BT100, a three-in-one, multipurpose disinfecting, deodorizing, and air-cleaning solution with an effective, gradual, and continuous gaseous chlorine dioxide-releasing substance

Aerosols carrying viruses that are released from the oral cavity of infected individuals are the primary, if not the only, means of transmission during viral respiratory disease epidemics. This makes crowded rooms and tiny, enclosed public areas like bathrooms prime environments for the transmission of diseases. Volatile organic compounds (VOCs) and formaldehyde are two contaminants that pose serious threats to human health and well-being in indoor environments. The varied disinfectant properties of chlorine dioxide (ClO2) make it a key player in treating a range of air quality issues. To balance effectiveness and safety, however, the careful application of chlorine dioxide is essential to achieving the best results in air quality while preserving human health and well-being. This study explores the many functions of chlorine dioxide, including the prevention of the spread of viruses, the elimination of harmful gases like ammonia and hydrogen sulfide, and its effects on formaldehyde and total volatile organic compounds (TVOCs) in indoor environments using BT100. The results indicate a reduction of 98.5%, 81.01%, 62.22%, 46.5%, and 63.84% in minimizing aerosolized viruses, ammonia, and hydrogen sulfide gas in addition to formaldehyde and total volatile organic compounds.

Converting formaldehyde in methanol with MoO2 under irradiation: A pollution-free strategy for cleaning air

Direct photocatalytic reduction of toxic formaldehyde (HCHO) in value-added chemicals and fuels is promising because that not only abates the environmental pollution, but also solves the energy shortage. Herein, self-supported MoO2 and MoO3 nanoparticles growing on Mo meshes were comparatively applied to the photocatalytic conversion of HCHO. Under UV-visble lights, MoO2 reduces HCHO in methanol (CH3OH) while MoO3 oxidizes HCHO in carbon oxide and water. Their contrary photocatalytic capacities were revealed. Compared with MoO3, the lower work function of MoO2 enables an electron-rich interface, realizing a complete reduction of 30 ppm HCHO to CH3OH in 30 min. Theoretical calculations clarify that a large number of delocalized electrons on MoO2 attracts HCHO molecule and activates its CO bond, facilitating subsequent hydrogenation and reduction of HCHO to CH3OH. As for MoO3, the wider bandgap and higher potential of valence band govern the photocatalytic oxidation of HCHO.

Observation on the aerosol and ozone precursors in suburban areas of Shenzhen and analysis of potential source based on MAX-DOAS

Long-term stereoscopic observations of aerosol, NO₂, and HCHO were carried out at the Yangmeikeng (YMK) site in Shenzhen. Aerosol optical depths and NO₂ vertical column concentration (NO₂ VCD) derived from MAX-DOAS were found to be consistent with other datasets. The total NO₂ VCD values of the site remained low, varying from 2 × 10¹⁵ to 8 × 10¹⁵ mol/cm², while the HCHO VCD was higher than NO₂ VCD, varying from 7 × 10¹⁵ to 11 × 10¹⁵ mol/cm². HCHO VCD was higher from September to early November than that was from mid-late November to December and during February 2021, in contrast, NO₂ VCD did not change much during the same period. In January, NO₂ VCD and HCHO VCD were both fluctuating drastically. High temperature and HCHO level in the YMK site is not only driving the ozone production up but also may be driving up the ozone concentration as well, and the O₃ production regime in the YMK site tends to be NO_x-limited. At various altitudes, backward trajectory clustering analysis and Potential Source Contribution Function (PSCF) were utilized to identify possible NO₂ and HCHO source locations. The results suggested that the Huizhou-Shanwei border and the Daya Bay Sea area were the key potential source locations in the lower (200 m) and middle (500 m) atmosphere (WPSCF > 0.6). The WPSCF value was high at the 1000 m altitude which was closer to the YMK site than the near ground, indicating that the pollution transport capability in the upper atmosphere was limited.

High-efficient capture and degradation of formaldehyde based on the electric-field-enhanced catalytic effect

Enhancing the generation of active groups is of great significance for alleviating the catalyst deactivation of formaldehyde (HCHO) by accelerating the decomposition of intermediate products. Herein, an electric-field-enhanced catalytic effect was proposed for the efficient capture and degradation of HCHO base on carbon cloth loaded manganese oxide catalyst (MnO_x-CC). Under the action of electric field, MnO_x can generate more hydroxyl radicals (•OH) and superoxide radicals (•O₂^-), thus accelerating the degradation of HCHO and intermediates at room temperature. After the introduction electric field (∼1 ×10⁴ V/m), •O₂^- and •OH radical on the surface of MnO_x-CC catalyst can be increased by 8 times and 23 times, respectively. At weight hourly space velocity of 300,000 mL/(g_cat h) for ∼15 ppm HCHO, MnO_x-CC-Electric Field catalyst reached the removal efficiency of 99.4%, and the CO₂ conversion efficiency of 81.2%, without decrease significantly within 80 h. Theoretical calculation shows that the electric field can increase the electron state density of Mn atom at the Fermi level and reduce the adsorption energy of HCHO, O₂ and H₂O, thus promoting the generation of active groups and degradation of intermediate products. The electric-field-enhancement catalytic effect provides a new approach for the degradation of Volatile Organic Compounds.

