Roll-to-roll synthesis of multielement heterostructured catalysts
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Advanced Oxidation Processes (AOPs) are promising for treating persistent pollutants, yet challenges arise due to the step-wise oxidants activation process, which traditional single-active-center catalysts struggle to facilitate effectively. Recently, dual-active-center catalysts have emerged as a solution by enabling synergistic reactions. This review covers advances in these catalysts, their co-catalytic mechanisms, and applications in electro-Fenton, photocatalytic, peroxymonosulfate-, and pollutant-as-electron-donor based Fenton-like processes, along with active site design considerations and future challenges.
Effects of nitrogen vacancy sites of oxynitride support on the catalytic activity for ammonia decomposition
Nitrogen-containing compounds such as imides and amides have been reported as efficient materials that promote ammonia decomposition over nonnoble metal catalysts. However, these compounds decompose in an air atmosphere and become inactive, which leads to difficulty in handling. Here, we focused on perovskite oxynitrides as air-stable and efficient supports for ammonia decomposition catalysts. Ni-loaded oxynitrides exhibited 2.5–18 times greater catalytic activity than did the corresponding oxide-supported Ni catalysts, even without noticeable differences in the Ni particle size and surface area of the supports. The catalytic performance of the Ni-loaded oxynitrides is well correlated with the nitrogen desorption temperature during N2 temperature-programmed desorption, which suggests that the lattice nitrogen in the oxynitride support rather than the Ni surface is the active site for ammonia decomposition. Furthermore, NH3 temperature-programmed surface reactions and density functional theory (DFT) calculations revealed that NH3 molecules are preferentially adsorbed on the nitrogen vacancy sites on the support surface rather than on the Ni surface. Thus, the ammonia decomposition reaction is facilitated by a vacancy-mediated reaction mechanism.
Floating 3D-PDMS-Iron oxide molecular baskets for decontaminating diverse pollutants and analyzing structural composition impacts
Novel iron oxide-incorporated porous polydimethylsiloxane sponges were developed using a simple, non-toxic two-step process. Characterized through various techniques, these sponges serve as effective photocatalysts, absorbents, and adsorbents for pollutant removal. They demonstrated nearly 100% degradation of rhodamine B under optimal conditions ( ~ 100% with Xe arc lamp, 50 mg, pH 3-9, and 4 h), following a pseudo second-order kinetic model (r2 = 0.9999). The sponges also exhibited good activity for other pollutants, including methylene blue (76–87%), 1,4-dichlorobenzene (57–71%), and azithromycin (82–87%), and maintained high performance over 11 reuse cycles with minimal iron loss. In addition, fresh and used catalysts effectively separated oils (173–680 mg with 50 mg of absorbent, and 10–15 s) and chromium (VI) [~87% with 1 ppm, 50 mg, pH 7, and 24 h] from water. This environmentally sustainable approach produces no toxic waste and allows for simple regeneration, making it a promising solution for the water treatment industry.
Modeling the impact of structure and coverage on the reactivity of realistic heterogeneous catalysts
Adsorbates often cover the surfaces of catalysts densely as they carry out reactions, dynamically altering their structure and reactivity. Understanding adsorbate-induced phenomena and harnessing them in our broader quest for improved catalysts is a substantial challenge that is only beginning to be addressed. Here we chart a path toward a deeper understanding of such phenomena by focusing on emerging in silico modeling methodologies, which will increasingly incorporate machine learning techniques. We first examine how adsorption on catalyst surfaces can lead to local and even global structural changes spanning entire nanoparticles, and how this affects their reactivity. We then evaluate current efforts and the remaining challenges in developing robust and predictive simulations for modeling such behavior. Last, we provide our perspectives in four critical areas—integration of artificial intelligence, building robust catalysis informatics infrastructure, synergism with experimental characterization, and adaptive modeling frameworks—that we believe can help surmount the remaining challenges in rationally designing catalysts in light of these complex phenomena.
Photo-assisted technologies for environmental remediation
Industrial processes can lead to air and water pollution, particularly from organic contaminants such as toluene and antibiotics, posing threats to human health. Photo-assisted chemical oxidation technologies leverage light energy to mineralize these contaminants. In this Review, we discuss the mechanisms and efficiencies of photo-assisted advanced oxidation processes for wastewater treatment and photothermal technologies for air purification. The integration of solar energy enhances degradation efficiency and reduces energy consumption, enabling more efficient remediation methods. We evaluate the technological aspects of photo-assisted technologies, such as photo-Fenton, photo-persulfate activation, photo-ozonation and photoelectrochemical oxidation, emphasizing their potential for practical applications. Finally, we discuss the challenges in scaling up photo-assisted technologies for specific environmental remediation needs. Photo-assisted technologies have demonstrated effectiveness in environmental remediation, although large-scale applications remain constrained by high costs. Future potential applications of photo-assisted technologies will require that technology selection be tailored to specific pollution scenarios and engineering processes optimized to minimize costs.
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