HCHO Removal Efficiency Research Articles

Selective recovery of platinum from spent catalysts to fabricate platinum/amorphous manganese oxide/corrugated silica carrier for formaldehyde removal

The efficient recovery and reutilization of spent Pt catalysts have two huge challenges in the metallurgical and chemical industries. Herein, platinum was selectively retrieved from spent Pt/γ-Al2O3 catalysts by a microwave-assisted aqua regia digestion strategy, and the as-obtained platinum extract was utilized to prepare a novel Pt/amorphous MnOx/corrugated silica carrier (Pt/MnOx/CSC) catalyst for formaldehyde removal. To decrease consumption of toxic aqua regia, the γ-Al2O3 in the spent catalysts was converted to chemically stabile α-Al2O3 via high-temperature calcination. The high Pt leaching efficiency of 98.31% was achieved at a digestion temperature of 110oC and aqua regia concentration of 40vol%. However, the high leaching temperatures and aqua regia concentrations caused the part dissolution of α-Al2O3, and thus decreased the Pt leaching efficiency. The CSC in the Pt/MnOx/CSC catalysts served as a support, while both the Pt nanoparticles and amorphous MnOx microspheres acted as active catalysts. The synergistical effects between the Pt and amorphous MnOx endowed the composite catalysts with excellent catalytic activity, and the HCHO removal efficiency reached 100% even after five cycle tests. On the one hand, the nanostructured MnOx microspheres provided great surface areas and rich oxygen vacancies for heterogeneous catalysis. On the other hand, the Pt nanoparticles not only enhanced the low-temperature reducibilities of MnOx, but also decreased the apparent activation energies of HCHO catalytic oxidation. This work provided a new strategy for the selective recovery of platinum from spent catalysts and the reutilization of Pt-based catalysts for the HCHO thermal catalytic oxidation.

Assembly of MOFs derived Co-Mn bimetallic oxides on SiO2 nanofibrous membrane for indoor air purification

The development of highly efficient air purification materials contributes to acquiring quality indoor air that essential for improving physical health and life comfort. In this work, a Co3O4-CoMn2O4@SiO2 (COCMOS) nanofibrous membranes (NFMs) were prepared by thermal treating Mn-modified ZIF-67@SiO2 NFMs for efficient indoor air purification. The COCMOS NFMs exhibited 99.03 % and 99.999 % dust retention efficiencies for PM0.3 and PM2.5 with a low filtration resistance, respectively. Compared to the Co3O4@SiO2 (COS) NFMs (23 %), the HCHO removal efficiency of COCMOS NFMs was significantly improved at room temperature, reaching over 95 % within 25 min. The characterization results indicated that the thermal treatment of Mn-modified ZIF-67 induced the formation of a Co3O4-CoMn2O4 heterostructure on the surface of COCMOS NFMs. The Mn-Co bimetallic sites in this heterogeneous structure increased the amounts of oxygen vacancies and high valent cations and enhanced the redox properties of COCMOS NFMs, which contributed to its superior performance. This work provided insights on the design and preparation of highly efficient materials for indoor air purification.

Enhanced and Sustainable Removal of Indoor Formaldehyde by Naturally Porous Bamboo Activated Carbon Supported with MnOx: Synergistic Effect of Adsorption and Oxidation

