Facile fabrication of WS2 nanocrystals confined in chlorella-derived N, P co-doped bio-carbon for sodium-ion batteries with ultra-long lifespan.

Sodium-ion batteries (SIBs) have been regarded as a promising substitute for lithium-ion batteries but there are still formidable challenges in developing an anode material with adequate lifespan and outstanding rate performance. Transition metal dichalcogenides (TMDs) are promising anode materials for SIBs due to their high theoretical capacities. However, their severe volume expansions and low electronic conductivity impede their practical developments. In addition, the synthesis of energy storage materials from waste biomass has aroused extensive attention. Herein, we synthesize WS2 nanocrystals embedded in N and P co-doped biochar via a facile bio-sorption followed by sulphurization, employing waste chlorella as the adsorbent and bio-reactor. The WS2 nanocrystals are beneficial for storing more sodium ions and expediting the transportation of sodium ions, thus improving the capacity and reaction kinetics. Chlorella acts as a reactor and not only inhibits the stacking of WS2 nanocrystals during the synthesis process but also alleviates the mechanical pressure of composite during the charge/discharge process. As a result, the WS2/NPC-2 electrode delivers a high specific capacity (436 mA h g-1 at 0.1 A g-1) and superior rate performance of 311 mA h g-1 at 3 A g-1 for SIBs. It also exhibits excellent stability even up to 6000 cycles at 5 A g-1, which is one of the optimal long-cycle properties reported for WS2-based materials to date.

In situ fabrication of ultrathin few-layered WSe2 anchored on N, P dual-doped carbon by bioreactor for half/full sodium/potassium-ion batteries with ultralong cycling lifespan.

Sodium/potassium-ion batteries (SIBs/PIBs) with high electrochemical performance are promising but there still remain daunting challenges to explore an anode material with appealing cycling stability and rate capability. In addition, the utilization of waste biomass arouses tremendous researches in energy storage applications. Herein, we elaborately coupling ultrathin few-layered WSe2 nanosheets with N, P-doped biochar by utilizing waste chlorella as adsorbent and reactor. It displays a prominent long-term cycling property (265 mAh g-1 at 1 A g-1 up to 1500 cycles) in SIBs, which is the best long-cycle performance ever reported for WSe2. Paired with Na3V2(PO4)3 cathode, full SIBs also exhibit superior capacity of 210 mAh g-1 at 0.5 A g-1 for 120 cycles. Notably, we also report WSe2-based anode material in PIBs, which delivers a high capacity of 333 mAh g-1 at 0.1 A g-1 for 100 cycles and superior cycling lifespan (155 mAh g-1 at 1 A g-1 up to 5300 cycles) as well as excellent rate properties. Additionally, the mechanism of the repeated process of sodiation/desodiation is revealed, by the deep characterization, such as ex-situ XRD/Raman, galvanostatic intermittent titration technique and CV measurements.

Facile Synthesis of Ultra-Small Few-Layer Nanostructured MoSe2 Embedded on N, P Co-Doped Bio-Carbon for High-Performance Half/Full Sodium-Ion and Potassium-Ion Batteries.

Sodium/potassium-ion batteries (SIBs/PIBs) arouse intensive interest on account of the natural abundance of sodium/potassium resources, the competitive cost and appropriate redox potential. Nevertheless, the huge challenge for SIBs/PIBs lies in the scarcity of an anode material with high capacity and stable structure, which are capable of accommodating large-size ions during cycling. Furthermore, using sustainable natural biomass to fabricate electrodes for energy storage applications is a hot topic. Herein, an ultra-small few-layer nanostructured MoSe2 embedded on N, P co-doped bio-carbon is reported, which is synthesized by using chlorella as the adsorbent and precursor. As a consequence, the MoSe2 /NP-C-2 composite represents exceedingly impressive electrochemical performance for both sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). It displays a promising reversible capacity (523 mAh g-1 at 100 mA g-1 after 100 cycles) and impressive long-term cycling performance (192 mAh g-1 at 5 A g-1 even after 1000 cycles) in SIBs, which are some of the best properties of MoSe2 -based anode materials for SIBs to date. To further probe the great potential applications, full SIBs pairing the MoSe2 /NP-C-2 composite anode with a Na3 V2 (PO4 )3 cathode also exhibits a satisfactory capacity of 215 mAh g-1 at 500 mA g-1 after 100 cycles. Moreover, it also delivers a decent reversible capacity of 131 mAh g-1 at 1 A g-1 even after 250 cycles for PIBs.

Production of citrinin-free Monascus pigments by submerged culture at low pH.

Microbial fermentation of citrinin-free Monascus pigments is of great interest to meet the demand of food safety. In the present work, the effect of various nitrogen sources, such as monosodium glutamate (MSG), cornmeal, (NH4)2SO4, and NaNO3, on Monascus fermentation was examined under different initial pH conditions. The composition of Monascus pigments and the final pH of fermentation broth after Monascus fermentation were determined. It was found that nitrogen source was directly related to the final pH and the final pH regulated the composition of Monascus pigments and the biosynthesis of citrinin. Thus, an ideal nitrogen source can be selected to control the final pH and then the citrinin biosynthesis. Citrinin-free orange pigments were produced at extremely low initial pH in the medium with (NH4)2SO4 or MSG as nitrogen source. No citrinin biosynthesis at extremely low pH was further confirmed by extractive fermentation of intracellular pigments in the nonionic surfactant Triton X-100 micelle aqueous solution. This is the first report about the production of citrinin-free Monascus pigments at extremely low pH.

Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation.

In this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product.