Review on the treatment of organic pollutants in water by ultrasonic technology

The application of ultrasonic technology in the treatment of organic pollutants in water has attracted more and more attention in recent years. Compared with conventional treatment, ultrasonic treatment is more efficient and time saving. Ultrasonic technology is effective for the degradation of many refractory organic pollutants. In this paper, the principle, influencing factors and various methods of ultrasonic degradation of organic pollutants are studied in view of ultrasonic treatment alone, ultrasound treatment methods combined with biocatalysts, chemical oxidation and adsorption techniques, respectively. In addition, the problems existing in the treatment of organic pollutants in water by ultrasonic technology are analyzed and the development direction is put forward.

n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties

In this study, ZnO nanorods (NRs) were hydrothermally grown on an Au-coated glass substrate at a relatively low temperature (90 °C), followed by the deposition of Ag₂CrO₄ particles via a successive ionic layer adsorption and reaction (SILAR) route. The content of the Ag₂CrO₄ particles on ZnO NRs was controlled by changing the number of SILAR cycles. The fabricated ZnO–Ag₂CrO₄ heterojunction photoelectrodes were subjected to morphological, structural, compositional, and optical property analyses; their photoelectrochemical (PEC) properties were investigated under simulated solar light illumination. The photocurrent responses confirmed that the ability of the ZnO–Ag₂CrO₄ heterojunction photoelectrodes to separate the photo-generated electron–hole pairs is stronger than that of bare ZnO NRs. Impressively, the maximum photocurrent density of about 2.51 mA cm⁻² at 1.23 V (vs. Ag/AgCl) was measured for the prepared ZnO–Ag₂CrO₄ photoelectrode with 8 SILAR cycles (denoted as ZnO–Ag₂CrO₄-8), which exhibited about 3-fold photo-enhancement in the current density as compared to bare ZnO NRs (0.87 mA cm⁻²) under similar conditions. The improvement in photoactivity was attributed to the ideal band gap and high absorption coefficient of the Ag₂CrO₄ particles, which resulted in improved solar light absorption properties. Furthermore, an appropriate annealing treatment was proven to be an efficient process to increase the crystallinity of Ag₂CrO₄ particles deposited on ZnO NRs, which improved the charge transport characteristics of the ZnO–Ag₂CrO₄-8 photoelectrode annealed at 200 °C and increased the performance of the photoelectrode. The results achieved in the present work present new insights for designing n–n heterojunction photoelectrodes for efficient and cost-effective PEC applications and solar-to-fuel energy conversions.

ZnO NRs hydrothermally grown on Au coated glass substrate, followed by deposition of Ag₂CrO₄ particles via SILAR route. The content of the Ag₂CrO₄ particles on the ZnO NRs were controlled by changing the number of SILAR cycles.

Bio-inspired Z-scheme g-C3N4/Ag2CrO4 for efficient visible-light photocatalytic hydrogen generation

Due to low charge separation efficiency and poor stability, it is usually difficult for single-component photocatalysts such as graphitic carbon nitride (g-C₃N₄) and silver chromate (Ag₂CrO₄) to fulfill photocatalytic hydrogen production efficiently. Z-scheme charge transport mechanism that mimics the photosynthesis in nature is an effective way to solve the above problems. Inspired by photosynthesis, we report Ag₂CrO₄ nanoparticles-decorated g-C₃N₄ nanosheet as an efficient photocatalyst for hydrogen evolution reaction (HER) with methanol as sacrificial agent. The formation of Z-scheme g-C₃N₄/Ag₂CrO₄ nanosheets photocatalysts could inhibit the recombination of photogenerated electron-hole pairs, promote the generation of hydrogen by photosplitting of water. The experiment results indicate that g-C₃N₄/Ag₂CrO₄ nanocomposites present enhanced photocatalytic activity and stability in the H₂ evolution of water splitting. And the nanocomposites g-C₃N₄/Ag₂CrO₄(23.1%) show the 14 times HER efficiency compared to that of bare g-C₃N₄.

Synthesis of In2O3 nanoparticle/TiO2 nanobelt heterostructures for near room temperature ethanol sensing

The obtained In₂O₃ nanoparticle/TiO₂ nanobelt heterostructures exhibit a high sensitive toward ethanol at near room temperature of 45 °C and low detection limit of 1 ppm.

Synthesis and characterization of Z-scheme In2S3/Ag2CrO4 composites with an enhanced visible-light photocatalytic performance

Efficient charge transfer at the interfaces of an In₂S₃/Ag₂CrO₄ composite, due to the formation of a Z-scheme system between In₂S₃ and Ag₂CrO₄, effectively facilitates photogenerated electron–hole pair separation.