Some Strategies in Designing Highly Efficient Photocatalysts for Degradation of Organic Pollutants in Water

Abstract

R.J.)Over the past decades, with the fast development of chemical industry, organic pollutants in water have become a major source of environmental pollution in waste fields. Photocatalysis, as a "green chemistry" technology, has attracted much attention in pollutants degradation due to its efficient degradation rate, high mineralization efficiency and low toxigenicity, ideally producing CO 2 and H 2 O as the end-products. Photocatalytic degradation of organic pollutants includes fabrication of photocatalytic materials, research of reaction kinetics and working mechanism. This Chapter presents some new strategies in the design of highly efficient photocatalysts for degradation of organic pollutants, such as the design and fabrication of hetero-structured or microspherical photocatalysts, and sonochemical synthesis of photocatalysts with novel nano-structures. The formation of well-defined junctions between two semiconductors with matchied electronic band structure can effectively facilitate charge transfer and suppress the recombination of photo-generated electrons and holes, leading to extremely high activity and stability. Once the photocatalysis is applied on a large scale, operating costs should be emphasized, and recycling of photocatalysts becomes important in order to cut down the operating costs to an affordable level. Compared to the conventional nano-powder

Molybdenum Disulfide-Based Photocatalysis:Bulk-to-Single Layer Structure and Related Photomechansim for Environmental Applications

“…The theoretical photocurrent density of chemically exfoliated MoS 2 is ~17.6 mA/cm 2 at 0.0 V vs. RHE under solar irradiation [17], and the solar energy conversion efficiency is ~18.7% for an ideal PEC cell. However, the photocatalytic activity of MoS 2 is limited by the factors mentioned thus far, which lead to low efficiencies and require larger potential to promote the photo-assisted water oxidation process [18]. Many researchers have tried to overcome these drawbacks of MoS 2 by decreasing the recombination rate through forming a composite or heterogeneous structure, as well as enhancing the conductivity by doping with metal and promoting the charge carrier transferability [19][20][21][22].…”