Electron Spin Resonance Measurements Research Articles

A facile synthesis of Cu(II) diethyldithiocarbamate from monovalent copper-cysteamine and disulfiram

An efficient, atom-economic synthesis of Cu(II) diethyldithiocarbamate from a monovalent copper-cysteamine and disulfiram was developed. • An efficient and atom-economic synthesis of Cu(DDC)2 from DSF and monovalent copper cysteamine (CuCy) is reported. • The chemical structure, proposed reaction mechanism and the optimal reaction conditions were investigated. • The photochemical reactions of Cu(DDC) 2 in five solvents and the possible reaction mechanism were discussed. The copper(II) diethyldithiocarbamate (Cu(DDC) 2 ) complex prepared from disulfiram and Cu(II) species has shown excellent anticancer activity. However, general synthetic methods largely rely on tedious procedures and limited reaction types with undesirable by-products. In this paper, we reported an efficient and atom-economic synthesis of Cu(DDC) 2 from disulfiram and monovalent copper cysteamine (Cu(I)Cy) via a one-step oxidation–reduction reaction. Cu(DDC) 2 was fully characterized by nuclear magnetic resonance (NMR), mass spectrometry (MS), infrared spectroscopy (IR), scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet and visible (UV–Vis) spectrophotometry, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and single crystal X-ray diffraction. The proposed reaction mechanism and the effect of reaction conditions on the Cu(DDC) 2 synthesis were investigated. The photochemical reactions of Cu(DDC) 2 was studied in acetone, DMF, toluene, CCl 4 , CHCl 3 under 254, 365 nm alone or combined 254 & 365 nm irradiation based on UV–vis and EPR measurements. The photolysis rate followed in this order: CCl 4 > CHCl 3 > DMF > toluene > acetone. The final photolysis products in CHCl 3 were DSF and Cu 2 (DDC) 2 Cl 2 .

Intermolecular interactions of tetracyanoethylene (TCNE) and fumaronitrile (FN) with minor amines: A combined UV-Vis and EPR study.

In this paper, the nature of interactions between two cyanocarbons-tetracyanoethylene (TCNE) and fumaronitrile (FN)-and a series of four secondary amines possessing a general formula C4HxN (x = 5-11) is thoroughly scrutinized. For all of the TCNE-amine pairs, tricyanovinylation (TCV) reaction is observed; however, only for pyrrole, it is accompanied with a visible charge-transfer (CT) complex formation-no such chemical individuals, characteristic for TCNE, have been noticed for aliphatic and alicyclic amines. On the contrary, FN forms such complexes with all the amines studied. Interestingly, a rather unexpected reaction of FN with alicyclic amines has been observed. The recorded electron paramagnetic resonance (EPR) spectra indicate the presence of both TCNE●- and FN●- radicals in the analyzed samples, assigned to a complete charge (electron) transfer process within the CT complexes, whose efficiency can be additionally enhanced by photoirradiation. The origination of the former radical, whose presence is observed also in the TCNE-diethylamine mixture, is as well proposed to result indirectly from the TCV reaction, occurring for this system. Finally, the superhyperfine structure of EPR spectra, indicating the existence of some secondary interactions of the radicals with surrounding compounds, is discussed. Formation of CT complexes and tricyanovinylates has been investigated and characterized with UV-Vis spectroscopy, while the presence of (cyano)radicals in the analyzed mixtures has been evidenced by (photoinduced) EPR measurements. Interpretation of the experimental results is also supplemented with computer simulations including density functional theory calculations.

Understanding the selectivity trend of water and sulfate (SO42−) oxidation on metal oxides: On-site synthesis of persulfate, H2O2 for wastewater treatment

Herein, H2O2 production activity via two-electron water oxidation reaction is identified on metal oxides (WO3, TiO2, and BiVO4) in acidic SO42− involving electrolyte, in which persulfate (PS) acts as an intermediate. A deep understanding of mechanism of PS production reaction on metal oxides has been realized based on rigorous crystal plane analysis of WO3 and TiO2 by combining density functional theory calculations and zeta potential measurements. It is found that the binding-energy of adsorbed hydroxyl groups on dominant exposed crystal plane of WO3 is lower than that of TiO2, leading to more SO42− adsorption sites at the surface of WO3. Consequently, the formation of PS on WO3 surface is more favorable. Meanwhile, both SO4−· and OH· were detected in the electrolyte by electron paramagnetic resonance measurement, which play a crucial role in organic pollutants wastewater treatment, with a degradation efficiency of 96% in 90 min for a typical pollutant norfloxacin. This work can provide a novel insight for understanding the selectivity of water and SO42− species oxidation on metal oxides, and open a new way for both on-site H2O2 production and advanced oxidation processes application.

