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The development of suitable catalysts poses a challenge for the peroxymonosulfate (PMS) activation system used in decontamination process. Here we constructed a series of vacancy-strengthened Cu/Co composite oxides (CuCoO) composed of CuCo2O4and CuO containing multiple Lewis acid sites. The results demonstrate that the as-prepared CuCoO-2 exhibited exceptional activation performance, broad-ranging degradation capacity, remarkable reusability and stability. The optimized CuCoO-2+PMS system achieved complete removal of methylene blue (MB) in 40min, while maintaining a degradation efficiency of above 86% even after 5 cycles. A comprehensive survey revealed that hydroxyl radical (·OH), sulfate radical (SO4.-) and singlet oxygen (1O2) collectively contribute to the degradation of MB in the CuCoO-2+PMS system. Especially, 1O2was the dominant active species. The synergism of various Lewis acid sites (Cu+/2+, Co2+/3+and VO/N) as unsaturated surface-bound centers played a pivotal role in promoting non-radical-driven activation of PMS. Meanwhile, the generated VO/Nfacilitated enhanced metallic valence circulation in CuCoO-2, strengthening electron mediation between PMS and MB. Additionally, possible degradation pathways and toxicity evaluations of MB and its intermediates were proposed. In conclusion, this work offers valuable insights into PMS activation by vacancy-strengthened CuCoO and is of great significance for water purification.

The removal of highly toxic heavy metal ions is essentially the migration of heavy metal ions from water to materials through adsorption, complexation, exchange, and other forms. However, heavy metals still exist as highly toxic ions on the surface of materials, easily desorbed, and cause secondary pollution. In this study, a novel primary battery of graphene-supported zero-valent copper/iron bimetallic composites (Cu/Fe/rGO) was first prepared with copper as the positive electrode, iron as the negative electrode, and graphene as the "wire". The network-like nanoscale primary battery was fabricated for the reduction and removal of typical highly toxic heavy metal ions (Pb2+) from the water environment. The removal rate of Pb2+within 20minutes was 95.28%. The Pb-immobilized Cu/Fe/rGO primary battery after treatment can be easily separated via a weak magnetic field and maintained an excellent removal rate of Pb2+during 6 cycles of use. The great potential of Cu/Fe/rGO primary battery in Pb2+reduction removal was due to its high reduction ability, large surface area, and magnetic separability. This study provides an important foundation for the rapid and stable removal of heavy metals from water, which may have a tremendous application prospect in environmental fields.

The use of peroxymonosulfate (PMS) activation to eliminate organic contaminants is a promising technology to purify water owing to its strong reactivity. However, because of the existed rate limiting step, the performance of PMS activation was restrained and required external energy consumption. Therefore, a new strategy was proposed to solve this problem by preparing catalysts with abundant electron-rich sites and electron traps to accelerate PMS activation. In this research, a novel MnCeOx-H catalyst with rich surface oxygen vacancies was firstly synthesized to accelerate the transfer of electrons among the catalysts, oxidant and pollutants. The contaminants were rapidly eliminated in the MnCeOx-H/PMS system, while the reaction rate constant of MnCeOx-H/PMS system was 30 times higher than that of CeO2/PMS system. The surface oxygen vacancies were able to adsorb and trap PMS, then the free electrons of oxygen vacancies would reduce PMS and produced HO•, 1O2and SO4•-, while 1O2played a major role. The contaminants which acted as electron-donors in this system were adsorbed at Mn, Ce sites, achieving effective conversion recycling of Ce(IV)/Ce(III), Mn(III)/Mn(II) and Mn(IV)/Mn(III). This discovery is believed to inaugurate a novel way for designing powerful electron-rich sites and electron traps to accelerate PMS activation for contaminants degradation.

This paper investigates the implication of correlation ambiguity to investor behavior, asset pricing and issuers' listing choices from a market microstructure perspective. We introduce two markets to a multi-asset model: Market A is transparent and Market B is opaque, or Market A with low and Market B with high ambiguity perceived by investors. Each firm can choose only a unique market to list its stock. Due to ambiguity aversion, a naïve investor's demand function demonstrates piecewise linear. Such trading behavior may lead to different equilibria and hence different market-clearing prices for each listing outcome. Rational entrepreneurs make their optimal listing decisions depending on asset prices on alternative markets. We further demonstrate that a crafted design of specific features of the microstructure, such as listing standards and disclosure requirements, can effectively reduce the perceived ambiguity and induce more naïve investors' participation to improve market liquidity, maintain greater volume, and lower the cost of capital, so as to attract more new listings.