Full solar spectrum light driven thermocatalysis with extremely high efficiency on nanostructured Ce ion substituted OMS-2 catalyst for VOCs purification

Enhancing CO catalytic oxidation performance over Cu-doping manganese oxide octahedral molecular sieves catalyst

The CO oxidation catalytic activity of catalysts is strongly influenced by the oxygen vacancy defects (OVDs) concentration and the valence state of active metal. Herein, a defect engineering approach was implemented to enhance the oxygen vacancy defects and to modify the valence of metal ions in manganese oxide octahedral molecular sieves (OMS-2) by the introduction of copper (Cu). The characterization and theoretical calculation results reveal that the incorporation of Cu2+ ion into the OMS-2 structure led to a rise in specific surface area and pore volume, weakening of Mn-O bonds, higher proportion of the low-coordinated oxygen species adsorbed in oxygen vacancies (Oads) and an increase in the average oxidation state of manganese. These structural modifications were discovered to considerably reduce the apparent activation energy (Ea), thus ultimately significantly enhancing the CO oxidation activity (T99 at 148 ℃at GHSV = 13,200 h-1) than the original OMS-2 (T99 = 215 ℃ at GHSV = 13,200 h-1). Furthermore, In-situ diffuse reflectance infrared Fourier transform (DRIFT) and In-situ near-ambient pressure X-ray photoelectron spectroscopy (in situ NAP-XPS) results indicate that the bimetallic synergy enhanced by doping strategy accelerates the conversion of oxygen to chemisorbed oxygen species and the reaction rate of CO oxidation through Mn3++Cu2+↔Mn4++Cu+ redox cycle. The findings of this study offer novel perspectives on the design of catalysts with exceptional performance in CO oxidation.

Advances in Hierarchical Inorganic Nanostructures for Efficient Solar Energy Harvesting Systems

The urgent need to address the global energy and environmental crisis necessitates the development of efficient solar-power harvesting systems. Among the promising candidates, hierarchical inorganic nanostructures stand out due to their exceptional attributes, including a high specific surface area, abundant active sites, and tunable optoelectronic properties. In this comprehensive review, we delve into the fundamental principles underlying various solar energy harvesting technologies, including dye-sensitized solar cells (DSSCs), photocatalytic, photoelectrocatalytic (water splitting), and photothermal (water purification) systems, providing a foundational understanding of their operation. Thereafter, the discussion is focused on recent advancements in the synthesis, design, and development of hierarchical nanostructures composed of diverse inorganic material combinations, tailored for each of these solar energy harvesting systems. We meticulously elaborate on the distinct synthesis methods and conditions employed to fine-tune the morphological features of these hierarchical nanostructures. Furthermore, this review offers profound insights into critical aspects such as electron transfer mechanisms, band gap engineering, the creation of hetero-hybrid structures to optimize interface chemistry through diverse synthesis approaches, and precise adjustments of structural features. Beyond elucidating the scientific fundamentals, this review explores the large-scale applications of the aforementioned solar harvesting systems. Additionally, it addresses the existing challenges and outlines the prospects for achieving heightened solar-energy conversion efficiency.

Full solar spectrum-driven Cu2O/PDINH heterostructure with enhanced photocatalytic antibacterial activity and mechanism insight

Marine biofouling hazards the sustainable development of the environment and has become a potential threat to environmental and ecological security. Photocatalytic antibacterial agents driven by the full solar spectrum are promising antifouling agents for environmental protection. The cuprous oxide/perylene-3,4,9,10-tetracarboximide (Cu₂O/PDINH) heterostructure was successfully constructed by integrating p-type Cu₂O and n-type PDINH to improve photocatalytic antibacterial efficiency. PDINH extended the absorption spectrum from ultraviolet to near-infrared, improving light utilization by 75 %. The Cu₂O/PDINH heterostructure reduced the toxicity risk of Cu₂O for environmental pollution, achieved full solar spectrum drive and overcame the inherent defect that Cu₂O cannot produce singlet oxygen. The Cu₂O/PDINH heterostructure exhibited excellent long-term and photocatalytic antibacterial activity with an antibacterial rate of > 90 % due to the sterilization of copper ions and the continuous generation of ROS driven by the full solar spectrum. This inorganic-organic Cu₂O/PDINH heterostructure shows great application prospects in energy and the environment. The Cu₂O/PDINH heterostructure with effective ROS increase and superior photocatalytic sterilization efficiency has great potential for environmentally friendly marine antifouling agents.

