A review on exploration of Fe2O3 photocatalyst towards degradation of dyes and organic contaminants

Photocatalytic degradation of tetracycline antibiotic by a novel Bi2Sn2O7/Bi2MoO6 S-scheme heterojunction: Performance, mechanism insight and toxicity assessment

Recent advances in photodegradation of antibiotic residues in water

Designing direct Z-scheme photocatalytic systems with core-shell architecture is crucial for effective charge separation towards sustainable photocatalysis. Herein, the core-shell heterojunction photocatalyst consisting of α-Fe2O3 nanoparticle layers encapsulating CeO2 nanotube arrays (Ce@Fe) was successfully synthesized through a simple and feasible strategy. The Ce@Fe heterojunctions exhibit the enhanced solar light scattering and absorption performance from 380 nm to 490 nm. The formed direct Z-scheme band structure between CeO2 and α-Fe2O3 further promotes the efficiency of carrier separation and transfer, and the core-shell nanotube array structure provides high specific surface area for antibiotic adsorption and enhanced light scattering, significantly improving the photoelectrocatalytic activity. Impressively, the unique photoelectrode achieves the highest pollutant removal efficiency of 88.6% for photoelectrocatalytic tetracycline degradation at 1 h under full light irradiation, and affords superior stability and strong alkaline resistance, which is expected to photoelectrocatalytic degrade antibiotics with high efficiency and environmental protection in harsh environment. Furthermore, the novel photoelectrocatalytic mechanism involving transfer behaviors of charge carriers, generation of reactive species, degradation intermediate products of tetracycline can be adopted after growing α-Fe2O3 layers onto CeO2 nanotube arrays, in accordance with direct Z-scheme mechanism.

Construction of core-shell heterojunction regulating α-Fe2O3 layer on CeO2 nanotube arrays enables highly efficient Z-scheme photoelectrocatalysis

Defect-engineered magnetic γ-Fe2O3 ultrathin nanosheets/mesoporous black TiO2 hollow sphere heterojunctions (γ-Fe2O3/b-TiO2) are fabricated by a metal-ion intervened hydrothermal technique and high-temperature hydrogenation, which exhibit wide-spectrum response and magnetic separation. The specific surface area, pore size and pore volume of the resultant γ-Fe2O3/b-TiO2 with hollow structure are ∼63 m2 g−1, 10.5 nm and 0.14 cm3 g−1, respectively. After surface hydrogenation, α-Fe2O3 nanosheets are converted to γ-Fe2O3 ultrathin nanosheets (∼6 nm) combined with the formation of surface defects. The ultrathin nanosheet structure facilitates the surface engineering and also favors the diffusion and transportation of photogenerated charge carriers. The apparent rate constant (k) of defect-engineered γ-Fe2O3/b-TiO2 photocatalytic degradation biotoxic tetracycline is ∼3 times higher than that of α-Fe2O3/b-TiO2 under AM 1.5 irradiation. The enhancement is attributed to the introduction of narrow bandgap unit-cell-thick γ-Fe2O3 nanosheets, the hollow structure and the defect engineering, which are beneficial to solar-light-harvesting and rapid electron transport, and spatial separation of photogenerated charge carriers. The photocatalytic degradation mechanism is also proposed. The novel magnetic γ-Fe2O3/b-TiO2 heterojunction is a promising photocatalyst for recovering the domestic sewage in environment.

Defects-engineering of magnetic γ-Fe2O3 ultrathin nanosheets/mesoporous black TiO2 hollow sphere heterojunctions for efficient charge separation and the solar-driven photocatalytic mechanism of tetracycline degradation

Surface oxygen vacancy defect-promoted electron-hole separation for porous defective ZnO hexagonal plates and enhanced solar-driven photocatalytic performance

Using solar energy to achieve seawater desalination and sewage disposal has received tremendous attention for its potential possibility to produce clean freshwater. However, the low solar-thermal conversion efficiency for solar absorber materials obstacles their practical applications. Herein, Ag nanoparticles modified floating carbon cloth (ANCC) are first synthesized via wet impregnation, photoreduction, and low-temperature drying strategy, which could float on the water and absorb the solar energy efficiently. It is worth noting that vaporization rate of ANCC with a high wide-spectrum absorption (92.39%) for the entire range of optical spectrum (200-2500 nm) is up to 1.36 kg h-1 m-2 under AM 1.5, which corresponds to solar-thermal conversion efficiency of ∼92.82% with superior seawater desalination and sewage disposal performance. Plasmon Ag promotes the conversion efficiency obviously compared to the pristine carbon cloth because the surface plasmon resonance effect could increase the local temperature greatly. After the desalination, the ion concentrations (Mg2+, K+, Ca2+, and Na+ ions) in water are far below the limit of drinking water. Such high-performance floating ANCC material may offer a feasible and paradigm strategy to manage the global water contamination and freshwater shortage problem.

Plasmon Ag-Promoted Solar-Thermal Conversion on Floating Carbon Cloth for Seawater Desalination and Sewage Disposal.

Engineering Surface N-Vacancy Defects of Ultrathin Mesoporous Carbon Nitride Nanosheets as Efficient Visible-Light-Driven Photocatalysts

Two-dimensional (2D) ultrathin mesoporous anatase TiO2 nanosheets with engineered surface defects (SDUATNs) are prepared by evaporation-induced self-assembly, solvothermal and surface hydrogenation reduction strategies. The as-prepared SDUATNs possess a comparatively large specific surface area of 100.4 m2 g−1, a main pore size of 9.7 nm, and a pore volume of 0.36 cm3 g−1. After surface hydrogenation, the narrowed bandgap of 2.97 eV expands the photoresponse from the ultraviolet to the visible-light region as a result of efficient surface defect engineering. The SDUATNs exhibit excellent photocatalytic hydrogen production performance (3.73 mmol h−1 g−1), which is about 3-fold higher than that of pristine ultrathin mesoporous anatase TiO2 nanosheets (1.31 mmol h−1 g−1) under AM 1.5G irradiation. The improvement of the hydrogen evolution performance is attributed to the efficient engineered surface defects and the special 2D ultrathin structure reducing the bandgap, increasing sunlight utilization, providing adequate surface active sites, shortening the migration distance of charge carriers and thus favoring the spatial separation of photogenerated electron–hole pairs. The high stability also favors practical applications. This work presents new insight to enhance the photocatalytic performance and may provide valuable ideas to fabricate other high-performance 2D photocatalysts.

Engineering surface defects on two-dimensional ultrathin mesoporous anatase TiO2 nanosheets for efficient charge separation and exceptional solar-driven photocatalytic hydrogen evolution

Yachao Xu

Papers

Defects-engineering of magnetic γ-Fe2O3 ultrathin nanosheets/mesoporous black TiO2 hollow sphere heterojunctions for efficient charge separation and the solar-driven photocatalytic mechanism of tetracycline degradation

Surface oxygen vacancy defect-promoted electron-hole separation for porous defective ZnO hexagonal plates and enhanced solar-driven photocatalytic performance

Plasmon Ag-Promoted Solar-Thermal Conversion on Floating Carbon Cloth for Seawater Desalination and Sewage Disposal.

Engineering Surface N-Vacancy Defects of Ultrathin Mesoporous Carbon Nitride Nanosheets as Efficient Visible-Light-Driven Photocatalysts

Engineering surface defects on two-dimensional ultrathin mesoporous anatase TiO2 nanosheets for efficient charge separation and exceptional solar-driven photocatalytic hydrogen evolution