查看更多>>摘要：Discovering an active and durable catalyst for oxygen reduction reaction is crucial to the commercialization of fuel cells, but remains grand challenging. Here we report, for the first time, the trace doping of early transition metal (ETM) Re into ultrathin PtNiGa nanowires (Re-PtNiGa NWs) to construct a novel catalyst integrating the superior activity, long-time durability, and high utilization efficiency of Pt atoms. Impressively, the Re-PtNiGa tetrametallic NWs present a 19.6-fold enhancement in mass activity (3.49 A mg(Pt)(-1)) compared to commercial Pt/C catalyst and only a 10.6% loss in mass activity after 20,000 cycles of durability test. Moreover, the real fuel cell assembled by Re-PtNiGa NWs on the cathode strongly supports its great potential in fuel cells. The density functional theory calculations reveal that introduction of ETM Re into PtNiGa NWs could weaken binding strength of oxygenated species and elevate dissolution potential, well rationalizing the great enhancements in activity and durability.
查看更多>>摘要：This study demonstrated the application of biogenic sulfidated iron (B-FeS), produced via anaerobic digestion of Desulfovibrio desulfuricans using sulfate as the terminal electron acceptor, for peroxide activation. B-FeS was assessed against chemically prepared zerovalent and sulfidated iron (ferrous sulfide and pyrite) with respect to their ability to activate peroxydisulfate (PDS) and H2O2. Regardless of the peroxide type, B-FeS outperformed benchmark iron activators in treating 4-chlorophenol due to its resistance to iron corrosion and the high content of reduced sulfur. The roles of oxidizing radicals were confirmed based on the effects of alcohol-based quenchers, multi-activity assessment, electron paramagnetic resonance spectral features, and product analysis. The pHdependent efficiency of sulfoxide-to-sulfone conversion suggested that high-valent iron species acted as the secondary oxidant in all iron/peroxide systems, and the contribution was more pronounced when PDS and B-FeS were used. Microbial sulfidation as a catalyst regeneration strategy recovered the peroxide activation capacity of oxidized B-FeS.
查看更多>>摘要：A high photogenerated carrier efficiency and a minimal recombination rate are key factors in achieving high photocatalytic efficiency. Herein, N-doped carbon (NC) nanotubes and polyaniline (PANI) fibers are compounded around Ag3PO4 nanoparticles to form a built-in electric field for electron-hole double transfer. Wrapping beta-cyclodextrin (beta-CD) around PANI fiber to isolate electron/hole composite channels is innovatively proposed. By reducing the recombination probability, more electrons can be transferred to the NC to realize a reduction of O2 to H2O2. Additionally, the encapsulation of PANI fiber by beta-CD can stabilize hole carriers, and enable phenol to be quickly transported to the confined space containing abundant hole carriers for rapid degradation. The obtained 3%CDP@Ag3PO4 @NC catalyst's charge extraction rate is twice that of Ag3PO4 and exhibits high photodegradation performance with 100% removal rate of 20 ppm phenol within 8 min under visible light, the performance of which is superior to currently Ag3PO4 based catalysts reported.
查看更多>>摘要：An efficient Na-FeMn/HZSM-5@Silicalite-1 catalyst was rationally designed for direct conversion of CO2 to aromatics. The tailor-made HZSM-5@Silicalite-1 core-shell zeolite was prepared by a facile solvent-free method. The solvent-free synthesis of core-shell zeolite could not only address pollution issues by eliminating the large utilization of organic reagents, but also exhibit a better performance for separating para-Xylene (PX) from xylenes with the assistance of capsule-like zeolite oriented synthesis. For CO2 to aromatics reaction, Na-FeMn combining with capsule-like HZSM-5@Silicalite-1 catalyst could reach 81.1% PX/X (the C-mol ratio of PX to all xylenes) ratio, which was higher than those of conventional core-shell zeolites, such as HZSM-5@SiO2 and HZSM-5@Silicalite-1 core-shell zeolites which were obtained from traditional chemical liquid deposition and hydrothermal methods. The as-synthesized zeolite paves a new route for efficient conversion of CO2 molecules into valuable PX, and provides a facile method for regulating surface acid properties of zeolite.