Phytic Acid Doped Polypyrrole as a Mediating Layer Promoting Growth of Prussian Blue on Cotton Fibers for Solar-Driven Interfacial Water Evaporation

Phytic acid doped polypyrrole (PPy) as a mediating layer was in-situ coated on cotton fibers (CFs) to promote the growth of Prussian blue (PB) and construct the PB/PPy@CFs composite. The results showed that the proper amounts of PA doped PPy in-situ generated significantly promoted the growth of PB on CFs, the PB deposition ratio increased from 12.29% (PB@CFs) to 32.4% (PB/PPy@CFs), and the growth of PB on PPy@CFs could be completed in 4 h. Scanning electron microscopy (SEM) showed that the PB particles with perfect nano cubic structure were formed in the composite. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that both PB and PPy were successfully deposited on CFs. The PB/PPy@CFs composite had excellent light absorption, hydrophilicity, wettability, and photothermal property, and the surface could be heated up to 81.5 °C under one sun illumination. The PB/PPy@CFs composite as a photothermal conversion material was used for solar-driven interfacial water evaporation, the water evaporation rate was 1.36 kg·m-2·h-1 at the optical concentration of 1 kW·m2, and the corresponding photothermal conversion efficiency increased from 81.69% (PB@CFs) to 90.96% (PB/PPy@CFs).

Ternary multifunctional catalysts of polymeric carbon nitride coupled with Pt-embedded transition metal oxide to enhance light-driven photothermal catalytic degradation of VOCs

Light driven photothermal catalysis has been carried out by converting the light energy into heat to reach the light-off temperature of the reaction. Herein we have synthesized the ternary multifunctional catalysts of polymeric carbon nitride coupled with Pt-embedded transition metal oxide (Pt-Co_x/CN), for the catalytic degradation of toluene. Under the condition of space velocity of 30,000 mL/(gh) and concentration of 210 ppm, toluene conversion and CO₂ mineralization can reach 90% and 83% over Pt-Co₂₀/CN, respectively. The introduction of an appropriate proportion of CoO enhances the light absorption of nanocomposites and improves the adsorption for toluene. Meanwhile, CoO promotes the proportion and mobility of adsorbed oxygen on the surface, which are conducive to the catalytic oxidation reaction according to the Mars-van Krevelen mechanism. The results also suggest that light irradiation serves as a source of heat to initiate photo-induced chemical reactions and promote photothermal catalytic oxidation by promoting the activation of lattice oxygen.

Recent Progress of Thermocatalytic and Photo/Thermocatalytic Oxidation for VOCs Purification over Manganese-based Oxide Catalysts

Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/thermocatalysis. This article summarizes the research and development on various manganese-based oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Potassium-incorporated manganese oxide enhances the activity and durability of platinum catalysts for low-temperature CO oxidation

Potassium-incorporated manganese oxide is demonstrated as an efficient support for fabricating highly active and stable Pt catalysts for low-temperature CO oxidation.

Oxide-based composites: applications in thermo-photocatalysis

Recent progress on oxide-based thermo-photocatalytic composite systems. Role of plasmonic, defect-related, and thermal effects on the catalytic performance.

Enhanced photothermal catalytic degradation of toluene by loading Pt nanoparticles on manganese oxide: Photoactivation of lattice oxygen

Light-driven photothermocatalysis can provide enough energy to reach light-off temperature of VOCs on the surface of catalyst without auxiliary heat source. Herein, we synthesized noble-metal supported manganese oxide catalysts (xPt/MO) and studied their photothermal catalytic behavior of toluene degradation, where 1 Pt/MO (1 wt.% loading of Pt) and 2 Pt/MO (2 wt.% loading of Pt) exhibited more than 90 % of conversion and 70 % of mineralization under illumination of 200 mW/cm² light intensity with a value of 30,000 mL/(g·h) for weight hourly space velocity (WHSV), respectively. Comparison to pure MO, 1 Pt/MO owns a good photothermal catalytic stability for at least 60 h without obvious deactivation. The introduction of Pt promotes the crystallization of MO (verified by XRD and TEM analysis) and enhances the mobility of surface/sub-surface lattice oxygen (verified by O₂-TPD, H₂-TPR and CO consumption). It is proved that illumination not only supplies thermal energy to trigger the reaction of toluene oxidation but also further evoke more lattice oxygen on Pt/MO to participate in toluene decomposition.