Novel bamboo activated carbon (BAC) catalysts decorated with manganese oxides (MnOx) were prepared with varying MnOx contents through a facile one-step redox reaction. Due to the physical anchoring effect of the natural macropore structure for catalyst active components, homogeneous MnOx nanoparticles (NPs), and high specific surface area over catalyst surface, the BAC@MnOx-N (N = 1, 2, 3, 4, 5) catalyst shows encouraging adsorption and catalytic oxidation for indoor formaldehyde (HCHO) removal at room temperature. Dynamic adsorption and catalytic activity experiments were conducted. The higher Smicro (733 m2/g) and Vmicro/Vt (82.6%) of the BAC@MnOx-4 catalyst could facilitate its excellent saturated and breakthrough adsorption capacity (5.24 ± 0.42 mg/g, 2.43 ± 0.22 mg/g). The best performer against 2 ppm HCHO is BAC@MnOx-4 catalyst, exhibiting a maximum HCHO removal efficiency of 97% for 17 h without any deactivation as RH = 0, which is higher than those of other MnOx-based catalysts. The average oxidation state and in situ DRIFTS analysis reveal that abundant oxygen vacancies on the BAC@MnOx-4 catalyst could be identified as surface-active sites of decomposing HCHO into the intermediate species (dioxymethylene and formate). This study provides a potential approach to deposit MnOx nanoparticles onto the BAC surface, and this hybrid BAC@MnOx material is promising for indoor HCHO removal at room temperature.

Logical formulation and in-situ assembly of MnCo2O4@MnO2 nanoflower arrays on nickel foam as monolithic catalyst for formaldehyde degradation at indoor temperature

The development and design of efficient and cost-effective catalysts for oxidizing low concentrations of formaldehyde at low temperatures, has been a significant challenge in HCHO oxidation. In this study, MnCo2O4@MnO2-NF (Ni foam) was synthesized as a monolithic catalyst for the degradation of HCHO in indoor environments. Using carrier immobilization, morphology modulation, and doping modification. The results revealed that the Co3O4 nanoarrays could be grown in a directional and orderly manner on the surface of the substrate through morphological modulation, showing a pompom-like, flower-like shape of the nanoneedles, thus providing sufficient growth sites for MnO2. Doping the Co3O4 nanoarrays with Mn via in-situ growth resulted in MnCo2O4 nanoarrays, following which the MnO2 expanded the pore sizes of the sample and provide more surface adsorption sites upon using MnCo2O4 as the carrier. In addition, numerous oxygen vacancies formed on the catalyst surface because of the synergistic interaction between Co and Mn, which formed more Mn3+ species and Oads, resulting in superior low-temperature redox ability and catalytic cycle stability. The catalyst achieved a HCHO removal efficiency of over 85 % within 60 min for five test cycles when the KMnO4 concentration was 0.05 M and Mn/Co ratio was 1:2.

Functional graphitic carbon nitride/hydroxyapatite heterojunction for robust formaldehyde removal at ambient temperature

Ambient-temperature catalytic removal of formaldehyde (HCHO) hazard has been currently reckoned as a practicable and promising approach for abating indoor HCHO which severely haunts the human’s health. Catalyst with high-effectiveness and low-cost is a pivotal parameter determining the reliability and availability of this strategy. Herein, bifunctional graphitic carbon nitride/hydroxyapatite heterostructures (g-C3N4/HAP) were developed for indoor HCHO removal at ambient temperature. The optimal catalyst (g-C3N4/HAP-20) displayed enhanced HCHO removal efficiency of 36.6% and conversion (into CO2) efficiency of 28.4% within 2 h, compared with g-C3N4 (18.0% and 24.0%) and HAP (36.2% and ∼ 0%). Indoor fluorescent light accelerated HCHO elimination and its subsequent decomposition into CO2 over g-C3N4/HAP-20, delivering a HCHO removal efficiency of 82.7% and conversion efficiency of 100% within 2 h. Various characterizations and theoretical calculation reveal that g-C3N4/HAP possessed superoxide radicals and unpair electrons which were responsible for HCHO removal at ambient temperature; and a S-scheme heterostructure remarkably benefited the charge transfer and the photogenerated carriers’ separation, and consequently upgraded HCHO catalytic oxidation under indoor fluorescent-light illumination. This work offers a potent way to construct noble-metal free advanced catalysts with multi-functionality for indoor pollutant purification.

