Ag-promoted Cr/MnO2 catalyst for catalytic oxidation of low-concentration formaldehyde at room temperature.

As one of the significant pollutants in indoor air, formaldehyde (HCHO) has attracted increasing attention due to its negative effects on human health. Thus, to reduce formaldehyde pollution, herein, an Ag-promoted Cr/MnO2 catalyst (Ag/Cr/MnO2) was obtained via a hydrothermal-calcination method, which was employed for the catalytic oxidation of low-concentration indoor HCHO (∼1 ppm) at room temperature. The Ag/Cr/MnO2 catalyst eliminated approximately 98.62% HCHO within 14 h and maintained a high removal efficiency continuously under the dynamic test conditions. Furthermore, the catalyst exhibited good recycling stability and outstanding activity in a humid environment. Different characterization techniques were utilized to determine the physicochemical properties that contribute to improving the catalytic performance. The Ag substance contained metallic Ag (Ag0) as the main component and some Ag2O, and the Ag0 particles provided ample active sites for the catalytic oxidation of HCHO. Besides, the incorporation of Ag increased the reducibility of the catalyst and the content of Mn4+, Cr6+ and oxygen vacancies. The abundant active sites, high reducibility, rich Mn4+, Cr6+, oxygen vacancies, and surface lattice oxygen species, and the powerful interaction between Cr/MnO2 and Ag were the reasons for the splendid catalytic capability for HCHO by the Ag/Cr/MnO2 catalyst. In conclusion, the Ag/Cr/MnO2 catalyst can be a promising catalyst to degrade HCHO with practical application significance.

Research on the elimination of low-concentration formaldehyde by Ag loaded onto Mn/CeO2 catalyst at room temperature.

Formaldehyde (HCHO) is one of the major air pollutants, and its effective removal at room temperature has proven to be a great challenge. In this study, an Ag/Mn/CeO2 catalyst for the catalytic oxidation of low-concentration HCHO at room temperature was prepared by a hydrothermal-calcination method. The removal performance of the Ag/Mn/CeO2 catalyst for HCHO was systematically studied, and its surface chemical properties and microstructure were analyzed. The incorporation of Ag did not change the mesoporous structure of the Mn/CeO2 catalyst but reduced the pore size and specific surface area. The Ag species included metallic Ag as the main component and part of Ag+. The well-dispersed Ag species on the catalyst provided sufficient active sites for the catalytic oxidation of HCHO. The more the Ag active sites, the more the lattice defects and oxygen vacancies generated from the interaction of Ag with Mn/CeO2. Precisely because of this, the Ag/Mn/CeO2 catalyst exhibited high catalytic activity for HCHO at room temperature with a removal efficiency of 96.76% within 22 h, which is 22.91% higher than that of the Mn/CeO2 catalyst. Moreover, the Ag/Mn/CeO2 catalyst showed good cycling stability and the removal efficiency reached 85.77% after five cycles. Therefore, the as-prepared catalyst is an effective and sustainable material that can be used to remove HCHO from actual indoor polluted air. This paper provides ideas for the research and development of efficient catalysts.

Adsorptivity and kinetics for low concentration of gaseous formaldehyde on bamboo-based activated carbon loaded with ammonium acetate particles.

The highly promising formaldehyde (HCHO)-removing materials are essential for eliminating interior pollution to safeguard the public's health with increasing indoor HCHO contamination situations being recorded on a global scale. In the paper, bamboo charcoal (BC) was activated with boric acid to prepare bamboo-based activated carbon (BAC), and then impregnated with ammonium acetate solution to successfully develop porous adsorbent with ammonium acetate particles (N/BAC), which was applied to remove low concentration of HCHO at room temperature. The adsorption performance for HCHO was systematically investigated while the surface chemical properties and microstructure of the as-prepared adsorbents were described and analyzed. The specific surface area, total pore volume and microporous volume of N/BAC sample were 240.09 m2/g, 0.27 cm3/g and 0.12 cm3/g, which increased by 42.40 m2/g, 0.15 cm3/g and 0.03 cm3/g compared with BAC sample, respectively. The specific surface area and the microporous volume, as well as the content of oxygen- and nitrogen-containing functional groups of N/BAC sample were augmented by contrast with other samples, and numerous ammonium acetate particles were present on the surface. Precisely because of this, the N/BAC sample exhibited a high removal rate of 98.89%, which was 18.38% greater than that of BAC sample. A superior correlation coefficient (0.9999) from the experimental values of the kinetics and the fitted values of the pseudo-second-order kinetic model demonstrated that the adsorption process of HCHO on N/BAC sample was physical-chemical combined adsorption. The adsorption of HCHO on N/BAC sample was investigated under different humidity, and the results showed that the adsorbent yet had excellent adsorption capacity (87.93%) under RH 75%. Moreover, the N/BAC sample was renewable, and the removal rate still reached 82.81% after five cycles of regeneration. Therefore, the as-prepared adsorbent is an effective, economical and sustainable material, and could be used to remove HCHO from real contaminated indoor air.

