Topotactic formation of poriferous (Al,C)-Ta2O5 mesocrystals for improved visible-light photocatalysis

Designing ultrathin Fe doped Ta2O5-x nanobelts for highly enhanced ammonia photosynthesis

Solar-light photosynthesis of ammonia form N2 reduction in ultrapure water over the artificial photocatalysts is attractive but still challenging compared with Haber-Bosch process. In this work, ultrathin Fe-Ta2O5-x nanobelts were fabricated via the controllable solvothermal process for ammonia photosynthesis. The formed oxygen vacancies and Fe doping narrowed their bandgap energies and promoted the carriers' separation and transfer for Fe-Ta2O5-x nanobelts. In addition, Fe doping also resulted in the reduced working functions of the samples, indicating a weaker electron binding restriction and stronger separation and transfer of photo-induced carriers. The experimental results showed that Fe-Ta2O5-x nanobelts showed remarkably enhanced photocatalytic ammonia production performance under simulated sunlight irradiation, and the relevant ammonia production rate reached approximately 3030.86 μM g-1 h-1, which was 9.63 times of pristine Ta2O5-x and 491.0 times of commercial Ta2O5, and a relatively stable photocatalytic ammonia production performance under simulated sunlight irradiation for Fe-Ta2O5-x nanobelts. Meanwhile, it was also found that Fe doping has great influences on the photocatalytic performance under visible light and simulated sunlight irradiation, mainly because of their suitable bandgap energies and enhanced solar-light harvesting capacity. Current work indicates the great potentials of ultrathin tantalum-based functional materials for high-efficiency ammonia photosynthesis.

Designing step-scheme AgI decorated Ta2O5-x heterojunctions for boosted photodegradation of organic pollutants

Step-scheme (S-scheme) AgI decorated Ta2O5-x heterojunctions have been designed and synthesized via a combination of solvothermal and chemical deposition methods for enhanced visible-light harvesting and high-performance photocatalysis. The AgI nanoparticles showed great influences on the visible-light absorption and charge separation between AgI and Ta2O5-x microspheres. The experimental results indicated that the as-prepare AgI/Ta2O5-x composites achieved enhanced photocatalytic performance towards tetracycline degradation under visible light, and the AgI/Ta2O5-x-11 sample displayed the highest photocatalytic performance and the maximum rate constant of approximately 0.09483 min-1, which was 7.22 times that of Ta2O5-x microspheres and 2.56 times that of AgI, respectively. The highly enhanced photocatalytic performance was mainly attributed to the construction of S-scheme heterostructure and formation of oxygen vacancies in Ta2O5-x microspheres. In addition, the trapping experimental and DMPO spin-trapping ESR spectra confirmed the ⸱O2- and ⸱OH species as the main radicals during tetracycline degradation. Current work indicates an S-scheme tantalum-based composites for high-performance environmental photocatalysis.

Green synthesis of rectangular hollow tubular carbon nitride via in-situ self-assembly strategy to enhance the degradation of tetracycline hydrochloride under visible light irradiation

It has been an urgent requirement for materials with remarkable performance in the photocatalytic degradation of organic contaminants by photocatalytic technology. Limited surface area and speedy recombination rate of photogenerated charge carriers seriously restrain the application of g-C3N4. Morphology control is a powerful approach to enhance the photocatalytic efficiency of g-C3N4. Herein, we reported a method to attain graphitic carbon nitride with rectangular hollow tubular morphology and asperous surface (TUM-CN-2) which is prepared from urea-melamine hydrothermal products and trithiocyanuric acid by self-assembling without using organic solvents or template agents. The specific surface area, photocatalytic activity, and photo-generated carriers migration and separation rate of the obtained photocatalyst TUM-CN-2 are vastly improved. Contrasted with pure g-C3N4, the degradation rate of tetracycline hydrochloride (TCH) and Rhodamine B (RhB) was enhanced about 3.04 and 13.96 times in visible light irradiation, respectively. Moreover, the interference parameters, active free radicals, potential degradation mechanism, and degradation paths of TCH were researched systematically. This work provides a green way to acquire the modified g-C3N4 with splendid catalytic activity through the self-assembly method.

