Non-radical-dominated catalytic degradation of methylene blue by magnetic CoMoO4/CoFe2O4 composite peroxymonosulfate activators.

In this study, magnetic CoMoO4/CoFe2O4 (CMO/CFO) nanospheres with a core-shell structure were synthesized via two-step hydrothermal methods. The obtained particles were employed as catalysts to activate peroxymonosulfate (PMS) and degrade methylene blue (MB). The physico-chemical characterizations of the synthesized CMO/CFO showed that the CMO shell contributed to the enhancement of redox conversion and the increase in the concentration of oxygen vacancies (OVs). By examining reactive oxygen species (ROS) in the CMO/CFO/PMS system, the MB degradation was dominated by a non-radical pathway, and 1O2 was identified as the most abundant ROS. Besides, the CMO/CFO exhibited faster reaction kinetics than the pristine CFO. Moreover, the magnetic properties guaranteed the recycling and reuse of CMO/CFO, and the removal rate of MB was maintained at ∼94% after continuous use five times. Both the tolerance to SO42-and the wide pH range where the material is applicable make it a promising catalyst for dyeing wastewater treatment.

Improvement of Heterojunction Nanomaterials Photoelectrochemical Properties by Sol-Gel Synthesis and Hydrothermal Reaction.

The ZnO nanorod arrays (NRs)/CuAlO2 laminar crystal thin films (LFs)/Ni heterojunctions with delafossite structure were prepared by sol-gel synthesis for LFs and hydrothermal for NRs. X-ray diffraction analysis demonstrates the typical delafossite structure CuAlO2 and pure ZnO of R¯3m space group. Compared with a traditional CuAlO2/Ni laminar films (LFs) nanostructure, the photocurrent of this heterojunction nanostructure is significantly increased. Note that a significant blue-shift of the absorption edge and a favorable forward current to reverse current ratio at applied voltages of -0.75 to +2 V were observed in this heterojunction with the increase of Zn2+ ion concentration in the hydrothermal reaction. Moreover, the photoelectrochemical characteristics recorded under AM 1.5 illumination with 100 mW/cm2 light intensity at 0 V (vs. Ag/AgCl), while the highest photocurrent density arrive at 3.59 mA/cm2. This study demonstrates that heterojuction nanostructure, which is easily adapted to other chemical systems, is a promising technique for improving photoelectro-chemical properties of low-cost solar cells.