A Fluoride-Ion-Conducting Solid Electrolyte with Both High Conductivity and Excellent Electrochemical Stability.

Solid-state fluoride-ion batteries (FIBs) circumvent multiple formidable bottlenecks of lithium-ion batteries, but their overall performance remains inferior due to the absence of appropriate solid electrolytes. Presently the conductivity of most solid electrolytes for FIBs is too low to enable room-temperature cycling, while the few sufficiently conductive ones only allow for very low discharge voltages because of the narrow electrochemical stability window (ESW). Here, high room-temperature conductivity and a decent ESW are simultaneously achieved by designing a solid electrolyte CsPb0.9 K0.1 F2.9 . Its room-temperature conductivity is 1.23 × 10-3  S cm-1 , comparable to the most conductive system reported so far (PbSnF4 , 5.44 × 10-4 -1.6 × 10-3  S cm-1 ), but the ESW is several times broader. With these appealing characteristics simultaneously achieved in the solid electrolyte, a cell with much higher voltages than other room-temperature-operable solid-state FIBs in literature is successfully constructed, and stably cycled at 25 °C for 4581 h without considerable capacity fade.

Synthesis and characterization of CuxO/Bi2O3 oxides for removal of HCHO under visible light irradiation.

CuxO/Bi2O3 oxides grown on nickel foam were synthesized via an electrodeposition method to degrade indoor HCHO under visible light irradiation and fully characterized by XRD, SEM, FT-IR, and UV-Vis technologies. The characterization results showed that the CuxO/Bi2O3 oxides were successfully loaded on nickel foam and the visible light response spectrum was expanded to 740 nm. Plackett-Burman design combined with central composite design has been used to optimize factors that affect HCHO removal performance. The results demonstrated that bismuth nitrate content, polyethylene glycol 600 content, sintering time, and lactic acid concentration were the four most important factors affecting the HCHO removal performance over CuxO/Bi2O3 sample. The optimum CuxO/Bi2O3 sample could degrade 88.796% of HCHO in 300 min at the conditions of 4.28 mol/L lactic acid, 4.86% polyethylene glycol 600, 194.03 min sintering time, and 45.83 g bismuth nitrate, and the HCHO removal rate remained 82.3% after five cycles. A plausible mechanism for the degradation of HCHO under visible light irradiation was proposed. This work provides a feasible solution for removing indoor formaldehyde in the field of photocatalysis.

A cost-effective and humidity-tolerant chloride solid electrolyte for lithium batteries.

Li-ion-conducting chloride solid electrolytes receive considerable attention due to their physicochemical characteristics such as high ionic conductivity, deformability and oxidative stability. However, the raw materials are expensive, and large-scale use of this class of inorganic superionic conductors seems unlikely. Here, a cost-effective chloride solid electrolyte, Li2ZrCl6, is reported. Its raw materials are several orders of magnitude cheaper than those for the state-of-the-art chloride solid electrolytes, but high ionic conductivity (0.81 mS cm-1 at room temperature), deformability, and compatibility with 4V-class cathodes are still simultaneously achieved in Li2ZrCl6. Moreover, Li2ZrCl6 demonstrates a humidity tolerance with no sign of moisture uptake or conductivity degradation after exposure to an atmosphere with 5% relative humidity. By combining Li2ZrCl6 with the Li-In anode and the single-crystal LiNi0.8Mn0.1Co0.1O2 cathode, we report a room-temperature all-solid-state cell with a stable specific capacity of about 150 mAh g-1 for 200 cycles at 200 mA g-1.