Visible and near-infrared driven Yb3+/Tm3+ co-doped InVO4 nanosheets for highly efficient photocatalytic applications

To effectively enhance the utilization of clean sunlight energy, harvesting a large percentage of near infrared (NIR) light is significant. One of the commonly used effective methods for modifying semiconductors is by co-doping upconversion materials on semiconductors to heighten the photocatalytic efficiency. In this work, Yb3+/Tm3+ co-doped InVO4 nanosheets were synthesized by a facile hydrothermal path, and the crystal phases, morphologies, surface chemical compositions, as well as optical properties were characterized. Yb3+/Tm3+ co-doped InVO4 revealed significantly enhanced photoactivity towards chromium(vi) reduction and methyl orange oxidation under visible or NIR light irradiation. Furthermore, 5YT-IV presented the highest electrocatalytic performance and photocatalytic production of H2O2 under visible light irradiation, requiring low overpotential and low Tafel slope (390 mV dec-1) for hydrogen evolution reaction than that of the bare InVO4 (731 mV dec-1), and as well improved the yield of photocatalytic H2O2 production by about 3.5 times. This was primarily ascribed to intensive light absorption resulting from the benign upconversion energy transfer of Yb3+/Tm3+ and the boosted charge separation caused by the intermediate energy states. Moreover, the presence of h+ and ˙O2- as the main oxidative species played a significant role during the photocatalytic oxidation process of methyl orange and electrons played a decisive role in Cr(vi) reduction. This study provides a promising platform for efficiently utilizing the visible-NIR energy of sunlight in the field of photocatalytic H2O2 production and for alleviating environmental pollution in future.

OMS-2-based catalysts with controllable hierarchical morphologies for highly efficient catalytic oxidation of formaldehyde

Cryptomelane-type octahedral molecular sieve (OMS-2) catalysts are currently attracting tremendous attention due to their low-cost and remarkable thermo-catalytic activity. However, it is still difficult for OMS-2 catalysts to completely degrade formaldehyde at relatively low or even ambient temperature. In this work, OMS-2 catalysts with different ratios of length to diameter were prepared and the OMS-2-s with the minim ratio of length to diameter (1-3) exhibited the best catalytic performance than the other samples. Then, the optimized OMS-2-s nanorods were loaded on the SiO₂ nanofibers via a simultaneous electrospining-spray strategy. The evaluation for the dynamic catalytic activities of the samples showed that, the T₅₀ (HCHO conversion reached to 50%) for the OMS-2/SiO₂ nanofibrous membranes was decreased by 24 °C than the OMS-2-s nanorods. Furthermore, in the static experiment of HCHO decomposition, the composite membrane could achieve a catalytic efficiency of 52.3% at 25 °C, much higher than that of the OMS-2-s nanorods (45.9%). This work offers a new strategy to improve the catalytic efficiency of OMS-2 by controlling the morphology and loading of OMS-2 nanorods, and also designs a kind of advanced nano OMS-2-based nanofibrous membranes with hierarchical nanostructures for the highly efficient formaldehyde elimination during the practical application.

Thermo-Photocatalysis: Environmental and Energy Applications

Catalysis is an integral part of a majority of chemical operations focused on the generation of value-added chemicals or fuels. Similarly, the extensive use of fossil-derived fuels and chemicals has led to deterioration of the environment. Catalysis currently plays a key role in mitigating such effects. Thermal catalysis and photocatalysis are two well-known catalytic approaches that were applied in both energy and environmental fields. Thermo-photocatalysis can be understood as a synergistic effect of the two catalytic processes with key importance in the use of solar energy as thermal and light source. This Review provides an update on relevant contributions about thermo-photocatalytic systems for environmental and energy applications. The reported activity data are compared with the conventional photocatalytic approach and the base of the photothermal effect is analyzed. Some of the systems based on the positive aspects of thermo- and photocatalysis could be the answer to the energy and environmental crisis when taking into account the outstanding results with regard to chemical efficiency and energy saving.

Low-valence or tetravalent cation doping of manganese oxide octahedral molecular sieve (K-OMS-2) materials for nitrogen oxide emission abatement

Substitutionally doped oxide catalysts with abundant oxygen vacancy defects (OVDs) can effectively improve the catalytic activity efficiency.

Pt nanoparticles decorated rose-like Bi2O2CO3 configurations for efficient photocatalytic removal of water organic pollutants

Pt nanoparticles decorated with rose-like Bi₂O₂CO₃ configurations were synthesized via a simple photoreduction method at room temperature.

Insights into the solar light driven thermocatalytic oxidation of VOCs over tunnel structured manganese oxides

Tunnel structured manganese oxides with high photothermal performance were prepared, and their light driven thermocatalytic activity was carefully investigated.

Solar-driven broad spectrum fungicides based on monodispersed Cu7S4 nanorods with strong near-infrared photothermal efficiency

Cu₇S₄ nanorods were used for the first time as broad spectrum fungicides for efficient bacterial disinfection via natural sunlight irradiation.