Plasma-grafted anion-exchange membrane preparation and process analysis

New block poly(ether sulfone) based anion exchange membranes with rigid side-chains and high-density quaternary ammonium groups for fuel cell application

We report a series of novel poly(ether sulfone) based anion exchange membranes (AEMs) with relatively good stability due to their rigid side-chains and heterocyclic quaternary ammonium groups. The AEMs show appropriate performance in AEM fuel cells.

Interface Modulation of MoS2 /Metal Oxide Heterostructures for Efficient Hydrogen Evolution Electrocatalysis

Developing efficient earth-abundant MoS₂ based hydrogen evolution reaction (HER) electrocatalysts is important but challenging due to the sluggish kinetics in alkaline media. Herein, a strategy to fabricate a high-performance MoS₂ based HER electrocatalyst by modulating interface electronic structure via metal oxides is developed. All the heterostructure catalysts present significant improvement of HER electrocatalytic activities, demonstrating a positive role of metal oxides decoration in promoting the rate-limited water dissociation step for the HER mechanism in alkaline media. The as-obtained MoS₂ /Ni₂ O₃ H catalyst exhibits a low overpotential of 84 mV at 10 mA cm^-2 and small charge-transfer resistance of 1.5 Ω in 1 m KOH solution. The current density (217 mA cm^-2 ) at the overpotential of 200 mV is about 2 and 24 times higher than that of commercial Pt/C and bare MoS₂ , respectively. Additionally, these MoS₂ /metal oxides heterostructure catalysts show outstanding long-term stability under a harsh chronopotentiometry test. Theoretical calculations reveal the varied sensitivity of 3d-band in different transition oxides, in which Ni-3d of Ni₂ O₃ H is evidently activated to achieve fast electron transfer for HER as the electron-depletion center. Both electronic properties and energetic reaction trends confirm the high electroactivity of MoS₂ /Ni₂ O₃ H in the adsorption and dissociation of H₂ O for highly efficient HER in alkaline media.

Fabrication of an Anion-Exchange Membrane by Pore-Filling Using Catechol-1,4-Diazabicyclo-[2,2,2]octane Coating and Its Application to Reverse Electrodialysis

We have successfully exploited the Michael-type addition reaction between catechol and DABCO (1,4-diazabicyclo-[2,2,2]octane) molecules under alkaline conditions for the formation of new quaternary ammonium (QA) groups in an anion-exchange membrane. The anion-exchange membranes (AEMs) were prepared using the pore-filling method by addition of electrolytes (vinyl benzyl trimethylammonium chloride (VBTMA), dopamine methacrylamide (DMA) bearing a catechol group, and ethylene glycol diacrylate as a cross-linker) to a porous substrate. The formation of new QA groups by the reaction of DABCO with catechol components was confirmed by characterization of new peaks in the Fourier transform infrared spectra of the AEMs. The DABCO-bound AEM demonstrated a significant decrease in area resistance (0.4 Ω·cm²) and increase in permselectivity (94%). Furthermore, the electrochemical properties of the AEMs could be controlled by altering the concentrations of VBTMA and DMA and the formation of new bonds between DMA and DABCO. The calculated theoretical (4.31 W/m²) and practical (1.52 W/m²) power densities during a reverse electrodialysis (RED) process employing the membrane with the best properties (E2C1-DMA0.5-DABCO) were by 33 and 18% higher than those of a system utilizing a commercial membrane, Neosepta AMX (3.25 and 1.29 W/m²). Therefore, the AEM synthesized in this study is a good candidate for use in RED applications.