Regulating the electronic structure of Ir single atoms by ZrO2 nanoparticles for enhanced catalytic oxidation of formaldehyde at room temperature

Developing low-loading single-atom catalysts with superior catalytic activity and selectivity in formaldehyde (HCHO) oxidation at room temperature remains challenging. Herein, ZrO2 nanoparticles coupled low-loading Ir single atoms in N-doped carbon (Ir1-N-C/ZrO2) was prepared. The optimal Ir1-N-C/ZrO2 with 0.25 wt% Ir loading delivers the high HCHO removal and conversion efficiency (>95%) at 20 °C, which is higher than that over Ir1-N-C with the same Ir loading. The specific rate can reach 1285.6 mmol gIr−1 h−1, surpassing the Ir based catalysts reported to date. Density functional theory calculation results and electron spin resonance spectra indicate that the introduction of ZrO2 nanoparticles modulate the electronic structure of the Ir single atoms, promoting O2 activation to •O2–. Moreover, the Ir-C-Zr channel is favorable for the dissociation of •O2– to active oxygen atom (*O), and further accelerates the transformation of HCHO and intermediates (dioxymethylene and formates) to CO2 and H2O. This work provides a facile strategy to design low-loading single-atom catalysts with high catalytic activity toward HCHO oxidation.

Decahedral BiVO4/tubular g-C3N4 S-scheme heterojunction photocatalyst for formaldehyde removal: Charge transfer pathway and deactivation mechanism

Designing a durable and efficient heterojunction photocatalyst for the removal of indoor air pollutants has attracted significant attentions. However, the interfacial charge transfer pathway and deactivation mechanism of photocatalysts are still challenges. In this study, the decahedral BiVO4/tubular g-C3N4 (BiVO4/TCN) S-scheme heterojunction photocatalyst was synthesized, which exhibited excellent photocatalytic activity and stability for the removal of formaldehyde (HCHO) in a continuous-flow reactor. The formation of the S-scheme heterojunction promoted spatial separation of charges, enhanced the redox capability, and maintained favorable charge carrier potentials. Based on Central Composite Design, a semi-empirical equation was successfully established to predict the removal efficiency of HCHO, and photocatalyst load and initial concentration played important roles in the removal of HCHO. The interfacial charge transfer pathway in the S-scheme heterojunction was clearly confirmed through photo-irradiated Kelvin probe and in situ irradiated X-ray photoelectron spectroscopy analysis. The superficial state changes of BiVO4/TCN before and after the reaction indicated that the formation of coke could inhibit separation and transfer of electron-hole pairs, resulting in a slight decrease in photocatalytic activity. In summary, this study not only presents an effective technology for constructing S-scheme heterojunction photocatalyst, but also offers a new insight on the deactivation mechanism of photocatalyst during removal of volatile organic compounds.

Excellent Performance and Feasible Mechanism of ErOx-Boosted MnOx-Modified Biochars Derived from Sewage Sludge and Rice Straw for Formaldehyde Elimination: In Situ DRIFTS and DFT

To avoid resource waste and environmental pollution, a chain of ErOx-boosted MnOx-modified biochars derived from rice straw and sewage sludge (EryMn1-y/BACs, where biochars derived from rice straw and sewage sludge were defined as BACs) were manufactured for formaldehyde (HCHO) elimination. The optimal 15%Er0.5Mn0.5/BAC achieved a 97.2% HCHO removal efficiency at 220 °C and exhibited favorable EHCHO and thermal stability in a wide temperature window between 180 and 380 °C. The curbed influences of H2O and SO2 offset the boosting effect of O2 in a certain range. Er–Mn bimetallic-modified BACs offered a superior HCHO removal performance compared with that of BACs boosted using Er or Mn separately, owing to the synergistic effect of ErOx and MnOx conducive to improving the samples’ total pore volume and surface area, surface active oxygen species, promoting redox ability, and inhibiting the crystallization of MnOx. Moreover, the support’s hierarchical porous structure not only expedited the diffusion and mass transfer of reactants and their products but also elevated the approachability of adsorption and catalytic sites. Notably, these prominent features were partly responsible for the outstanding performance and excellent tolerance to H2O and SO2. Using in situ DRIFTS characterization analysis, it could be inferred that the removal process of HCHO was HCHOad → dioxymethylene (DOM) → formate species → CO2 + H2O, further enhanced with reactive oxygen species. The DFT calculation once again proved the removal process of HCHO and the strengthening effect of Er doping. Furthermore, the optimal catalytic performance of 15%Er0.5Mn0.5/BAC demonstrated its vast potential for practical applications.

