ZIF-8 derived ZnWO4 nanocrystals: Calcination temperature induced evolution of composition and microstructures, and their electrochemical performances as anode for lithium-ion batteries

Facile construction of ZnWO4/ZnO porous nanoplates on reduced graphene oxide for superior lithium storage

Zinc tungstate (ZnWO4) shows great promise as an anode material for lithium-ion batteries (LIBs) owing to its reversible multi-electron redox reactions and high theoretical capacity. Nevertheless, the low conductivity and big strain during cycling can lead to the inferior electrochemical properties of the ZnWO4 anode, hindering its practical application. Herein, we report a novel composite with ZnWO4/ZnO porous nanoplates in-situ constructed on reduced graphene oxide (rGO) by a metal-organic framework template strategy. The nanoplates with good porosity are composed of nanoparticles and nanorods, providing a short Li+-diffusion distance and plentiful Li+ storage active sites. The introduction of rGO can accelerate charge transfer and reinforce structural stability. As a result of these advantages, the ZnWO4/ZnO/rGO composite as LIBs anode delivers a high reversible capacity of 811 mAh g after 100 cycles at 200 mA g-1, excellent rate capability (437 mAh g at 5000 mA g-1), and good long cycling stability (485 mAh g after 500 cycles at 2000 mA g-1). Notably, the rate capability of the composite far precedes the previously reported ZnWO4-based anodes. This work provides an efficient approach for designing and fabricating advanced metal tungstate-based anodes for high-performance LIBs.

Effective adsorptive removal of sulfamethoxazole (SMX) from aqueous solution by ZIF-8 derived adsorbent ZC-0.5

Efficient removal of antibiotics from the aquatic environment is urgently needed due to their obstinate accumulation and non-biodegradability. In this study, a mesoporous carbon material (ZC-0.5) was successfully synthesized for the adsorption of sulfamethoxazole (SMX), one of the major antibiotics for the treatment of human and animal infections. ZIF-8 as the precursor of ZC-0.5, specifically, using cetyl trimethyl ammonium bromide (CTAB) and sodium laurate (SL) as dual templates and carbonizing at 800 ℃. This novel adsorbent exhibited a high proportion of mesopore (75.64%) and a large specific surface area (1459.73 m²·g^-1). The adsorption experiment examined the reusability of ZC-0.5 and that it could retain superior maximum adsorption capacities (167.45 mg∙L^-1) after five cycles of adsorption and desorption. The adsorption process satisfied the pseudo-second-order kinetic (PSO) and mixed first- and second-order kinetic (MOE). It also satisfied the Freundlich and Sips isotherm models. Moreover, thermodynamic calculation indicated the adsorption process was spontaneous, endothermal, and entropy-increasing. Furthermore, plausible adsorption mechanisms were explained through van der Waals force, electrostatic interaction, hydrophobic force, π-π interaction, and hydrogen bond. This work offers a new efficient adsorbent for antibiotic elimination.

One-pot thermal decomposition of commercial organometallic salt to Fe2O3@C-N and MnO@C-N for lithium storage

Iron oxide (Fe2O3) nanoparticles encapsulated in the N-doped carbon framework (Fe2O3@C-N) were synthesized via a one-step thermal decomposition reaction of commercial C10H12FeN2NaO8 (ethylenediaminetetraacetic acid monosodium ferric salt), which can serve as the source of Fe, O, C, and N. As an anode material for lithium storage, the Fe2O3@C-N sample exhibits a reversible capacity of 1072 mA h g-1 after 200 cycles at 0.2 A g-1 and 553 mA h g-1 after 500 cycles at 0.5 A g-1. Furthermore, the synthetic strategy can be simply extended to prepare other similar products, e.g. MnO@C-N and ZnO@C-N. The MnO@C-N anode also shows good cycling performances (915 mA h g-1 after 200 cycles at 0.2 A g-1 and 768 mA h g-1 after 500 cycles at 0.5 A g-1).