Piezocatalysis is a promising technology to address environmental pollution by converting mechanical energy into chemical energy. Herein, MoSe2 nanosheets with different 1T phase percentages (ranging from 31–80%) were constructed by adjusting hydrothermal temperature. Moreover, the roles of phase engineering in the piezocatalysis were thoroughly investigated by degrading Rhodamine B and reducing Cr (VI) in ultrasonic vibration. The experimental results indicated that MoSe2 with the higher percentage 1T phase contributes to better conductivity, the higher polarization, more active centers and better piezocatalytic performance. In particular, the observed kobs constant and the ultrafast degradation rate k of MoSe2 prepared at 220 ℃ (MoSe2-220) with the highest percentage 1T phase (80%) are the fastest among all reported catalysts to date. The ultrahigh activity is attributed to the establishment of an internal electric field at the 1T and 2H phase boundaries, which drives the segregation of electron-hole pairs in MoSe2-220 nanosheets. Furthermore, ·O2− and ·OH as main reactive species were confirmed and a rational mechanism was finally put forward. This study offers a clear understanding of phase engineering in piezocatalysis and provides an efficiency strategy to construct highly efficient piezocatalysts.
A series of Janus hemispheres with a patchy hemispherical
surface
and a flat undersurface were synthesized through controlled polymerization-induced
phase separation within emulsified wax droplets. The hemispherical
shape was generated through the polymerization of styrene within wax
droplets, followed by the grafting of hydrophilic polymers on the
exposed surface. Then, the patchy hemispherical surface was achieved
after introducing the hydrophobic acrylate monomers within wax droplets
and controlling the polymerization-induced phase separation. The morphological
evolution of patches was recorded via the reaction time, followed
by their morphological regulation through the type, feeding amount,
and cross-linking degree of acrylate monomers. A functional monomer,
vinyl benzyl chloride (VBC), was also used to copolymerize the patches
for grafting a zwitterionic polymer via surface-initiated atom transfer
radical polymerization (SI-ATRP). The as-obtained Janus hemispheres
were employed to fabricate robust coatings with wettability tuned
from superhydrophobicity to underwater superoleophobicity by the grafted
zwitterionic polymers.
Complex pollutants are discharging and accumulating in rivers and oceans, requiring a coupled strategy to resolve pollutants efficiently. A novel method is proposed to treat multiple pollutants with C,N co-doped TiO2 hollow nanofibers coated stainless steel meshes which can realize efficient oil/water separation and visible light-drove dyes photodegradation. The poly(divinylbenzene-co-vinylbenzene chloride), P(DVB-co-VBC), nanofibers are generated by precipitate cationic polymerization on the mesh framework, following with quaternization by triethylamine for N doping. Then, TiO2 is coated on the polymeric nanofibers via in-situ sol–gel process of tetrabutyl titanate. The functional mesh coated with C,N co-doped TiO2 hollow nanofibers is obtained after calcination under nitrogen atmosphere. The resultant mesh demonstrates superhydrophilic/underwater superoleophobic property which is promising in oil/water separation. More importantly, the C,N co-doped TiO2 hollow nanofibers endow the mesh with high photodegradation ability to dyes under visible light. This work draws an affordable but high-performance multifunctional mesh for potential applications in wastewater treatment.
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