Surface Structure Analysis and Formaldehyde Removal Mechanism of Lotus Shell Biochar: An Experimental and Theoretical Perspective.

The adsorption of gaseous HCHO by raw lotus shell biochar carbonized at 500, 700, and 900 °C from the perspective of its internal crystal structure and surface functional groups was investigated by an integrated approach of experiments and density functional theory calculations. The results showed that lotus shell biochar carbonized at 700 °C had the best adsorption effect at a HCHO concentration of 10.50 ± 0.30 mg/m3, with an adsorption removal rate of 87.64%. The HCHO removal efficiency by lotus shell biochar carbonized at 500 and 900 °C was determined to be 80.96 and 83.07%, respectively. The HCHO adsorption on lotus shell biochar carbonized at 700 °C conformed to pseudo-second-order kinetics and was predominantly controlled by chemical adsorption. The Langmuir isotherm was the underlying mechanism for the monomolecular layer adsorption with a maximum adsorption capacity of 0.329 mg/g. The density functional theory calculations revealed that the adsorption of HCHO on the surface of CaCO3 and KCl in lotus shell biochar carbonized at 700 °C was a chemical adsorption process, with adsorption energies ranging from -64.375 to -87.554 kJ/mol. The strong interaction between HCHO and the surface was attributed to the electron transfer from HCHO to the surface, facilitated by metal atoms (Ca or K) and the oxygen atoms of HCHO. The carboxyl group on the surface of lotus shell biochar carbonized at 700 °C was identified as the key functional group responsible for HCHO adsorption. This study advanced our understanding of the environmental functions of inorganic crystals and surface functional groups in raw biochar and will enable the further development of biochar materials in environmental applications.

Core-dual-shell structure MnO2@Co–C@SiO2 nanofiber membrane for efficient indoor air cleaning

Developing cost-effective and high-efficient air purification materials for enhancing the indoor air quality has been an ongoing concern. Herein, MnO2/Co–C catalyst layers were wrapped on SiO2 nanofiber by a combination of thermal pyrolysis and redox reaction method to prepare catalytic membranes (MCCS-x) for the efficient purification of indoor PM and HCHO. The core-dual-shell structure maintains the pore structure of the membrane, providing high gas permeability of 670 m3·m−2·h−1·kPa−1. Owing to the introduction of MnO2/Co–C enhanced the capture of PM, the optimized MCCS-2 exhibits high filtration efficiency of PM0.3 and PM2.5 (99.60% and 99.99%) with a low pressure drop (<80 Pa). In addition, MCCS-2 achieves 100% HCHO removal efficiency at room temperature due to its large specific surface area, high redox property and abundant Mn4+ and oxygen species. The appropriate proportion of Mn/Co bimetallic sites synergy inhibits the formation of formate and carbonate intermediate species, thus MCCS-2 possesses excellent long-term catalytic stability than contrast sample (MCCS-3 and MS). This work demonstrates a new approach for the fabrication of high-performance catalytic membrane materials for indoor air purification.

