Precursor engineering of hydrotalcite-derived redox sorbents for reversible and stable thermochemical oxygen storage

Enhancement of Ni-NiO-CeO2 Interaction on Ni-CeO2/Al2O3-MgO Catalyst by Ammonia Vapor Diffusion Impregnation for CO2 Reforming of CH4

Ni-based catalysts have been widely used for the CO2 reforming of methane (CRM) process, but deactivation is their main problem. This study created an alternative electronic Ni-NiO-CeO2 interaction on the surface of 5 wt% Ni-5 wt% CeO2/Al2O3-MgO (5Ni5Ce(xh)/MA) catalysts to enhance catalytic potential simultaneously with coke resistance for the CRM process. The Ni-NiO-CeO2 network was developed on Al2O3-MgO through layered double hydroxide synthesis via our ammonia vapor diffusion impregnation method. The physical properties of the fresh catalysts were analyzed employing FESEM, N2 physisorption, and XRD. The chemical properties on the catalyst surface were analyzed employing H2-TPR, XPS, H2-TPD, CO2-TPD, and O2-TPD. The CRM performances of reduced catalysts were evaluated at 600 °C under ambient pressure. Carbon deposits on spent catalysts were determined quantitatively and qualitatively by TPO, FESEM, and XRD. Compared to 5 wt% Ni-5 wt% CeO2/Al2O3-MgO prepared by the traditional impregnation method, the electronic interaction of the Ni-NiO-CeO2 network with the Al2O3-MgO support was constructed along the time of ammonia diffusion treatment. The electronic interaction in the Ni-NiO-CeO2 nanostructure of the treated catalyst develops surface hydroxyl sites with an efficient pathway of OH* and O* transfer that improves catalytic activities and coke oxidation.

Bafi A1 inhibits nano-copper oxide-induced mitochondrial damage by reducing the release of copper from lysosomes

This study demonstrated that both copper oxide nanoparticles (CuO-NPs) and copper nanoparticles (Cu-NPs) can cause swelling, inflammation, and cause damage to the mitochondria of alveolar type II epithelial cells in mice. Cellular examinations indicated that both CuO-NPs and Cu-NPs can reduce cell viability and harm the mitochondria of human bronchial epithelial cells, particularly Beas-2B cells. However, it is clear that CuO-NPs exhibit a more pronounced detrimental effect compared with Cu-NPs. Using bafilomycin A1 (Bafi A1), an inhibitor of lysosomal acidification, was found to enhance cell viability and alleviate mitochondrial damage caused by CuO-NPs. Additionally, Bafi A1 also reduces the accumulation of dihydrolipoamide S-acetyltransferase (DLAT), a marker for mitochondrial protein toxicity, induced by CuO-NPs. This observation suggests that the toxicity of CuO-NPs depends on the distribution of copper particles within cells, a process facilitated by the acidic environment of lysosomes. The release of copper ions is thought to be triggered by the acidic conditions within lysosomes, which aligns with the lysosomal Trojan horse mechanism. However, this association does not seem to be evident with Cu-NPs.

Oxygen vacancy-rich Ag/CuO nanoarray mesh fabricated by laser ablation for efficient bacterial inactivation

The contamination of drinking water by microbes is a critical health concern, underscoring the need for safe, reliable, and efficient methods to treat pathogenic microorganisms. While most sterilization materials are available in powder form, this presents safety risks and challenges in recycling. Herein, this study reports the preparation of an innovative copper oxide supported silver monolithic nanoarray mesh with abundant oxygen vacancies (Ag/CuO-VO) by laser ablation. The instantaneous high temperature caused by laser ablation preserves the material's original structure while generating oxygen vacancies on the CuO surface. The Ag/CuO-VO mesh demonstrated a remarkable ability to inactivate over 99% of Escherichia coli (E. Coli) within 20 min. The oxygen vacancies in the Ag/CuO-VO enhance interactions between oxygen species and the Ag/CuO-VO, leading to the accumulation of large amounts of reactive oxygen species (ROS). The generated ROS effectively disrupt both layers of the bacterial cell wall - the peptidoglycan and the phospholipid - as confirmed by Fourier Transform Infrared (FTIR) spectroscopy, culminating in cell death. This research presents a monolithic material capable of inactivating pathogenic microorganisms efficiently, offering a significant advancement in water sterilization technology.

