Interaction behavior, mechanisms and hazardous changes of microplastics on single and binary component pesticide in the environment and food: Diethofencarb and pyrimethanil.

In order to investigate the adsorption behavior and mechanism of microplastics (MPs) on multiple coexisting pesticides in practical systems, as well as their hazardous changes upon binding, diethofencarb and pyrimethanil were selected to be studied with four MPs. The adsorption rate of both pesticides would be faster in the binary-component case, conforming to pseudo-second-order kinetics, with adsorption sites and chemical adsorption dominating. And the more hydrophobic the pesticide, the faster the adsorption rate and the higher the adsorption capacity. Diethofencarb belonged to monolayer adsorption, whereas pyrimethanil belonged to monomolecular combined with multilayer adsorption, depending on the size of pesticides. And the adsorption process was both competitive and synergistic when pesticides coexist. In addition, the adsorption process was a spontaneous heat absorption process. Electrostatic forces have little effect on adsorption, while the adsorption capacity can be altered by the adsorption sites and hydrophobicity of MPs. The salting-out effect also facilitated the adsorption process. As for changes in hazard, the bioluminescence of A. fischeri wasn't significantly inhibited, lacking of acute environmental toxicity. However, in vitro digestion experiments demonstrated a significant increase in bioavailability of diethofencarb and pyrimethanil in combination with MPs. These findings suggest the stronger adsorption behaviors and higher loading capacities between pesticides and MPs could lead more serious hazards to the human body, which deserves further attention.

Facilitating the Hydrogen Evolution Reaction on Basal-Plane S Sites on MoS2@Ni3S2 by Dual Ti and N Plasma Treatment.

Atomic engineering of the basal plane active sites in MoS2 holds great promise to boost the electrocatalytic activity for hydrogen evolution reactions (HER), yet the performance optimization and mechanism exploration are still not satisfactory. Herein, we proposed a dual-plasma engineering strategy to implant Ti and N heteroatoms into the basal plane of MoS2 supported by Ni3S2 nanorods on nickel foam (MSNF) for efficient electrocatalysis of HER. Owing to the low formation energy of Ti dopants in MoS2 and the extra charge carriers introduced by N dopants, the optimally codoped samples N1.0@Ti500-MSNF demonstrate significant morphology changes from nanorods to urchin-like nanospheres with the surface active areas increased by seven-fold, as well as enhanced electrical conductivity in comparison with the nondoped counterparts. The HER performance of N1.0@Ti500-MSNF is comparable with the Pt-based catalyst: overpotential of 26 mV at 20 mA cm-2, Tafel slope of 35.6 mV dec-1, and long-term stability over 50 h. First-principles calculation reveals that N doping accelerates the dissociation of water molecules while Ti doping activates the adjacent S sites for hydrogen adsorption by lowering the Gibbs free energy, resulting in excellent HER activity. This work thus provides an effective strategy for basal plane engineering of MoS2 heterostructures toward high-performance HER and sustainable energy supply at reasonable costs.