Amino groups modified MnOx‐PUF applied in indoor air purification: removing formaldehyde at room temperature

AbstractIndoor formaldehyde (HCHO) pollution has more and more serious adverse effects on human health, it is urgent to develop a material that can be embedded in the air purifier to achieve HCHO's degradation efficiently. In this work, based on the carrier material of polyurethane foam (PUF) modified by amino groups diethanolamine (DEA), we propose a strategy to prepare a manganese oxide compound catalyst (DEA‐MnOx‐PUF). During the static testing (CHCHO: 11.591 ppm, T: 25 °C), the catalyst shows higher HCHO removal efficiency (93.9 %) than that of unmodified MnOx‐PUF catalyst (88.6 %), and it achieves high HCHO‐to‐CO2 conversion (68.5 %). Additionally, during the continuous single‐pass catalysis testing (CHCHO: 11.591 ppm, T: 25 °C, 240000 mL/(gcath)), HCHO removal efficiency can be maintained around at 95 % within 50 hours. The excellent performance is attributed to the continuous decomposition of intermediates during the catalytic process by amino groups cross‐linked on the surface of the catalyst. Based on the block whole MnOx‐based catalyst DEA‐MnOx‐PUF, this work will provide a new route to develop a powerful purifier material with long‐term efficient removal of HCHO.

Efficient photothermal conversion for oxidation removal of formaldehyde using an rGO-CeO2 modified nickel foam monolithic catalyst

Photocatalysis is a feasible method for degrading indoor formaldehyde (HCHO) pollutants. To improve the purification efficiency and lower the cost of using noble metals as the primary component of the catalyst, synergistic catalysis involving two catalytic modes, such as thermocatalysis/photocatalysis, has attracted significant attention. In this study, a monolithic catalyst was prepared by loading reduced graphene oxide (rGO) and cerium dioxide (CeO2) on a nickel foam (NF) matrix. It was observed that the HCHO removal efficiency could be > 93 % under xenon light. The pre-deposited rGO on the NF matrix served as the photothermal conversion layer and contributed to the uniform and stable loading of CeO2. The surface temperature of this synthesized monolithic catalyst could rapidly rise to 170 °C. In addition, the heat was distributed evenly because of the increased near-infrared (NIR) light absorption caused by the added rGO and high electron mobility owing to the heat-conducting property of NF. At this temperature, the oxidation of HCHO was stimulated not only by the lattice oxygen of CeO2 but also by the production of O2– via oxidation by photogenerated electrons. In addition, O2– would reoxidize Ce3+ to Ce4+ on oxygen vacancies and accelerate the lattice oxygen consumption and supply cycle to reinforce the existing Mars-van Krevelen (MvK) mechanism.

Bimetallic oxide Cu2O@MnO2 with exposed phase interfaces for dual-effect purification of indoor formaldehyde and pathogenic bacteria.

The combination of materials with different functions is an optimal strategy for synchronously removing various indoor pollutants. For multiphase composites, exposing all components and their phase interfaces fully to the reaction atmosphere is a critical problem that needs to be solved urgently. Here, a bimetallic oxide Cu2O@MnO2 with exposed phase interfaces was prepared by a surfactant-assisted two-step electrochemical method, which shows a composite structure of non-continuously dispersed Cu2O particles anchored on flower-like MnO2. Compared with the pure catalyst MnO2 and bacteriostatic agent Cu2O, Cu2O@MnO2 respectively shows superior dynamic formaldehyde (HCHO) removal efficiency (97.2% with a weight hourly space velocity of 120 000 mL g-1 h-1) and pathogen inactivation ability (the minimum inhibitory concentration for 104 CFU mL-1 Staphylococcus aureus is 10 μg mL-1). According to material characterization and theoretical calculation, its excellent catalytic-oxidative activity is attributable to the electron-rich region at the phase interface which is fully exposed to the reaction atmosphere, inducing the capture and activation of O2 on the material surface, and then promoting the generation of reactive oxygen species that can be used for the oxidative-removal of HCHO and bacteria. Additionally, as a photocatalytic semiconductor, Cu2O further enhances the catalytic ability of Cu2O@MnO2 under the assistance of visible light. This work will provide efficient theoretical guidance and a practical basis for the ingenious construction of multiphase coexisting composites in the field of multi-functional indoor pollutant purification strategies.

