Synergistic Effect of Amorphous Ti(IV)-Hole and Ni(II)-Electron Cocatalysts for Enhanced Photocatalytic Performance of Bi2WO6

Bi2WO6 has become a common photocatalyst due to its advantages of simple synthesis and high activity. However, the defects of pure Bi2WO6 such as low light reception hinder its application in photocatalysis. In this study, based on the modification of Bi2WO6 with Ti(IV) as a cavity co-catalyst, new Ni- and Ti-doped nanosheets of Bi2WO6 (Ni/Ti-Bi2WO6) were prepared by a one-step wet thermal impregnation method and used for the photocatalytic degradation of tetracycline. The experimental results showed that the photocatalytic activity of Ni/Ti-Bi2WO6 modified by the two-component catalyst was significantly better than those of pure Bi2WO6 and Ti-Bi2WO6 modified with Ti(IV) only. The photocatalytic effect of Ni/Ti-Bi2WO6 with different Ni/Ti molar ratios was investigated by the degradation of TC. The results showed that 0.4Ni/Ti-Bi2WO6 possessed the best photocatalytic performance, with a degradation rate of 92.9% at 140 min TC. The results of cycling experiments showed that the catalyst exhibited high stability after five cycles. The scavenger experiment demonstrated that the h+ and O2− were the main reactive species. The enhanced photocatalytic activity of Bi2WO6 could be attributed to the synergistic effect between the Ti(IV) as a hole cocatalyst and Ni(II) as an electron cocatalyst, which effectively promoted the separation of photogenerated carriers.

Nanoremediation technologies for sustainable remediation of contaminated environments: Recent advances and challenges

A major and growing concern within society is the lack of innovative and effective solutions to mitigate the challenge of environmental pollution. Uncontrolled release of pollutants into the environment as a result of urbanisation and industrialisation is a staggering problem of global concern. Although, the eco-toxicity of nanotechnology is still an issue of debate, however, nanoremediation is a promising emerging technology to tackle environmental contamination, especially dealing with recalcitrant contaminants. Nanoremediation represents an innovative approach for safe and sustainable remediation of persistent organic compounds such as pesticides, chlorinated solvents, brominated or halogenated chemicals, perfluoroalkyl and polyfluoroalkyl substances (PFAS), and heavy metals. This comprehensive review article provides a critical outlook on the recent advances and future perspectives of nanoremediation technologies such as photocatalysis, nano-sensing etc., applied for environmental decontamination. Moreover, sustainability assessment of nanoremediation technologies was taken into consideration for tackling legacy contamination with special focus on health and environmental impacts. The review further outlines the ecological implications of nanotechnology and provides consensus recommendations on the use of nanotechnology for a better present and sustainable future.

Ag2S-Sensitized NiO-ZnO Heterostructures with Enhanced Visible Light Photocatalytic Activity and Acetone Sensing Property

Visible light-driven Ag2S-grafted NiO-ZnO ternary nanocomposites are synthesized using a facile and cost-effective homogeneous precipitation method. The structural, morphological, and optical properties were extensively studied, confirming the formation of ternary nanocomposites. The surface area of the synthesized nanocomposites was calculated by electrochemical double-layer capacitance (C dl). Ternary Ag2S/NiO-ZnO nanocomposites showed excellent visible light photocatalytic property which increases further with the concentration of Ag2S. The maximum photocatalytic activity was shown by 8% Ag2S/NiO-ZnO with a RhB degradation efficiency of 95%. Hydroxyl and superoxide radicals were found to be dominant species for photodegradation of RhB, confirmed by scavenging experiments. It is noteworthy that the recycling experiments demonstrated high stability and recyclable nature of the photocatalyst. Moreover, the electrochemical results indicated that the prepared nanocomposite exhibits remarkable activity toward detection of acetone. The fabricated nanocomposite sensor showed high sensitivity (4.0764 μA mmol L-1 cm-2) and a lower detection limit (0.06 mmol L-1) for the detection of acetone. The enhanced photocatalytic and the sensing property of Ag2S/NiO-ZnO can be attributed to the synergistic effects of strong visible light absorption, excellent charge separation, and remarkable surface properties.