Rational design of S-scheme AgI/ZrTiO4-x heterojunctions for remarkably boosted norfloxacin degradation

Emerging S-scheme heterojunction photocatalysts endowed with efficient charge separation and strong redox capacity have stimulated wide interests in dealing with environmental issues nowadays. In this work, we firstly fabricated the oxygen vacancy modified ZrTiO_4-x nanocrystals, which was further combined with AgI to build the defective S-scheme AgI/ZrTiO_4-x heterojunctions for visible-light photocatalytic norfloxacin degradation. The synthesized ZrTiO_4-x nanocrystals and AgI/ZrTiO_4-x heterojunctions displayed remarkably boosted norfloxacin degradation performance under visible-light irradiation. The reaction rate constant of the optimized AgI/ZrTiO_4-x-5% heterojunction is as high as 0.01419 min^-1, which is approximately 43.35 times that of AgI and 7.93 times that of ZrTiO_4-x nanocrystals, and far superior to those of commercial TiO₂ and commercial ZrO₂. The high-performance photocatalytic norfloxacin degradation could be mainly attributed to the formation of S-scheme charge transfer pathways and oxygen vacancy defects. More significantly, AgI/ZrTiO_4-x could also realize the effective photo-decomposition of other emerging pollutants. Finally, the visible-light photocatalytic performance and photocatalysis mechanism were investigated.

Designing oxygen vacancy mediated bismuth molybdate (Bi2MoO6)/N-rich carbon nitride (C3N5) S-scheme heterojunctions for boosted photocatalytic removal of tetracycline antibiotic and Cr(VI): Intermediate toxicity and mechanism insight

Polymeric N-rich carbon nitride of C₃N₅ is being utilized as a new visible-light-driven catalyst due to its narrower bandgap (∼2.0 eV). Building step-scheme (S-scheme) heterojunction by coupling with other semiconductors especially those own oxygen vacancies (OVs) can further upgrade the photocatalytic performance of C₃N₅-based photocatalysts. Herein, a novel S-scheme heterojunction of OVs mediated Bi₂MoO₆/C₃N₅ was fabricated by in-situ growing Bi₂MoO₆ nanoparticles with OVs on C₃N₅ nanosheets. Benefiting from the efficient separation and transfer of high energetic charge carriers by S-scheme charge migration, enriched structural defects, as well as the close contact by the in-situ growth, the heterojunction exhibited superior visible-light photocatalytic performance toward the removal of tetracycline (TC) and Cr(VI) than C₃N₅, Bi₂MoO₆, and their mechanical mixture under visible light. The TC degradation routes and the bio-toxicity evolution of TC were explored. Moreover, the photocatalytic mechanism for TC decomposition and Cr(VI) reduction over Bi₂MoO₆/C₃N₅ with OVs were elucidated. This work presents a newfangled vision for designing promising C₃N₅-based S-scheme heterojunction photocatalysts for pollution control.

Construction of Au and C60 quantum dots modified materials of Institute Lavoisier-125(Ti) architectures for antibiotic degradation: Performance, toxicity assessment, and mechanistic insight

High-performance and stabilized photocatalytic degradation of antibiotic contaminants still remains a challenge in environmental photocatalysis and has been studied worldwide. In this work, hybrid Au and C60 quantum dots decorated Materials of Institute Lavoisier-125(Ti) (MIL-125(Ti)) composites were successfully fabricated for visible-light photocatalytic tetracycline degradation with pristine MIL-125(Ti) as a comparison. The experimental results revealed that the introduction of C60 quantum dots and Au nanoparticles resulted in highly enhanced visible-light harvesting and charge separation for efficient tetracycline degradation. The optimal Au/C60-MIL-125(Ti)-1.0% sample exhibited the highest visible-light photocatalytic performance, and the corresponding rate constant was approximately 9.19 times of MIL-125(Ti), indicating the significant roles of Au and C60 quantum dots in boosting visible-light absorption and charge separation. Furthermore, the radical species, possible degradation pathways and toxicity assessment, and photocatalytic mechanism were also investigated. Current work indicates a synergistic strategy for enhancing visible-light harvesting and charge separation to fabricate high-performance composite photocatalysts.

In situ construction of a C3N5 nanosheet/Bi2WO6 nanodot S-scheme heterojunction with enhanced structural defects for the efficient photocatalytic removal of tetracycline and Cr(vi)

A novel 2D/0D C3N5/Bi2WO6 S-scheme heterojunction with enhanced structural defects has been designed for the efficient elimination of pharmaceutical antibiotics and Cr(vi).