A novel g-C3N4/PDI@MOF heterojunction was synthesized by the in situ growth of NH2-MIL-53(Fe) onto the g-C3N4/PDI layer. The heterojunction was applied as a photocatalyst for the removal of pharmaceutical and phenolic micropollutants in the present of H2O2 and visible LED light (420

Construction of g-C3N4/PDI@MOF heterojunctions for the highly efficient visible light-driven degradation of pharmaceutical and phenolic micropollutants

N-Doped carbon nanotubes encapsulating bimetallic Fe/Mn nanoparticles (FeMn@NCNTs) were fabricated after a one-step pyrolysis and were used as the catalyst for peroxymonosulfate activation to degrade acetamiprid. The FeMn@NCNTs showed uniform nanotubes with rich N doping and the encapsulated FeMn nanoparticles were doubly protected by both NCNTs and a clingy graphitic structure. The results indicated that the confined FeMn nanoparticles were designated as Fe2.7Mn0.3C according to the XRD pattern and elemental composition. Radical quenching indicated that SO4˙− and ˙OH were the dominant radicals in the FeMn@NCNTs/PMS system. The indispensable roles of both radical pathways of O2˙− and non-radical 1O2 in the superior catalytic performance were also confirmed. As a result, both the embedded FeMn nanoparticles and NCNTs in FeMn@NCNTs contributed to the acetamiprid degradation with multiple degradation mechanisms. XPS results confirmed the formation of redox cycles between the multiple valence states of Mn and Fe, which ensured the superior catalytic activity of FeMn@NCNTs for PMS activation. In addition, only a small decrease in the catalytic performance from 99.5% to 90% was observed after four cycles. The catalytic activity of used FeMn@NCNTs was mostly recovered after heat regeneration (350 °C), which exhibited the excellent stability and reusability of the FeMn@NCNTs.

Fe/Mn nanoparticles encapsulated in nitrogen-doped carbon nanotubes as a peroxymonosulfate activator for acetamiprid degradation

The abolition of environmental pollutants and production of hydrogen (H2) from water using a heterogeneous photocatalyst is a demanding science of the current scenario to solve the increasing environmental pollution and worldwide energy catastrophe in modern life. To validate this purpose, the design of low-cost and durable semiconductor-based photocatalysts with great light absorption capacity becomes the most challenging issue for researchers. Regarding this, herein the phosphotungstic acid (HPW)-anchored Zr6O4(OH)4(BDC)6 (UiO-66) metal-organic framework (MOF), i.e., HPW@UiO-66, has been prepared by a hydrothermal method and is efficient, stable, and capable of harvesting solar energy toward the degradation of tetracycline hydrochloride (TCH) and H2 production in the presence of a sacrificial donor. The ionic interaction between HPW and UiO-66 plays a key role toward the photostability and charge-transfer mechanism of the composite and is well characterized with X-ray diffraction, UV diffuse-reflectance spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. A total of 30 wt % HPW@UiO-66 shows a maximum degradation of about 87.24% of a 20 ppm TCH solution in 60 min of solar-light irradiation and about 353.89 μmol/h of H2 production. The conduction- and valence-band potentials are well characterized with Mott-Schottky measurement and a delay charge recombination process through electrochemical impedance spectroscopy. The proposed mediator-free Z-scheme-oriented electron-hole migration route is well supported by photoluminescence, and the scavenger test well explains the better charge-carrier separation and high catalytic performance of the prepared composite. This research will bestow an advantageous blueprint to fabricate novel and challenging photocatalysts toward the photocatalytic treatment of environmental pollutants and H2 evolution.

HPW-Anchored UiO-66 Metal-Organic Framework: A Promising Photocatalyst Effective toward Tetracycline Hydrochloride Degradation and H2 Evolution via Z-Scheme Charge Dynamics.

