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This work reports the effective preparation of a bimetallic metal–organic framework CoNi-MOF@MoS2 core–shell Z-scheme heterojunction photocatalyst via a two-step hydrothermal method. MoS2 nanoflowers uniformly grow on the multilayer CoNi-MOF exterior. MoS2 can be added to the system to improve its specific surface area and provide enough surface active sites for photocatalysis. The resultant CoNi-MOF@MoS2 has a broad-spectrum response, which is favorable for promoting the photocatalytic process. Under visible light irradiation, CoNi-MOF@MoS2 has a high hydrogen evolution efficiency of 478.6 μmol h−1 g−1. It also activates peroxymonosulfate, and the photocatalytic degradation rate of RhB pollutants in water can be up to 99.3% within 40 min, which is several times higher than that of the CoNi-MOF. The presence of the distinctive core–shell Z-scheme heterojunction structure is responsible for efficient charge separation and the enhanced photocatalytic performance. The high stability of CoNi-MOF@MoS2 also implies its potential applications in fields of environment and energy in future. [ABSTRACT FROM AUTHOR]

Interface engineering is vital for promoting photocatalytic performance. Here, a novel Zr-based metal–organic framework PCN-222@defective ZnIn2S4 with indium vacancy core–shell Z-scheme heterojunctions (PVIn-ZIS) was fabricated through a facile solvent-thermal method. The as-synthesized PVIn-ZIS showed a superior photocatalytic behavior than those of ZnIn2S4 with/without indium vacancies and PCN-222@ZnIn2S4 without indium vacancies. The structure of the material was characterized and analyzed by X-ray diffractometry, in situ X-ray electron spectrometry, electron paramagnetic resonance, etc. The optimized photocatalytic H2 production rate of the material was up to 1.79 mmol g−1 h−1, several times higher than that of others. Furthermore, the photocatalytic degradation efficiency of tetracycline could reach 93.50% within 4 h. The enhancement in the photocatalytic performance could be ascribed to the formation of Z-scheme heterojunction among PCN-222 and ZnIn2S4 with indium vacancy promoting the spatial charge separation. The scarcely decreased photocatalytic performance after recycling indicated the high stability of PVIn-ZIS, which will be potentially applied in fields of energy and the environment. [ABSTRACT FROM AUTHOR]

Reasonable design of heterojunction photocatalysts can effectively promote charge separation, thus improving their photocatalytic performance. Herein, a Bi2Fe4O9@ZnIn2S4 S-scheme laminated heterojunction photocatalyst with 2D/2D interface interaction is prepared via a hydrothermal–annealing–hydrothermal method. The photocatalytic hydrogen production rate of Bi2Fe4O9@ZnIn2S4 is up to 3964.26 μmol h−1 g−1, which is 12.1 times higher than that of pristine ZnIn2S4. In addition, its photocatalytic tetracycline degradation efficiency (99.9%) is also optimized. The enhanced photocatalytic performance can be attributed to the formation of S-scheme laminated heterojunctions that facilitate charge separation as well as strong 2D/2D laminated interface interactions favoring charge transfer. By combining in situ irradiation X-ray photoelectron spectroscopy with other characterization methods, the photoexcited charge transfer mechanism of S-scheme heterojunctions has been proved. Photoelectric chemical tests demonstrate the effectiveness of the S-scheme laminated heterojunction in improving the charge separation. This strategy provides a novel perspective for designing other high-efficient S-scheme laminated heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Na-doped g-C3N4/NiO 2D/2D laminated p–n heterojunction nanosheets are fabricated by facile calcination and hydrothermal methods. The average thickness of g-C3N4 nanosheets is ∼1.388 nm, and the ultrathin structure allows for a high specific surface area and enough surface active sites, increasing the surface reactivity. The flower ball like structure of NiO increases the light utilization rate. Na doping accelerates charge separation and transport by increasing the electrical conductivity. The g-C3N4 and NiO nanosheets form 2D/2D laminated structures, and the spherical structure can suppress the agglomeration of 2D nanosheets, which could realize adequate interface contact and form efficient p–n heterojunctions. The p–n heterostructure builds an internal electric field to accelerate spatial charge separation. Under visible light irradiation, the photocatalytic degradation efficiency for ciprofloxacin and the hydrogen production rate of Na-doped g-C3N4/NiO are up to 99.0%, and 2299.32 μmol h−1 g−1, respectively, which are several times higher than those of the pristine one. The fabrication strategy for 2D/2D laminated heterojunctions may provide new insights for the preparation of novel laminated photocatalysts with high performance. [ABSTRACT FROM AUTHOR]