Lee, Dong-GyuKong, HoyoulLee, Jun HeeSong, Hyun-Kon...
9页
查看更多>>摘要：In order to realize electrochemically efficient hydrogen production, various endeavors have been devoted to developing hydrogen evolution reaction (HER) electrocatalysts having zero hydrogen binding energy (Delta G(H*) = 0) for balancing between adsorption and desorption. This work demonstrated that nitrogen doping improved the HER activity of ruthenium oxide by letting its Delta G(H*) approach zero or facilitating hydrogen desorption process. A highly nitrogen-doped ruthenium oxide catalyst guaranteeing the ruthenium-nitrogen intimacy was prepared by employing a polymer whose nitrogen-containing moiety (pyrrolidone) was strongly coordinated to ruthenium ion in the precursor solution prior to calcination. The less electronegative nature of nitrogen (when compared with oxygen) decreased the free energy uphill required for desorption of hydrogen intermediate species sitting on the nitrogen (H-*N to 1/2 H-2 + *N) to make the desorption process more favored. Also, the nitrogen dopant facilitated OH desorption from its neighboring ruthenium site (HO-*Ru + e(-) to HO- + *Ru) since the less electronegative nitrogen withdrew less electrons from the ruthenium site. The ruthenium-nitrogen intimacy of the catalyst more than doubled the electrocatalytic HER current from 33 mA cm(-2) for an undoped RuO2 to 79 mA cm(-2) for the nitrogen-doped RuO2 at -50 mV(RHE).
查看更多>>摘要：Innovative solar-driven heterostructure photocatalysts are promising for removing deleterious antibiotics residues in the water environment. Herein, we prepared a vanadium pentoxide/graphitic carbon nitride (V2O5/ C3N4) S-scheme with a facile approach. The heterostructure provides larger surface areas, promotes the separation and transfer of charge carriers, and offers abundant active sites for photocatalytic redox reactions. The composites were used to degrade amoxicillin (AMX) under solar light which attained a high removal efficiency (91.3%) and stability. Meanwhile, the photodegradation pathway of AMX was revealed by HPLC-MS/MS analysis and density functional theory (DFT) computations. Superoxide radicals evolved from conduction band of C3N4 and oxidative holes were generated from valence band of V2O5, which were confirmed by electron spin resonance experiments and selective radical quenching experiments. The V2O5/C3N4 S-scheme structure provides an internal electron channel at the interface and maintains the active sites with high potentials for photodegradation. Our work affords a robust V2O5/C3N4 S-scheme nanocomposites for sustainable water purification.
查看更多>>摘要：Persulfate-based (PS-based) advanced oxidation process is a promising technology for degradation of organic pollutants. PS activation needs efficient and economical catalysts and heterogeneous Fe-carbon composites are competitive. Herein, novel N-doped biochar-loaded nanoscale zero-valent iron (nZVI) composites (Fe@N-BC) were synthesized and evaluated for PS activation. Detailed characterization data indicated that graphitic and pyridine N structures were introduced by N-doping, which enhanced the anchoring, dispersion and loading of amorphous nZVI on biochar. Remarkably, the optimized Fe@N-BC material, Fe@N-2-BC900, presented excellent catalytic performance for PS activation for lindane removal. The N-doped defects in biochar acted as reactive bridges and accelerated the electron transfer between nZVI and PS, showing strong synergistic effects toward nZVI. O-2(center dot-) and O-1(2) were the dominant active species in catalytic systems. Additionally, Fe@N-2-BC900 catalyst showed effectiveness over a wide pH range for lindane removal. This work provides a new approach to the rational design and application of Fe@N-BC for persulfate activation in pollution control, which is certified by deep exploration of reaction mechanism.