Conjugated porous polymers (CPPs) have recently emerged as a new class of visible light-active, organic and heterogeneous photocatalysts for visible light-mediated photoredox reactions. The CPPs have been established as a potential alternative to resolve critical drawbacks of traditional molecular and homogeneous photocatalysts due to their structural durability, non-toxicity, low cost due to the absence of noble metals, and high designability. Tremendous attempts have been made toward the design and synthesis of CPPs for a variety of visible light-promoted photocatalytic chemical transformations. Nevertheless, the concomitant design protocols of CPPs have not been well structured so far. Herein, in this review, we aim to summarize the recent developments in controlling the structural, photophysical and electronic properties of CPPs, and thereby extract the underlying design principles. According to the principle of the photocatalytic process, key parameters for the molecular design of CPPs were described in three sections: (1) light absorbance by energy band gap, (2) charge separation and transport, and (3) electron transfer to the target substrate. The macroscopic features, i.e. morphology, porosity and chemical functionality, and processibility of CPPs were also presented for the enhancement of their photocatalytic activity.

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Designing conjugated porous polymers for visible light-driven photocatalytic chemical transformations

Methane activation and utilization are among the major challenges of modern science. Methane is potentially an important feedstock for manufacturing value-added fuels and chemicals. However, most known processes require excessive operating temperatures and exhibit insufficient selectivity. Here, we demonstrate a photochemical looping strategy for highly selective stoichiometric conversion of methane to ethane at ambient temperature over silver–heteropolyacid–titania nanocomposites. The process involves a stoichiometric reaction of methane with highly dispersed cationic silver under illumination, which results in the formation of methyl radicals. Recombination of the generated methyl radicals leads to the selective, and almost quantitative, formation of ethane. Cationic silver species are simultaneously reduced to metallic silver. The silver–heteropolyacid–titania nanocomposites can be reversibly regenerated in air under illumination at ambient temperature. The photochemical looping process achieves a methane coupling selectivity of over 90%, a quantitative yield of ethane of over 9%, high quantum efficiency (3.5% at 362 nm) and excellent stability. Activating methane at ambient temperature is challenging due to its stability, but could ultimately give access to a variety of other fuels and chemicals. Here, the authors present a photochemical looping strategy based on silver chemistry that converts methane to ethane under illumination at room temperature.

/pdf/stoichiometric-methane-conversion-to-ethane-using-4im5w26g9p.pdf

Stoichiometric methane conversion to ethane using photochemical looping at ambient temperature

A series of H3PW12O40 (HPW)-containing polyimide (PI) hybrid composites (TPI) are prepared through in-situ solid-state polymerization using HPW, melem and pyromellitic dianhydride as precursors. The effect of HPW on the morphology, porosity, chemical structure, and optical and visible-light photocatalytic degradation efficiency of TPI composites are systematically investigated by various characteristic methods. By comparing the structure, property and photocatalytic activity of the TPI composites and the HPW-PI composites (prepared by the impregnation method), it indicates that HPW can promote the formation of C N bond in the five-membered imide rings between amines and anhydrides during the in-situ solid-state condensation process. Subsequently, the visible-light (λ > 400 nm) photocatalytic degradation efficiency of imidacloprid on TPI composites is also enhanced compared with the pristine PI because of the enhancement of the in-situ solid-state condensation reaction, photogenerated electron-hole separation efficiency and visible-light utilization efficiency after the introduction of HPW. The visible-light photocatalytic degradation rate constant k of 15% TPI composites prepared at 300 °C and 5% TPI composites prepared at 325 °C are about 10.33 and 2.42 times of the corresponding pristine PI, respectively. Compared with commercial P25, the photocatalytic degradation efficiency of 15% TPI-300 and 5% TPI-325 are about 4.58 and 5.13 times of P25 under visible light irradiation.

Positive effects of phosphotungstic acid on the in-situ solid-state polymerization and visible light photocatalytic activity of polyimide-based photocatalyst

Extended light absorption and enhanced visible-light photocatalytic degradation capacity of phosphotungstate/polyimide photocatalyst based on intense interfacial interaction and alternate stacking structure

Junhao Huang

Papers

Positive effects of phosphotungstic acid on the in-situ solid-state polymerization and visible light photocatalytic activity of polyimide-based photocatalyst

Extended light absorption and enhanced visible-light photocatalytic degradation capacity of phosphotungstate/polyimide photocatalyst based on intense interfacial interaction and alternate stacking structure

In-situ solid phase thermal transformation of self-assembled melamine phosphotungstates produce efficient visible light photocatalysts.

Compensation of magnesium by residual carbon impurities in p-type GaN grown by MOCVD

Boosting Light Harvesting and Charge Separation in 3d Porous Ws2@C@Znin2s4 Skeleton Heterojunction for Efficient Solar Fuels Production