Metal chalcogenides (CuS or MoS2)-modified TiO2 as highly efficient bifunctional photocatalyst nanocomposites for green H2 generation and dye degradation.

Herein, we report the modification of TiO2 nanostructures with two different metal chalcogenides (CuS or MoS2). The effect of the preparation scheme (hydrothermal and coprecipitation methods) and the mass ratio of metal chalcogenides were investigated. The as-synthesized photocatalyst nanocomposites were fully characterized by various techniques. Moreover, the photo/electrochemical analysis were performed to investigate the photoelectric properties and photocatalytic mechanism. The photocatalytic performance was evaluated using two test reactions. In the case of H2 generation via water splitting, it was found that 0.5 wt% CuS-TiO2 synthesized via the coprecipitation method exhibited an initial hydrogen evolution rate (HER) of 2.95 mmol h-1 g-1. While, the optimized 3 wt% MoS2-TiO2 synthesized by the hydrothermal method, showed an HER of 1.7 mmol h-1 g-1. Moreover, the degradation efficiency of methylene blue dye was 98% under UV-Vis light irradiation within 2 h over 0.5 CT_PP and 3MT_HT. Under visible irradiation, the degradation efficiency was 100% and 96% for 3MT_PP and 0.5CT_HT in the presence of H2O2, respectively. This study has proven that metal chalcogenides can act as effective, stable, and low-cost bifunctional co-catalysts to enhance the overall photocatalytic performance.

High adsorption capacity of phenol and methylene blue using activated carbon derived from lignocellulosic agriculture wastes.

The resources of clean water worldwide are very limited, and climate change is already affecting the available supplies. Therefore, developing a low-cost, highly efficient, and recyclable adsorbent to upgrade water quality has become an essential task. Herein, we report the fabrication of activated carbon (AC) adsorbents derived from lignocellulosic wastes. Both physical and chemical activation were investigated to modify the surface texture properties. The results indicated that increasing the activation temperature, whether physically or chemically, increases the specific surface area (SBET). On the contrary, increasing the amount of the chemical activating agent significantly decreases the SBET values. The SBET of 1771, 2120, and 2490 m2 g-1 were obtained for water vapor, K2CO3 and KOH, at activation temperatures of 950 °C, 800 °C, and 800 °C, respectively. Methylene blue (MB) and phenol were used as adsorbates for the adsorption experiment. Adsorption of methylene blue dye revealed the ability of the water activated carbon to remove more than 95% of the dye (100 ppm) within 5 min with an adsorption capacity of 148.8 mg g-1. For phenol adsorption, Several parameters were investigated, including initial concentration (50-250 ppm), pH (2-10), contact time (5-60 min), and temperature (25-45 °C). The highest adsorption capacity of phenol achieved was 158.9 mg g-1. The kinetics of adsorption of phenol was better described by pseudo-second-order reaction while the isotherm process using Langmuir model. This study presents a roadmap for conversion of lignocellulosic biomass waste into highly efficient porous carbon adsorbents.