RESUMEN
Preparation of superhydrophobic carbon materials from lignocellulosic biomass waste via one-step carbonization is very difficult due to the existences of polar functional groups and ashes, which are extremely hydrophilic. Herein, superhydrophobic carbon materials can be facilely synthesized by catalytic pyrolysis of biomass waste using FeCl3 as catalyst. The results show that the surface energy of lignin-derived char (CharL) is significantly reduced to 19.25 mN m-1 from 73.29 mN m-1, and the water contact angle increased from 0 to 151.5°, by interaction with FeCl3. Multiple characterizations and control experiments demonstrate that FeCl3 can catalyze the pyrolytic volatiles to form a rough graphite and diamond-like carbon layer that isolates the polar functional groups and ashes on CharL, contributing to the superhydrophobicity of the CharL. The one-step catalytic pyrolysis is able to convert different natural biomass waste (e.g., lignin, cellulose, sawdust, rice husk, maize straw, and pomelo peel) into superhydrophobic carbon materials. This study contributes new information related to the interfacial chemistry during the sustainable utilization of biomass waste.
RESUMEN
Synergistic improvements in the electrical conductivity and catalytic activity for the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) are of paramount importance for rechargeable metal-air batteries. In this study, one-nanometer-scale ultrathin cobalt oxide (CoOx ) layers are fabricated on a conducting substrate (i.e., a metallic Co/N-doped graphene substrate) to achieve superior bifunctional activity in both the ORR and OER and ultrahigh output power for flexible Zn-air batteries. Specifically, at the atomic scale, the ultrathin CoOx layers effectively accelerate electron conduction and provide abundant active sites. X-ray absorption spectroscopy reveals that the metallic Co/N-doped graphene substrate contributes to electron transfer toward the ultrathin CoOx layer, which is beneficial for the electrocatalytic process. The as-obtained electrocatalyst exhibits ultrahigh electrochemical activity with a positive half-wave potential of 0.896 V for ORR and a low overpotential of 370 mV at 10 mA cm-2 for OER. The flexible Zn-air battery built with this catalyst exhibits an ultrahigh specific power of 300 W gcat -1 , which is essential for portable devices. This work provides a new design pathway for electrocatalysts for high-performance rechargeable metal-air battery systems.
RESUMEN
Petroleum-contaminated soil (PCS) caused by the accidental release of crude oil into the environment, which occurs frequently during oil exploitation worldwide, needs efficient and cost-effective remediation. In this study, a fast pyrolysis technology was implemented to remediate the PCS and concurrently recover the oil. The remediation effect related to pyrolytic parameters, the recovery rate of oil and its possible formation pathway, and the physicochemical properties of the remediated PCS and its suitability for planting were systematically investigated. The results show that 50.9% carbon was recovered in oil, whose quality even exceeds that of crude oil. Both extractable total petroleum hydrocarbon (TPH) and water-soluble organic matter (SOM) in PCS were completely removed at 500 °C within 30 min. The remaining carbon in remediated PCS was determined to be in a stable and innocuous state, which has no adverse effect on wheat growth. On the basis of the systematically characterizations of initial PCS and pyrolytic products, a possible thermochemical mechanism was proposed which involves evaporation, cracking and polymerization. In addition, the energy consumption analysis and remediation effect of various PCSs indicate that fast pyrolysis is a viable and cost-effective method for PCS remediation.