Catalytic degradation of benzene at room temperature over FeN4O2 sites embedded in porous carbon.

Benzene and its aromatic derivatives are typical volatile organic compounds for indoor and outdoor air pollution, harmful to human health and the environment. It has been considered extremely difficult to break down benzene rings at ambient conditions without external energy input, due to the extraordinary stability of the aromatic structure. Here, we show one such solution that can thoroughly degrade benzene to basically water and carbon dioxide at 25 °C in air using atomically dispersed Fe in N-doped porous carbon, with almost 100% benzene conversion. Further experimental studies combined with molecular simulations reveal the mechanism of this catalytic reaction. Hydroxyl radicals (·OH) evolved on the atomically dispersed FeN4O2 catalytic centers were found responsible for initiating and completing the oxidation of benzene. This work provides a new chemistry to degrade aromatics at ambient conditions and also a pathway to generate active ·OH oxidant for generic remediation of organic pollutants.

Pt-Pd Nanoalloys Functionalized Mesoporous SnO2 Spheres: Tailored Synthesis, Sensing Mechanism, and Device Integration.

Methane (CH4 ), as the vital energy resource and industrial chemicals, is highly flammable and explosive for concentrations above the explosive limit, triggering potential risks to personal and production safety. Therefore, exploiting smart gas sensors for real-time monitoring of CH4 becomes extremely important. Herein, the Pt-Pd nanoalloy functionalized mesoporous SnO2 microspheres (Pt-Pd/SnO2 ) were synthesized, which show uniform diameter (≈500 nm), high surface area (40.9-56.5 m2 g-1 ), and large mesopore size (8.8-15.8 nm). The highly dispersed Pt-Pd nanoalloys are confined in the mesopores of SnO2 , causing the generation ofoxygen defects and increasing the carrier concentration of sensitive materials. The representative Pt1 -Pd4 /SnO2 exhibits superior CH4 sensing performance with ultrahigh response (Ra /Rg = 21.33 to 3000 ppm), fast response/recovery speed (4/9 s), as well as outstanding stability. Spectroscopic analyses imply that such an excellent CH4 sensing process involves the fast conversion of CH4 into formic acid and CO intermediates, and finally into CO2 . Density functional theory (DFT) calculations reveal that the attractive covalent bonding interaction and rapid electron transfer between the Pt-Pd nanoalloys and SnO2 support, dramatically promote the orbital hybridization of Pd4 sites and adsorbed CH4 molecules, enhancing the catalytic activation of CH4 over the sensing layer.

Engineering CSFe Bond Confinement Effect to Stabilize Metallic-Phase Sulfide for High Power Density Sodium-Ion Batteries.

Metallic-phase iron sulfide (e.g., Fe7 S8 ) is a promising candidate for high power density sodium storage anode due to the inherent metal electronic conductivity and unhindered sodium-ion diffusion kinetics. Nevertheless, long-cycle stability can not be achieved simultaneously while designing a fast-charging Fe7 S8 -based anode. Herein, Fe7 S8 encapsulated in carbon-sulfur bonds doped hollow carbon fibers (NHCFs-S-Fe7 S8 ) is designed and synthesized for sodium-ion storage. The NHCFs-S-Fe7 S8 including metallic-phase Fe7 S8 embrace higher electron specific conductivity, electrochemical reversibility, and fast sodium-ion diffusion. Moreover, the carbonaceous fibers with polar CSFe bonds of NHCFs-S-Fe7 S8 exhibit a fixed confinement effect for electrochemical conversion intermediates contributing to long cycle life. In conclusion, combined with theoretical study and experimental analysis, the multinomial optimized NHCFs-S-Fe7 S8 is demonstrated to integrate a suitable structure for higher capacity, fast charging, and longer cycle life. The full cell shows a power density of 1639.6 W kg-1 and an energy density of 204.5 Wh kg-1 , respectively, over 120 long cycles of stability at 1.1 A g-1 . The underlying mechanism of metal sulfide structure engineering is revealed by in-depth analysis, which provides constructive guidance for designing the next generation of durable high-power density sodium storage anodes.

Complete and rapid degradation of glyphosate with Fe3Ce1Ox catalyst for peroxymonosulfate activation at room temperature.

Glyphosate, a common broad-spectrum herbicide, is a serious environmental pollutant that causes a significant threat to humans. Hence, there is a pressing task to remove glyphosate from the environment. Here, we report an excellent Fe3Ce1Ox catalyst synthesized via the one-step co-precipitation method for activating peroxymonosulfate (PMS) to degrade glyphosate at 25 °C. As a result, glyphosate is completely degraded with a high degradation rate of 400 mg L-1·h-1, and the TOC and TN removals are 85.6% and 80.8%, respectively. As proven by systematic characterizations, the Fe-Ce synergistic effect plays a significant role in promoting PMS activation. The main reactive oxygen species for glyphosate oxidation are surface-bound SO4-· and ·OH, produced by activating PMS by electron transfer between Fe2+/Fe3+ and Ce3+/Ce4+ of Fe3Ce1Ox. In light of the products determined, the possible degradation process of glyphosate is also speculated: C-N and C-P bonds of glyphosate molecules are attacked to form aminomethylphosphonic acid (AMPA) and orthophosphate (PO43-) by surface-bound SO4-· and ·OH that continuously mineralize and dephosphorylate AMPA to generate small molecules and inorganic ions, such as H2O and PO43-. The results of this work suggest that Fe3Ce1Ox/PMS could provide a potential candidate for efficiently removing organic compounds containing nitrogen or phosphorus from wastewater.