Enhanced the synergistic degradation effect between active hydroxyl and reactive oxygen species for indoor formaldehyde based on platinum atoms modified MnOOH/MnO2 catalyst

Maintaining high activity during prolonged catalysis is always the pursuit in catalytic degradation of organic pollutants. For indoor formaldehyde (HCHO) degradation, the accumulation of intermediates is the major factor limiting the conversion of HCHO to final product CO₂ (HCHO-to-CO₂ conversion) and long-lasting catalysis. Herein, a three-dimensional radialized nanostructure catalyst self-assembled by MnOOH/MnO₂ nanosheets anchored with Pt single atoms (Pt_SA-MnOOH/MnO₂ with a trace platinum loading amount of 0.09%) is developed by thermally assisted two-step electrochemical method, which achieves enhanced CO₂ production in catalytic HCHO degradation at the room temperature by the collaborative action of active hydroxyl (OH*) and active oxygen species (O₂*). By boosting intermediates' decomposing, the catalyst implements real-time HCHO-to-CO₂ conversion (∼85.7%) and long-term continuous HCHO removal (∼98%) during 100 h in a 15 ppm HCHO atmosphere at 25 °C under a weight hourly space velocity of 30000 mL/g_cat∙h. Density functional theory calculation shows that the formation energy of O₂* from O₂ over Pt_SA-MnOOH/MnO₂ is nearly half lower than that over Pt-MnO₂ catalyst. And decomposing accumulated intermediates gives the credit to OH* species sustainably generated by the combined action of MnOOH and O₂*. The synergistic action between Pt_SA and MnOOH contributes to the continuous production of O₂* and OH* for enhancing CO₂ production in indoor catalytic formaldehyde degradation.

Enhanced photocatalytic performance of visible-light-driven CuOx/TiO2-x for degradation of gaseous formaldehyde: Roles of oxygen vacancies and nano copper oxides

Photocatalysis is an effective method for the removal of formaldehyde (HCHO), and high-efficiency visible-light-driven photocatalysts were urgently required. Herein, oxygen vacancies (OVs) and nano copper oxides (CuO_x) synergistically modified TiO₂ (CuO_x/TiO_2-x) photocatalysts were synthesized by one-step hydrothermal followed by impregnation method. The photocatalytic decomposition of HCHO reached 100% at initial concentration of 180 ppm under relative humidity (RH) = 60% by 0.1g CuO_x/TiO_2-x in 150 min visible light irradiation. Characterization results explored the complementary effect of OVs and CuO_x systematically. The OVs increased the separation efficiency of photogenerated charge carriers and act as adsorption/active sites in HCHO photocatalytic oxidation. The moisture and O₂ were adsorbed and actived by OVs to generate reactive oxygen species (ROS). After doped CuO_x on the surface of TiO_2-x, the photoexcited electrons in Cu₂O could transfer to the conduction band (CB) of TiO_2-x and the photoexcited electrons of TiO_2-x could be captured by Cu nanoparticles. Therefore, more ROS were generated due to the synergistic effect of OVs and CuO_x. The In-situ Fourier transform infrared (in-situ FTIR) measurements show the hydroxyl radical (•OH) was the dominant radical in HCHO photocatalytic oxidation, while •O₂^- could also upgrade the photodegradation efficiency of HCHO. Furthermore, the stability tests showed the degradation efficiency of HCHO still reached 90% after five recycles, indicating that CuO_x/TiO_2-x nanocomposites displayed a stable and high photoactivity in volatile organic compounds (VOCs) decomposition.

Mechanistic insights into the dehydrogenation of formaldehyde, formic acid and methanol using the Pt4 cluster as a promising catalyst

Reaction mechanisms of the dehydrogenation of formaldehyde, formic acid and methanol on the Pt₄ cluster were computationally investigated using density functional theory (DFT) with the B3LYP functional in the conjunction with the aug-cc-pVTZ basis sets for H, C and O atoms, and the cc-pVDZ-PP basis set for Pt. Herein, the key mechanistic aspects of three possible pathways of the dehydrogenation of these compounds are summarized. The results indicate that the formation of H₂ and CO or CO₂ molecules is more energetically favorable than the generation of H and H₂O, HCHO products. Generally, the formation of H₂ molecule in the presence of catalysts is more favorable than the direct decomposition of either HCHO, HCOOH or CH₃OH molecule. The use of Pt₄ catalyst significantly reduces the energy barriers for C-H and O-H bond cleavage of all three compounds to 14, 9 and 12 kcal/mol, respectively. The decomposition of HCOOH is found to be the most energetically favorable. In addition, the mechanistic insights of the reactions confirm the reduction of the energy barriers of the gas-phase dehydrogenation by 67-82 kcal/mol and bring it to the values smaller than 14 kcal/mol in the presence of the Pt₄ catalysts.