Progress in Promising Semiconductor Materials for Efficient Photoelectrocatalytic Hydrogen Production.

Photoelectrocatalytic (PEC) water decomposition provides a promising method for converting solar energy into green hydrogen energy. Indeed, significant advances and improvements have been made in various fundamental aspects for cutting-edge applications, such as water splitting and hydrogen production. However, the fairly low PEC efficiency of water decomposition by a semiconductor photoelectrode and photocorrosion seriously restrict the practical application of photoelectrochemistry. In this review, the mechanisms of PEC water decomposition are first introduced to provide a solid understanding of the PEC process and ensure that this review is accessible to a wide range of readers. Afterwards, notable achievements to date are outlined, and unique approaches involving promising semiconductor materials for efficient PEC hydrogen production, including metal oxide, sulfide, and graphite-phase carbon nitride, are described. Finally, four strategies which can effectively improve the hydrogen production rate-morphological control, doping, heterojunction, and surface modification-are discussed.

Study on regeneration characteristics of granular activated carbon using ultrasonic and thermal methods.

Dye wastewater is a type of high-concentration, high chromaticity, and high salinity organic wastewater, which is generally treated with activated carbon adsorbent. The effective regeneration of granular activated carbon (GAC) is the key to reducing the operating cost of GAC in the wastewater treatment process. The regeneration characteristics of saturated GAC adsorbed on 288 orange dye wastewater were studied by using the ultrasonic coupled thermal regeneration method. The results showed that the regeneration efficiency of GAC adsorbed on 288 orange dye wastewater increased with the increase of ultrasound power. The optimal ultrasound frequency and regeneration temperature were determined to be 45 kHz and 60 ℃, and the relationship between regeneration times and carbon loss rate was explored. The combination of ultrasound and high-temperature heating methods has successfully improved the regeneration efficiency of GAC and significantly reduced the high-temperature thermal regeneration time of GAC, thereby reducing the mass loss rate of GAC. The performance changes of fresh activated carbon (FAC), saturated activated carbon (SAC), ultrasonic regeneration of activated carbon (UAC), and thermal regeneration of activated carbon (TAC) during the combined regeneration process were explored by characterizing the regenerated GAC. Infrared characterization showed that the C-O group of GAC was significantly weakened after coupling treatment, indicating that ultrasonic treatment can significantly enhance the desorption effect of thermal regeneration. The microjet, shock wave, and cavitation effects generated by ultrasonic treatment restore the specific surface area of GAC, mainly increasing the micropore volume and pore size of GAC, and enhancing the treatment effect of thermal regeneration.