest that the Fe species might exist in the Fe³⁺ state and form Fe-N bonds with N atoms, thereby extending the visible light absorption areas and decreasing the band gap of MCN. Furthermore, doping with precise amounts of Fe might induce exfoliation and increase the specific surface area, but excessive Fe could destroy the MCN structure. The optimized Fe-MCNC nanostructure had a specific surface area of 23.6 m² g⁻¹, which was 8.1 times greater than that of MCN (2.89 m² g⁻¹). To study its photocatalytic properties, the nanostructure was tested for photocatalytic hydrogen evolution and nitrogen fixation; 2Fe-MCNC shows the highest photocatalytic activity, which is approximately 13.3 times and 2.4 times better, respectively, than MCN-1H. Due to its high efficiency and stability, the Fe-MCNC nanostructure is a promising and ideal photocatalyst for a wide range of applications. Full article

These days, explorations have focused on designing two-dimensional (2D) nanomaterials with useful (photo)catalytic and environmental applications. Among them, MXene-based composites have garnered great attention owing to their unique optical, mechanical, thermal, chemical, and electronic properties. Various MXene-based photocatalysts have been inventively constructed for a variety of photocatalytic applications ranging from pollutant degradation to hydrogen evolution. They can be applied as co-catalysts in combination with assorted common photocatalysts such as metal sulfide, metal oxides, metal–organic frameworks, graphene, and graphitic carbon nitride to enhance the function of photocatalytic removal of organic/pharmaceutical pollutants, nitrogen fixation, photocatalytic hydrogen evolution, and carbon dioxide conversion, among others. High electrical conductivity, robust photothermal effects, large surface area, hydrophilicity, and abundant surface functional groups of MXenes render them as attractive candidates for photocatalytic removal of pollutants as well as improvement of photocatalytic performance of semiconductor catalysts. Herein, the most recent developments in photocatalytic degradation of organic and pharmaceutical pollutants using MXene-based composites are deliberated, with a focus on important challenges and future perspectives; techniques for fabrication of these photocatalysts are also covered. Full article

Metal–organic frameworks (MOFs) are coordination polymers with high porosity that are constructed from molecular engineering. Constructing MOFs as photocatalysts for the reduction of nitrogen to ammonia is a newly emerging but fast-growing field, owing to MOFs’ large pore volumes, adjustable pore sizes, controllable structures, wide light harvesting ranges, and high densities of exposed catalytic sites. They are also growing in popularity because of the pristine MOFs that can easily be transformed into advanced composites and derivatives, with enhanced catalytic performance. In this review, we firstly summarized and compared the ammonia detection methods and the synthetic methods of MOF-based materials. Then we highlighted the recent achievements in state-of-the-art MOF-based materials for photocatalytic nitrogen fixation. Finally, the summary and perspectives of MOF-based materials for photocatalytic nitrogen fixation were presented. This review aims to provide up-to-date developments in MOF-based materials for nitrogen fixation that are beneficial to researchers who are interested or involved in this field. Full article

Environmental pollution and various diseases seriously affect the health of human beings. Photocatalytic nanomaterials (NMs) have been used for degrading pollution for a long time. However, the biomedical applications of photocatalytic NMs have only recently been investigated. As a typical photocatalytic NM, bismuth oxychloride (BiOCl) exhibits excellent photocatalytic performance due to its unique layered structure, electronic properties, optical properties, good photocatalytic activity, and stability. Some environmental pollutants, such as volatile organic compounds, antibiotics and their derivatives, heavy metal ions, pesticides, and microorganisms, could not only be detected but also be degraded by BiOCl-based NMs due to their excellent photocatalytic and photoelectrochemical properties. In particular, BiOCl-based NMs have been used as theranostic platforms because of their CT and photoacoustic imaging abilities, as well as photodynamic and photothermal performances. However, some reviews have only profiled the applications of dye degradation, hydrogen or oxygen production, carbon dioxide reduction, or nitrogen fixation of BiOCl NMs. There is a notable knowledge gap regarding the systematic study of the relationship between BiOCl NMs and human health, especially the biomedical applications of BiOCl-based NMs. As a result, in this review, the recent progress of BiOCl-based photocatalytic degradation and biomedical applications are summarized, and the improvement of BiOCl-based NMs in environmental and healthcare fields are also discussed. Finally, a few insights into the current status and future perspectives of BiOCl-based NMs are given. Full article