Novel Z-scheme binary zinc tungsten oxide/nickel ferrite nanohybrids for photocatalytic reduction of chromium (Cr (VI)), photoelectrochemical water splitting and degradation of toxic organic pollutants.

A simple hydrothermal approach was demonstrated for synthesizing a coupled NiFe2O4-ZnWO4 nanocomposite, wherein one-dimensional ZnWO4 nanorods were inserted into two-dimensional NiFe2O4 nanoplates. Herein, we evaluated the photocatalytic removal of Cr(VI), and degradation of tetracycline (TC) and methylene blue (MB) by the nanocomposite, as well as its ability to split water. The ZnWO4 nanorods enriched the synergistic interactions, upgraded the solar light fascination proficiency, and demonstrated outstanding detachment and migration of the photogenerated charges, as confirmed by a transient photocurrent study and electrochemical impedance spectroscopy measurements. Compared to pristine NiFe2O4 and ZnWO4, the NiFe2O4-ZnWO4 nanocomposite exhibited a higher Cr(VI) reduction (93.5%) and removal of TC (97.9%) and MB (99.6%). Radical trapping results suggested that hydroxyl and superoxide species are dominant reactive species, thereby facilitating the Z-scheme mechanism. Furthermore, a probable photocatalytic mechanism was projected based on the experimental results. The photoelectrochemical analysis confirmed that NiFe2O4-ZnWO4 exhibited minor charge-transfer resistance and large photocurrents. We propose a novel and efficient approach for designing a coupled heterostructured nanocomposites with a significant solar light ability for ecological conservation and water splitting.

An effective CuO/Bi2WO6 heterostructured photocatalyst: Analyzing a charge-transfer mechanism for the enhanced visible-light-driven photocatalytic degradation of tetracycline and organic pollutants.

Over the past few years, industrial pollution has had a negative impact on aquatic life by releasing significant amounts of hazardous chemicals into the ecosystem. Therefore, it is imperative to develop photocatalytic materials with good photocatalytic activity and easy separation. Photocatalytic degradation has been employed for the removal of such contaminants using binary hybrid nanocomposites as photocatalysts. In the present study, binary CuO/Bi2WO6 (CuBW) nanocomposites with different loadings of Bi2WO6 (~5, 10, and 15 mg) were successfully constructed using a simple hydrothermal method and used as a potential photocatalyst for the degradation of tetracycline (TC) and methylene blue (MB) under visible-light irradiation. The structure, surface morphology, and optical properties were studied to investigate the formation of the heterostructure. Among the prepared samples, the CuBW nanocomposite containing the optimum content of Bi2WO6 (~10 mg) exhibited superior activity toward the photocatalytic degradation of TC (97.72%) in 75 min and MB (99.43%) in 45 min under visible-light illumination. Radical trapping experiments suggested that holes and •OH radicals were the dominant reactive species during the photocatalytic process. The photoelectrochemical results also confirmed the improved separation and transfer of electron-hole pairs at the interface of Bi2WO6 and CuO. Our results demonstrate that the binary CuO/Bi2WO6 nanocomposite has significant potential applications in the field of photocatalysis due to its enhanced separation of the photoexcited charge carriers and strong synergistic interactions.

Ultra-small zinc oxide nanosheets anchored onto sodium bismuth sulfide nanoribbons as solar-driven photocatalysts for removal of toxic pollutants and phtotoelectrocatalytic water oxidation.

Heterostructured nanohybrids were prepared from sodium bismuth sulfide (NaBiS2) and zinc oxide (ZnO) through hydrothermal process. The nanocomposite was used for tetracycline (TC) degradation as well as photoelectrochemical (PEC) water oxidation. Morphology and structural analyses were performed to confirm the dispersion of ultra-small ZnO nanosheets into the NaBiS2 nanoribbons. By tuning the band gap, it was possible to degrade tetracycline toxic pollutant within 90 min under the simulated solar light irradiation, while PEC suggested a lower charge-transfer resistance, high photocurrent response, and exceptionally good stability. The highest photocurrent density of 0.751 mAcm-2 vs. Ag/AgCl in 0.1 M Na2SO3 solution was observed under solar-light illumination. Detailed photocatalytic mechanisms for the degradation of TC and PEC water oxidation are discussed.