Hydrogel photocatalysts for efficient energy conversion and environmental treatment

Photocatalysts have attracted great research interest owing to their excellent properties and potential for simultaneously addressing challenges related to energy needs and environmental pollution.Photocatalytic particles need to be in contact with their respective media to exhibit efficient photocatalytic performances.However,it is difficult to separate nanometer-sized photocatalytic materials from reaction media later,which may lead to secondary pollution and a poor recycling performance.Hydrogel photocatalysts with a three-dimensional(3D)network structures are promising support materials for photocatalysts based on features such as high specific surface areas and adsorption capacities and good environmental compatibility.In this review,hydrogel photocatalysts are classified into two different categories depending on their elemental composition and recent progresses in the methods for preparing hydrogel photocatalysts are summarized.Moreover,current applications of hydrogel photocatalysts in energy conversion and environmental remediation are reviewed.Furthermore,a comprehensive outlook and highlight future challenges in the development of hydrogel photocatalysts are presented.

Synthesis of Activated Carbon from Polyethylene Terephthalate(PET)Plastic Waste and Its Application for Removal of Organic Dyes from Water

Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are discarded,they can cause serious harm to the environment and human health.In this study,PET plastic waste was used to create activated carbon using a physical activation process that involved using CO2 gas.The researchers investigated the effects of different temperatures,carbonization,and activation times on the resulting activated carbon’s surface area.The activated carbon was then analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),FTIR,and BET.The activated carbon created from PET plastic waste showed excellent absorption properties for methylene blue in aqueous solutions across a wide range of pH levels.By creating activated carbon from plastic waste,not only are environmental issues addressed,but high-value activated carbon is produced for environmental remediation purposes.

Carbon quantum dots-based semiconductor preparation methods,applications and mechanisms in environmental contamination

Photocatalyst is the most widespread method in advanced oxidation technologies,but due to the photoinduced electron combine easily with hole and the wavele ngth of adsorption is limited which will affect some practical applications.Carbon quantum dots(CQDs)is non-toxic and harmless green materials,it has the ability to improve the photocatalytic effect which is attributed to its good electrical and optical properties.Their up-conversion effect,photosensitization and electrical conductivity are assistants which help promote the photocatalytic effect in environmental applications.The key mechanisms of CQDs to improve photocatalysis can be roughly divided into three categories:1)Up-conversion effect conve rts the incident light into the emitted light with high ene rgy to solve the problem which is the light absorption range;2)CQDs act as a photosensitizer instead of valence band to provide electrons to the conduction band of semiconductor;3)CQD s can be used as the internal or external electronic conductor in materials to alleviate the trend of electron and hole separation.However,CQDs and CQDs-based photocatalysts have different views to solve environmental problems,so it is necessary to integrate different views.Therefore,this review is mainly aimed at the recent researches about the preparation processes of CQD,CQD s-based photocatalysts,and their ability to remove environmental pollutants,with a special emphasis on the mechanism for depredating pollutants.Furthermore,this paper analyzes and discusses the prospects and challenges of CQDs in the environmental field.