Catalytic oxidation of formaldehyde on ultrathin Co3O4 nanosheets at room temperature: Effect of enhanced active sites exposure on reaction path

This research precisely controlled the thickness of Co3O4 nanosheets to investigate the effect of active sites exposure on the reaction path of HCHO catalytic oxidation. X-ray absorption fine structure demonstrates that ultrathin Co3O4 nanosheets (Co3O4-2) with atomic layer thickness (~2 nm) exhibit stronger lattice disorder than Co3O4 nanosheets with a thickness of 20 nm (Co3O4-20). Aberration-corrected scanning transmission electron microscopy confirms that two-dimensional structure and disordered structure of Co3O4-2 enhances the surface exposure of active sites (Co3+ and oxygen vacancies). Therefore, Co3O4-2 can produce more reactive oxygen species, avoiding the side reaction path dominated by undesired intermediates over Co3O4-20, where active sites are blocked and HCHO oxidation is inhibited. Consequently, the HCHO removal efficiency (＞90%) and CO2 conversion efficiency (＞90%) of Co3O4-2 are substantially higher than thicker Co3O4 nanosheets. This research provides an effective strategy to construct active sites and deep insights into the reaction path.

In situ growth of MnO2 on pDA-templated cotton fabric for degradation of formaldehyde

Degradation of formaldehyde (HCHO) in interior decoration has been an urgent issue due to its toxicity nature and potential threats to human health. In this work, manganese dioxide nanoparticles (MnO2 NPs) were in situ grown on the polydopamine (pDA)-templated cotton fabrics for environmentally friendly HCHO degradation applications. The morphology, elemental composition, and crystal structure of the cotton/pDA/MnO2 were characterized by scanning electron microscopy–energy dispersive X-ray spectrum, Fourier transform infrared, X-ray diffractometer and X-ray photoelectron spectroscopy, respectively. The degradation of HCHO by the as-developed cotton/pDA/MnO2 was measured in a self-made quartz reactor, and the stability of adsorption was evaluated by cyclic experiments. The results showed that the HCHO removal efficiency reached to 100% within 20 min after three cycles, suggesting that the as-prepared fabrics exhibited good stability for the degradation of HCHO. The development of MnO2 NPs coated fabrics provides new strategies in degradation HCHO in interior decoration.

Novel B and N Sites of One-Dimensional Boron Nitride Fiber: Efficient Performance and Mechanism in the Formaldehyde Capture Process.

Identification of adsorption centers with atomic levels of adsorbents is crucial to study the adsorption of formaldehyde (HCHO), especially for an in-depth understanding of the mechanism of HCHO capture. Herein, we investigate the HCHO adsorption performance of one-dimensional (1D) nanoporous boron nitride (BN) fiber, and explore the adsorption mechanism by density functional theory (DFT) calculations, including adsorption energy change and Bader charge change, and experimental study as well. Research shows that the 1D nanoporous BN fiber possesses a high concentration of Lewis pairs, which act as Lewis acid and Lewis base sites associated with the fiber’s electron-deficient and electron-rich features. It is worth noting that the HCHO removal efficiency of a typical sample is as high as 91%. This work may open the door to the field of adsorption of other pollutants by constructing Lewis pairs in the future.

Efficient Photothermal Elimination of Formaldehyde under Visible Light at Room Temperature by a MnOx-Modified Multi-Porous Carbon Sphere.

