Sodium ion batteries (SIBs) using hard carbon as negative electrode hold the promise of being low cost alternative to lithium ion batteries (LiBs). However, the Na + storage mechanism in hard carbons is not fully understood yet and the attribution of Na storage in the sloping and plateau regions of the sodiation/desodiation curves remains still controversial. The current work employs N 2 , Kr and CO 2 gases to correctly assess the changes in hard carbon porosity induced by different pyrolysis temperature of cellulose. The sloping capacity was found to decrease with the decrease of the specific area of ultramicropores measurable only by CO 2 adsorption, while the plateau capacity demonstrated an opposite behavior. The high temperature derived carbons (> 1400°C) present no porosity which disqualifies the attribution of plateau region to the adsorption of Na + in the nanopores but rather the insertion between the pseudo-graphitic domains. Temperature programmed desorption coupled with mass spectrometry (TPD-MS) was performed to determine the nature and the quantity of oxygen surface functional groups followed by oxygen chemisorptions to assess the amount of carbon edge defects expressed by active surface area (ASA) values. A decrease in the amount of oxygen groups and active surface area with the increase of the pyrolysis temperature was observed which is accompanied by a decrease of the sloping capacity. These results shed light in the storage mechanisms, the sloping region being ascribed mainly to the interaction of Na + with carbon edge defects and adsorption in the microporosity while the plateau region assigned to the intercalation of Na + in the pseudo-graphitic nanodomains.

Extracting uranium from seawater is challenging due to its low concentration (3.3 ppb) and the myriad of competing ions. Mesoporous carbon materials provide a high surface area alternative to the traditional polymeric fiber braids developed for seawater extractions, specifically uranium extraction. In this work, sonochemical grafting of acrylonitrile onto the pores of soft-templated mesoporous carbons followed by its conversion to amidoxime functionalities was used to prepare an effective sorbent material with a high density of binding sites. Pore blockage, often observed for free radical polymerization, leads to poor adsorbent performance but can be easily overcome by the use of ultrasound during polymerization.Parameters such as surface area and surface pre-treatment, sonication intensity, solvent system, and monomer/initiator ratios were varied to optimize the polymerization and uranium adsorption capacity while not blocking the porosity, a significant hurdle in the utilization of functionalized porous materials.The results show that neither the surface oxidation with nitric acid nor CO 2 activation alone is sufficient to cause significant improvement in grafting and uranium uptake. However, when coupled together, a greatly enhanced performance of the adsorbent materials was observed.

Amidoxime-modified ordered mesoporous silica (OMS) materials were prepared by co-condensation synthesis of OMS with cyanopropyl groups followed by their conversion into amidoxime groups, and tested for uranium adsorption under seawater conditions.