A Bi2WO6/Ag2S/ZnS Z-scheme heterojunction photocatalyst with enhanced visible-light photoactivity towards the degradation of multiple dye pollutants

A novel visible-light-driven Z-scheme heterojunction, Bi₂WO₆/Ag₂S/ZnS, was synthesized and its photocatalytic activity was evaluated for the treatment of a binary mixture of dyes, and its physicochemical properties were characterized using FT-IR, XRD, DRS and FE-SEM techniques. The Bi₂WO₆/Ag₂S/ZnS Z-scheme heterojunctions not only facilitate the charge separation and transfer, but also maintain the redox ability of their components. The superior photocatalytic activity demonstrated by the Z-scheme Bi₂WO₆/Ag₂S/ZnS attributes its unique properties such as the rapid generation of electron–hole pairs, slow recombination rate, and narrow bandgap. The performance of the Bi₂WO₆/Ag₂S/ZnS was evaluated for the simultaneous degradation of methyl green (MG) and auramine-O (AO) dyes, while the influences of the initial MG concentration (4–12 mg L⁻¹), initial AO concentration (2–6 mg L⁻¹), pH (3–9), irradiation time (60–120 min) and photocatalyst dosage (0.008–0.016 g L⁻¹) were investigated through the response surface methodology. The desirability function approach was applied to optimize the process and results revealed that maximum photocatalytic degradation efficiency was obtained at optimum conditions including 6.08 mg L⁻¹ of initial MG concentration, 4.04 mg L⁻¹ of initial AO concentration, 7.25 of pH, 90.58 min of irradiation time and 0.013 g L⁻¹ of photocatalyst dosage. In addition, a possible photocatalytic mechanism of the Bi₂WO₆/Ag₂S/ZnS heterojunction was proposed based on the photoinduced charge carriers.

A Z-scheme Bi₂WO₆/Ag₂S/ZnS heterojunction was successfully synthesized as a novel visible-light-driven photocatalyst for the degradation of multiple dye pollutants.

Novel Ag2S quantum dot modified 3D flower-like SnS2 composites for photocatalytic and photoelectrochemical applications

Novel Ag₂S quantum dot modified 3D flower-like SnS₂ composites exhibit highly efficient photodegradation of MO and photocatalytic H₂ production.

Fabrication of hierarchically structured novel redox-mediator-free ZnIn2S4 marigold flower/Bi2WO6 flower-like direct Z-scheme nanocomposite photocatalysts with superior visible light photocatalytic efficiency

Efficient direct Z-scheme ZnIn₂S₄ marigold flower/Bi₂WO₆ flower photocatalyst for the degradation of metronidazole pharmaceutical under visible-light irradiation.

Amorphous Ti(iv)-modified Bi2WO6 with enhanced photocatalytic performance

Amorphous TiO₂ can function as an excellent hole cocatalyst to greatly improve the photocatalytic performance of a Bi₂WO₆ photocatalyst.

Visible light driven efficient photocatalytic degradation of Congo red dye catalyzed by hierarchical CuS–Bi2CuxW1−xO6−2x nanocomposite system

A series of CuS–Bi₂Cu_xW_1−xO_6−2x nanocomposite materials were prepared and evaluated as photocatalyst for degradation of Congo red dye from aqueous sources.

Electrospinning construction of Bi2WO6/RGO composite nanofibers with significantly enhanced photocatalytic water splitting activity

Bi₂WO₆/reduced graphene oxide composite nanofibers possessing significantly enhanced photocatalytic water splitting activity have been successfully fabricated.

Synthesis of Ag2CO3/Bi2WO6 heterojunctions with enhanced photocatalytic activity and cycling stability

Novel hierarchical Ag₂CO₃/Bi₂WO₆ heterojunction photocatalysts were prepared and they exhibited excellent photocatalytic activity and outstanding cycling performance for the degradation of rhodamine B (RhB) dye under visible light irradiation.

Dramatic activity of a Bi2WO6@g-C3N4 photocatalyst with a core@shell structure

Here we report a Bi₂WO₆@g-C₃N₄ core@shell structure which was prepared by a combined ultrasonication–chemisorption method with enhanced photocatalytic degradation.