Volatile organic compounds (VOCs) exert a serious impact on the environment and human health. The development of new technologies for the elimination of VOCs, especially those from non-industrial emission sources, such as indoor air pollution and other low-concentration VOCs exhaust gases, is essential for improving environmental quality and human health. In this study, a monolithic photothermocatalyst was prepared by stabilizing manganese oxide on multi-porous carbon spheres to facilitate the elimination of formaldehyde (HCHO). This catalyst exhibited excellent photothermal synergistic performance. Therefore, by harvesting only visible light, the catalyst could spontaneously heat up its surface to achieve a thermal catalytic oxidation state suitable for eliminating HCHO. We found that the surface temperature of the catalyst could reach to up 93.8 °C under visible light, achieving an 87.5% HCHO removal efficiency when the initial concentration of HCHO was 160 ppm. The microporous structure on the surface of the carbon spheres not only increased the specific surface area and loading capacity of manganese oxide but also increased their photothermal efficiency, allowing them to reach a temperature high enough for MnOx to overcome the activation energy required for HCHO oxidation. The relevant catalyst characteristics were analyzed using XRD, measurement of BET surface area, scanning electron microscopy, HR-TEM, XPS, and DRS. Results obtained from a cyclic performance test indicated high stability and potential application of the MnOx-modified multi-porous carbon sphere.

Engineered graphite carbon nitride for efficient elimination of indoor formaldehyde at ambient temperature

Noble-metal-free graphitic carbon nitride (g-C3N4) with a tunable bandgap has evoked great interest as a robust and efficient catalyst for environmental remediation. Herein, we prepared g-C3N4-w with good water-dispersibility via a eutectic NaCl/KCl-assisted thermal polycondensation of dicyandiamide followed by sonication-exfoliation and water-washing processes. G-C3N4-w possesses a superior performance of formaldehyde (HCHO) removal at ambient temperature to the pristine g-C3N4 obtained via direct calcination of dicyandiamide. Indoor fluorescent-lamp irradiation further upgrades the catalytic decomposition of HCHO for the g-C3N4 samples, especially for g-C3N4-w. The HCHO removal efficiency for 180 min is 66.4% and 38.5% under indoor fluorescent lamp irradiation, and 37.1% and 14.2% without light illumination for g-C3N4-w and g-C3N4, respectively. The intriguing HCHO removal capability of g-C3N4-w is contributed by its large specific surface area, abundance of defects, rapid charge transfer and extending visible-light response.

Ti-modification enhanced the activity of flexible mesh-type Mn/γ-Al2O3/Al catalyst for indoor HCHO removal under humid conditions

Nowadays, MnO2-based catalysts have been widely applied in environmental fields, especially the removal of HCHO at room temperature. However, the moisture resistance of the catalyst is still a challenge. In this study, a series of MnTix/γ-Al2O3/Al catalysts were prepared by the methods of redox precipitation and impregnation, which showed excellent HCHO removal efficiency under humid conditions. When the catalyst accumulatively treated ca. 25 ppm of HCHO, there was still a HCHO conversion of 87.5% and the activity can be restored by washing and drying. DFT calculations, XPS, and TG results showed that Ti-modification could inhibit the adsorption of physisorbed water on the catalyst surface, thereby weakening the competitive adsorption between H2O and HCHO. This study provides a feasible strategy for the removal of HCHO under humid conditions.

Communication—Hollow MnO x @Nanoparticles Electrospun Fibers with High Porosity for Formaldehyde Removal at Room Temperature

MnO x nanomaterials are regarded as promising catalysts for degrading formaldehyde (HCHO). However, the catalytic nanoparticles (NPs) suffer from the catalysis performance and stability loss due to their weak combination with the substrates and easy-aggregation nature. Herein, we develop a facile method to synthesize hollow porous MnO x @NPs fibers via electrospinning and two-step oxidation. The NPs, e.g., TiO2 and SnO2, can be efficiently loaded into MnO x fibers’ inner frame through a simple dispersion process. The hollow porous structures obtained through two-step oxidation increase the HCHO removal efficiency by 8 times, while MnO x @SnO2 fibers exhibit the enhanced catalytic performance by 23.0% more.