A hollow polyhedral structure can effectively capture light and facilitate carrier separation, thus enhancing photocatalytic performance. Herein, hollow cubic CdS@CoS/WS2 dual S-scheme heterojunction superstructure photocatalysts are fabricated using a simple sulfidation and hydrothermal method. CdS@CoS/WS2 with a band gap of 1.59 eV and a relatively narrow band gap broadens the photoreaction to the near-infrared region and shows a good photothermal effect, which can promote photocatalytic reactions. It shows a relative specific surface area of 91.58 m2 g−1, which provides abundant surface-active sites to enhance the photocatalytic reaction. Under light conditions, the photocatalytic degradation ratios of CdS@CoS/WS2 for tetracycline and bisphenol A are up to 98.9 and 99.1%, and the hydrogen evolution efficiency is also up to 10.62 mmol h−1 g−1. The enhanced photothermal–photocatalytic performance could be due to the formation of a dual S-scheme heterojunction superstructure that facilitates space charge separation, a narrow band gap and a mesoporous hollow structure promoting solar light utilization, providing abundant surface-active sites and enhanced mass transfer. This simple strategy provides a new idea for the construction of high-performance hollow superstructure photocatalysts. [ABSTRACT FROM AUTHOR]

Sono-photocatalysis is considered a promising strategy for water decontamination and hydrolysis, and it is crucial to improve the sensitivity of the catalyst to mechanical forces to obtain more energy. In a single photocatalyst, the hollow structure refracts sunlight many times to improve light utilization, but with a sono-photocatalyst, can the hollow structure refract sound waves to enhance the sound field energy? This paper reports formation of CdS with different structures by controlling the etching rate and wrapping with hollow defective CoNi-LDH (HD-CoNi-LDH) to form a bilayer porous hollow framework structure. Characterization confirmed that evolution of CdS from the solid gave the bilayer a hollow framework state and improved the degree of sound field energy absorption. It was further shown that the honeycomb-like porous structure of HD-CoNi-LDH enhanced sound field energy absorption, which then acted on CdS to enable piezoelectric photocatalysis. Specifically, strong sound field absorption by hollow CdS@HD-CoNi-LDH increased the hydrogen precipitation rate by 3.5 times and the degree of bisphenol A degradation by approximately 30% compared to solid CdS. This work provides a new perspective for sono-photocatalysis. [ABSTRACT FROM AUTHOR]

Flower-ball-like ZnIn2S4@hollow dodecahedral polyoxometalate (K3PW12O40)@flower-shell-like ZnIn2S4/Ag2S yolk@shell dual Z-scheme superstructure tandem heterojunction nanoreactors are fabricated through a two-step hydrothermal method combined with a cation exchange strategy. Hollow dodecahedral K3PW12O40 acts as a bridge to form the special yolk@shell dual Z-scheme superstructure tandem heterojunction between two types of ZnIn2S4. Due to the encapsulation and confinement effects of the nanoreactors, the size of flower-ball-like ZnIn2S4 in hollow dodecahedral K3PW12O40 is limited to form a yolk@shell structure, which favors light multi-reflection. The surface plasmon resonance (SPR) effect of Ag2S nanoparticles extends the photoresponse to visible light and near-infrared regions. The resultant tandem heterojunction nanoreactors exhibit excellent photocatalytic degradation of tetracycline hydrochloride (∼99%) and hydrogen evolution (2107.3 μmol h−1 g−1) performance, which are several times higher than those of the pristine one. This is ascribed to the formation of a dual Z-scheme tandem heterojunction favoring spatial charge separation, the SPR of Ag2S and yolk@shell hollow structure benefiting light utilization and mass transfer, and the encapsulation and confinement effects of the special nanoreactors facilitating the complete catalytic reaction and stability. This work provides an efficient strategy for constructing highly efficient tandem heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Herein, C,N co-doped porous TiO2 hollow sphere visible light photocatalysts were fabricated using biocompatible N-lauroyl-l-glutamic acid as a doped precursor and soft-template by a mild and facile self-assembly soft-template method, followed by calcination at 550 °C in air. The structure, morphology, and surface elemental composition were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the prepared TiO2 photocatalysts have a porous hollow sphere structure and are co-doped with C and N. The visible-light-driven photocatalytic degradation rates of phenol and 2-chlorophenol are ∼92 and 90%, respectively. The photocatalytic reaction rate constants of phenol and dichlorophen on HPT550 porous TiO2 hollow spheres were about ∼4 and ∼2 times higher than those on P25, respectively. This enhancement is because the C,N co-doped porous TiO2 hollow spheres not only extend the photoresponse to the visible light region as C,N co-doping narrows the bandgap (2.7 eV), but also expose a large number of surface active sites that favor visible-light-driven photocatalysis. Moreover, the porous hollow structure favors multiple reflections of photons in the interior, increasing the utilization ratio of light. It is worth to pay more efforts to the development of visible light photocatalysts and further promote their practical application. [ABSTRACT FROM AUTHOR]

