Bio-Phenolic Resin Derived Porous Carbon Materials for High-Performance Lithium-Ion Capacitor

Recent Advances in Functionalized Biomass-Derived Porous Carbons and their Composites for Hybrid Ion Capacitors

Hybrid ion capacitors (HICs) have aroused extreme interest due to their combined characteristics of energy and power densities. The performance of HICs lies hidden in the electrode materials used for the construction of battery and supercapacitor components. The hunt is always on to locate the best material in terms of cost-effectiveness and overall optimized performance characteristics. Functionalized biomass-derived porous carbons (FBPCs) possess exquisite features including easy synthesis, wide availability, high surface area, large pore volume, tunable pore size, surface functional groups, a wide range of morphologies, and high thermal and chemical stability. FBPCs have found immense use as cathode, anode and dual electrode materials for HICs in the recent literature. The current review is designed around two main concepts which include the synthesis and properties of FBPCs followed by their utilization in various types of HICs. Among monovalent HICs, lithium, sodium, and potassium, are given comprehensive attention, whereas zinc is the only multivalent HIC that is focused upon due to corresponding literature availability. Special attention is also provided to the critical factors that govern the performance of HICs. The review concludes by providing feasible directions for future research in various aspects of FBPCs and their utilization in HICs.

Sulfate-reducing bacteria (SRB) mediated carbonate dissolution and arsenic release: Behavior and mechanisms

Carbonate bound arsenic act as an important reservoir for arsenic (As) in nature aquifers. Sulfate-reducing bacteria (SRB), one of the dominant bacterial species in reductive groundwater, profoundly affects the biogeochemical cycling of As. However, whether and how SRB act on the migration and transformation of carbonate bound arsenic remains to be elucidated. Batch culture experiment was employed using filed collected arsenic bearing calcite to investigate the release and species transformation of As by SRB. We found that arsenic in the carbonate samples mostly exist as inorganic As(V) (93.92 %) and As(III). The present of SRB significantly facilitated arsenic release from carbonates with a maximum of 22.3 μg/L. The main release mechanisms of As by SRB include 1) calcite dissolution and the liberate of arsenic in calcite lattices, and 2) the break of H-bonds frees arsenic absorbed on carbonate surface. A redistribution of arsenic during culture incubation took place which may due to the precipitation of As2Sx or secondary FeAl minerals. To our best knowledge, it is the first experimental study focusing on the release of carbonate bound arsenic by SRB. This study provides new insights into the fate and transport of arsenic mediated by microorganism within high arsenic groundwater-sediment system.

Fe2O3 Embedded in N-Doped Porous Carbon Derived from Hemin Loaded on Active Carbon for Supercapacitors

The high power density and long cyclic stability of N-doped carbon make it an attractive material for supercapacitor electrodes. Nevertheless, its low energy density limits its practical application. To solve the above issues, Fe2O3 embedded in N-doped porous carbon (Fe2O3/N-PC) was designed by pyrolyzing Hemin/activated carbon (Hemin/AC) composites. A porous structure allows rapid diffusion of electrons and ions during charge-discharge due to its large surface area and conductive channels. The redox reactions of Fe2O3 particles and N heteroatoms contribute to pseudocapacitance, which greatly enhances the supercapacitive performance. Fe2O3/N-PC showed a superior capacitance of 290.3 F g-1 at 1 A g-1 with 93.1% capacity retention after 10,000 charge-discharge cycles. Eventually, a high energy density of 37.6 Wh kg-1 at a power density of 1.6 kW kg-1 could be delivered with a solid symmetric device.