Harnessing eco-friendly additives to manipulate zinc-ion solvation structures towards stable zinc metal batteries

Considerable research efforts have been dedicated to investigating the side reactions and the growth of Zn dendritic in aqueous zinc-ion batteries(AZIBs).The incorporation of organic solvents as additives in electrolytes has yielded highly promising results.Nevertheless,their pervasive use has been hindered by concerns regarding their toxicity,flammability,and economic viability.Herein,we propose the utilization of γ-valerolactone(γ-V),a novel eco-friendly solvent,as an alternative for conventional organic additives to improve the performance of Zn anode.Experimental investigations and theoretical analyses have verified that γ-V additives can diminish the Zn^(2+)-desolvation energy and enhance Zn^(2+) transport kinetics.The adsorbed γ-V molecules modulate the nucleation and diffusion of Zn^(2+),facilitating Zn growth along the(002) crystal plane,thus inhibiting dendrite formation and side reactions.Consequently,the modified electrolyte with 3% γ-V exhibit highly reversible cycling for 2800 h at1 mA cm^(-2) and 1 mA h cm^(-2) in Zn//Zn symmetric cell.The Zn//KVOH coin cells deliver a capacity retention of 74.7% after 1000 cycles at 5 A g^(-1).The Zn//KVOH pouch cells maintain a capacity retention of78.7% over 90 cycles at 3 A g^(-1).Notably,the γ-V additives also effectively alleviate the self-discharge phenomenon.This work provides valuable insights on the development of aqueous zinc-ion batteries with superior safety through the modulation of electrolytes using eco-friendly additives.

Efficient oxygen reduction reaction by a highly porous,nitrogen-doped carbon sphere electrocatalyst through space confinement effect in nanopores

A highly porous nitrogen-doped carbon sphere(NPC)electrocatalyst was prepared through the carbonization of biomass carbon spheres mixed with urea and zinc chloride in N_(2) atmosphere.The sample carbonized at.1000℃ demonstrates a superior oxygen reduction reaction(ORR)performance over the Pt/C electrocatalyst,while its contents of pyridinic nitrogen and graphitic nitrogen are the lowest among samples synthesized at the same or lower carbonization temperatures.This unusual result is explained by a space confinement effect from the microporous and mesoporous structures in the microflakes,which induces the further reduction of peroxide ions or other oxygen species produced in the first step reduction to water to have the preferred overall four electron reduction ORR process.This work demonstrates that in addition to the amount or species of its aptive sites,the space confinement can be a new approach to enhance the ORR performance of precious-metal-free,nitrogen-doped carbon electrocatalysts.

Palladium nanoparticles supported on amine-functionalized glass fiber mat for fixed-bed reactors on the effective removal of hexavalent chromium by catalytic reduction

Palladium nanoparticles were deposited on the amine-grafted glass fiber mat （GFM-NH2） catalyst support by a conventional impregnation process followed by the borohydride reduction in aqueous solution at room temperature to create the designed Pd/GFM-NH2 catalyst. By the use of large size glass fiber mat without nano/mesopores as the catalyst support, the internal mass transfer limitations due to the existence of nano/mesopores on the catalyst support were eliminated and the Pd/GFM-NH2 catalyst could be easily separated from treated water due to the large size of the catalyst support. Batch experiments demonstrate its good catalytic reduction performance of Cr（VI） with formic acid as the reducing agent. It also demonstrated an efficient Cr（VI） removal and stability in a lab-prepared, packed fixed-bed tube reactor for the continuous treatment of Cr（VI）-containing water. Thus, it has a good potential for the catalytic reduction of Cr（VI） in the water treatment practice.