Chemical Looping Technology in Mild-Condition Ammonia Production: A Comprehensive Review and Analysis

Ammonia is an efficient and clean hydrogen carrier that promises to tackle the increasing energy and environmental problems. However, more than 90% of ammonia is produced by the Haber-Bosch process, and its enormous energy consumption and CO2 emissions require the development of novel alternatives. Chemical looping technology can decouple the one-step ammonia synthesis reaction into separated nitridation and hydrogenation processes at atmospheric pressure, thereby achieving the mild ammonia synthesis based on renewable energy. The strategy of stepwise reactions circumvents the problem of competing adsorption of N2 and H2 /H2 O at the active sites and provides additive freedom for optimal regulation of sub-reactions. This review introduces the concept and mechanism of chemical looping ammonia production (CLAP), and comprehensively summarizes the state-of-art research from the perspective of reaction pathways and nitrogen carriers. The challenges faced by CLAP and strategies to address them in terms of nitrogen carriers, methods, equipment, and technological processes are also proposed.

New Triclinic Perovskite-Type Oxide Ba5CaFe4O12 for Low-Temperature Operated Chemical Looping Air Separation

We present the discovery of Ba5CaFe4O12, a new iron-based oxide with remarkable properties as a low-temperature driven oxygen storage material (OSM). OSMs, which exhibit selective and rapid oxygen intake and release capabilities, have attracted considerable attention in chemical looping technologies. Specifically, chemical looping air separation (CLAS) has the potential to revolutionize oxygen production as it is one of the most crucial industrial gases. However, the challenge lies in utilizing OSMs for energy-efficient CLAS at lower temperatures. Ba5CaFe4O12, a cost-competitive material, possesses an unprecedented 5-fold perovskite-type A5B5O15-δ structure, where both Fe and Ca occupy the B sites. This distinctive structure enables excellent oxygen intake/release properties below 400 °C. This oxide demonstrates the theoretical daily oxygen production rate of 2.41 mO23 kgOSM-1 at 370 °C, surpassing the performance of the previously reported material, Sr0.76Ca0.24FeO3-δ (0.81 mO23 kgOSM-1 at 550 °C). This discovery holds great potential for reducing costs and enhancing the energy efficiency in CLAS.

Hydrotalcite-Derived Copper-Based Oxygen Carrier Materials for Efficient Chemical-Looping Combustion of Solid Fuels with CO2 Capture

Chemical-looping combustion (CLC) is a promising technology that utilizes metal oxides as oxygen carriers for the combustion of fossil fuels to CO₂ and H₂O, with CO₂ readily sequestrated after the condensation of steam. Thermally stable and reactive metal oxides are desirable as oxygen carrier materials for the CLC processes. Here, we report the performance of Cu-based mixed oxides derived from hydrotalcite (also known as layered double hydroxides) precursors as oxygen carriers for the combustion of solid fuels. Two types of CLC processes were demonstrated, including chemical looping oxygen uncoupling (CLOU) and in situ gasification (iG-CLC) in the presence of steam. The Cu-based oxygen carriers showed high performance for the combustion of two solid fuels (a lignite and a bituminous coal), maintaining high thermal stability, fast reaction kinetics, and reversible oxygen release and storage over multiple redox cycles. Slight deactivation and sintering of the oxygen carrier occurred after redox cycles at an very high operation temperature of 985 °C. We expect that our material design strategy will inspire the development of better oxygen carrier materials for a variety of chemical looping processes for the clean conversion of fossil fuels with efficient CO₂ capture.