Reasonable design of heterojunction photocatalysts can effectively promote charge separation, thus improving their photocatalytic performance. Herein, a Bi 2 Fe 4 O 9 @ZnIn 2 S 4 S-scheme laminated heterojunction photocatalyst with 2D/2D interface interaction is prepared via a hydrothermal-annealing-hydrothermal method. The photocatalytic hydrogen production rate of Bi 2 Fe 4 O 9 @ZnIn 2 S 4 is up to 3964.26 μmol h -1 g -1 , which is 12.1 times higher than that of pristine ZnIn 2 S 4 . In addition, its photocatalytic tetracycline degradation efficiency (99.9%) is also optimized. The enhanced photocatalytic performance can be attributed to the formation of S-scheme laminated heterojunctions that facilitate charge separation as well as strong 2D/2D laminated interface interactions favoring charge transfer. By combining in situ irradiation X-ray photoelectron spectroscopy with other characterization methods, the photoexcited charge transfer mechanism of S-scheme heterojunctions has been proved. Photoelectric chemical tests demonstrate the effectiveness of the S-scheme laminated heterojunction in improving the charge separation. This strategy provides a novel perspective for designing other high-efficient S-scheme laminated heterojunction photocatalysts.

Herein, C,N co-doped porous TiO2 hollow sphere visible light photocatalysts were fabricated using biocompatible N-lauroyl-l-glutamic acid as a doped precursor and soft-template by a mild and facile self-assembly soft-template method, followed by calcination at 550 °C in air. The structure, morphology, and surface elemental composition were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the prepared TiO2 photocatalysts have a porous hollow sphere structure and are co-doped with C and N. The visible-light-driven photocatalytic degradation rates of phenol and 2-chlorophenol are ∼92 and 90%, respectively. The photocatalytic reaction rate constants of phenol and dichlorophen on HPT550 porous TiO2 hollow spheres were about ∼4 and ∼2 times higher than those on P25, respectively. This enhancement is because the C,N co-doped porous TiO2 hollow spheres not only extend the photoresponse to the visible light region as C,N co-doping narrows the bandgap (2.7 eV), but also expose a large number of surface active sites that favor visible-light-driven photocatalysis. Moreover, the porous hollow structure favors multiple reflections of photons in the interior, increasing the utilization ratio of light. It is worth to pay more efforts to the development of visible light photocatalysts and further promote their practical application.

A macro/mesoporous anatase TiO2 ceramic floating photocatalyst has been successfully synthesized using highly thermally stable mesoporous TiO2 powder as a precursor, followed by a camphene-based freeze-casting process and high-temperature calcinations. The ceramics are characterized in detail by X-ray diffraction, Raman spectra, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption isotherms. The results indicate that the TiO2 ceramics present hierarchical macro/mesoporous structures, which maintain high porosity and high compressive strength at the optimal sintering temperature of 800 °C. The ordered mesoporous TiO2 network still possesses high thermal stability and inhibits the anatase-to-rutile phase transformation during calcinations. The obtained ceramics exhibit good adsorptive and photocatalytic activity for the degradation of octane and rhodamine B, and the total organic carbon removal ratio is up to 98.8% and 98.6% after photodegradation for 3 h, respectively. The roles of active species in the photocatalytic process are compared using different types of active species scavengers, and the degradation mechanism is also proposed. Furthermore, the ceramics are recyclable, and no clear changes are observed after ten cycles. In addition, the ceramics are also active in the photodegradation of phenol, thiobencarb, and atrazine. Therefore, these novel floating photocatalysts will have wide applications, including the removal of floating organic pollutants from the wastewater surfaces or the removal of soluble organic pollutants from wastewater.