查看更多>>摘要：The critical prerequisite for realizing the industrial application of photocatalytic technology lies on developing efficient photocatalyst through reasonable and large-scale modification strategy. Herein, the rapid and solventfree high-energy ball-milling procedure was adopted to modify graphitic carbon nitride (g-C3N4) on a large-scale by phosphorus (P) atom doping and molybdenum phosphide (MoP) decorating. It is confirmed that P doping can introduce a mid-gap state in the band gap of g-C3N4, broadening the light responsive region and enhancing the electrical conductivity of g-C3N4. The Mo-N bond at the interface of P-doped g-C3N4 and MoP acting as electrons "delivery channels" facilitates the charge transfer from P-doped g-C3N4 to MoP, while the Schottky barrier promotes the separation of photocarriers. As a result, the optimized P-doped g-C3N4/MoP photocatalyst performs an improved H-2 evolution rate of 4917.83 mu mol.g(-1).h(-1) and a favorable H-2 production stability. This work offers a replicable prototype on adopting high-energy ball-milling to modify photocatalyst.
Karamzadeh, SamirehSanchooli, EsmaelOveisi, Ali RezaDaliran, Saba...
14页
查看更多>>摘要：A mesoporous metal-organic framework with photothermal properties, namely PCN-222, was solvothermally synthesized from meso-tetra(4-carboxyphenyl)porphyrin and zirconium chloride employing both benzoic acid (BA) and trifluoroacetic acid (TFA) as modifiers. The MOF material subsequently served as a porous support for a polyoxometalate (POM), H3PW12O40, via a facile impregnation method which rendered a novel porous POM@PCN-222 composite. The solid was characterized by FT-IR, PXRD, SEM/EDX, TGA/DSC, ICP-OES, UV-Vis DRS, cyclic voltammetry (CV), and BET surface area. The one-pot synthesis of N-heterocycles (pyridine derivatives) was investigated utilizing the hybrid material via one-pot pseudo four-component reaction between aromatic aldehydes, methyl acetoacetate and ammonium acetate promoted under visible LED light irradiation in the presence of molecular oxygen as green oxidant. Products were selectively formed in good yields in the presence of the recyclable heterogeneous solid. Remarkably, POM@PCN-222 showed a superior performance for this procedure as compared to both unfunctionalized MOF and POM. The photosensitizer and photothermal properties of the porphyrin linkers combined with Lewis acidic sites derived from PW12 and Zr-6-nodes were responsible for the observed excelling performance. To understand the mechanism, control investigations, electron paramagnetic resonance (EPR) analysis and FT-IR reaction monitoring were performed. The work discloses, for the first time, a simple and environmentally friendly approach for the direct production of pyridines via one-pot thermo-photocatalytic approach using a novel POM-modified MOF in the absence of any chemical additive.
查看更多>>摘要：Herein, a g-C3N4/PDI-g-C3N4 homojunction has been fabricated for piezo-photocatalytic atrazine removal and exhibited better performance than individual photocatalysis or piezocatalysis. The introduction of PDI induces the 7C-7C interaction facilitating electrons migration, and twists the g-C3N4 plane into a more polar porous structure with enhanced piezoelectricity. The homojunction facilitates the photoelectron transfer at the g-C3N4/PDI-gC3N4 interfaces. The photoelectricity and the piezoelectricity of g-C3N4/PDI-g-C3N4 were assessed. The finite element simulation showed that the porous structure of the g-C3N4/PDI-g-C3N4 is essential to the enhanced piezoelectricity. Astonishingly, the piezo-photocatalytic atrazine degradation rate under an optimized condition (pH=2.97) reached 94% within 60 min. Moreover, the g-C3N4/PDI-g-C3N4 homojunction produced 625.54 mu M H2O2 during the one-hour piezo-photocatalysis. Given the quenching experiments, reactive species detection and the electronic band of g-C3N4/PDI-g-C3N4, the piezo-photocatalytic mechanism has been proposed. In addition, the degradation pathways and the reduced intermediates toxicity intermediates of atrazine have been investigated.
NSTL
Elsevier