FeN4-doped carbon nanotubes derived from metal organic frameworks for effective degradation of organic dyes by peroxymonosulfate: Impacts of FeN4 spin states

• FeN 4 -doped carbon nanotubes by ball milling and pyrolysis of ZIF-8 and MIL-101. • D 2 -FeN 4 the main active site in PMS activation. • 1 O 2 the major active species in the degradation of organic pollutants. • Minor contributions from • OH and SO 4 ∙ - radicals to pollutant degradation. Development of low-cost, high-performance catalysts for the effective degradation of organic dyes is of both fundamental and technological significance for environmental remediation. Herein, FeN 4 -doped carbon nanotubes exhibit a remarkable catalytic activity towards the degradation of acid orange 7 (AO7) in the presence of peroxymonosulfate (PMS). This is accounted for by the abundant well-dispersed FeN 4 sites and appropriate adsorption energy. Radical quenching experiments and electron paramagnetic resonance measurements suggest that singlet oxygen is the main reactive oxygen species. 57 Fe Mossbauer spectroscopy measurements show that the FeN 4 moieties contain multiple spin states, and in conjunction with density functional theory calculations, confirm that FeN 4 with a low/medium spin state serves as the key sites for PMS activation and hence AO7 degradation. Results from this study highlight the critical role of spin states in FeN 4 in the generation of singlet oxygen for effective degradation of organic pollutants.

Highly dispersed and stable Fe species supported on active carbon for enhanced degradation of rhodamine B through peroxymonosulfate activation: Mechanism analysis, response surface modeling and kinetic study

Herein, highly dispersed Fe species supported on activated carbon (CA-Fe-C) was fabricated with the aid of citric acid, showing excellent catalytic performance and stability for the degradation of rhodamine B (RhB) through peroxymonosulfate (PMS) activation. The radical quenching study, electron paramagnetic resonance (EPR) measurement and PMS consumption analysis confirmed the RhB degradation mechanism involving reactive radical species attacking RhB and non-radical oxidation pathway. The main degradation intermediates were identified by LC-MS, and the possible RhB degradation pathways were deduced. A multivariate quadratic polynomial model was developed using the response surface methodology (RSM) to examine how the removal of RhB was influenced by several quantifiable factors, with the objective of optimizing RhB removal. The analysis of variance (ANOVA) was used to evaluate the adequacy and significance of the proposed model. The effects of solution pH values, initial concentration, inorganic anions, PMS dosage, catalyst dosage, and metal loading amount on RhB removal were investigated. The method of initial rates was employed to determine the intrinsic reaction rate law, and the reaction was identified to follow the Langmuir-Hinshelwood (L-H) kinetics model.

Stable electronic structure related with Mn4+[sbnd]O−• coupling determines the anomalous nonhysteretic behavior in Na2Mn3O7

Oxygen redox is a double-edged sword for battery cathodes as it furnishes a substantial increase in energy density at the expense of bringing additional detrimental issues, such as irreversible local structural transformation and substantial voltage hysteresis. Intriguingly, Na2Mn3O7 can access an oxygen-redox capacity with an abnormal small voltage hysteresis (∼0.05 V), making it a rare model system to identify a reaction mechanism that suitable for engineering oxygen-redox cathodes with high energy efficiency. Herein, we firstly corroborate by operando electron paramagnetic resonance (EPR) that the local electronic structure evolution of Na2Mn3O7 upon oxygen redox is highly reversible. By ex situ low-temperature EPR measurements, we also confirm that O 2p localized holes (O−•) is the chemical state of oxidized oxygen species in Na2-xMn3O7, contributing to a highly reversible local structural evolution around Na nucleus. The stable electronic structure stimulated by the absence of in-plane Mn migration and the dispersive oxygen redox without OO dimerization in Na2-xMn3O7, is thus firstly proposed as the origin of abnormal small voltage hysteresis. This study provides the rationale for achieving nonhysteretic behavior in the large family of oxygen-redox cathodes.

Novel CoFe2Px derived from CoFe2O4 for efficient peroxymonosulfate activation: Switching the reaction route and suppressing metal leaching

In this study, bimetallic phosphides were reported to be novel, efficient, and stable activators of peroxymonosulfate (PMS). CoFe2Px was synthesized by phosphorization of CoFe2O4 and applied in PMS activation for sulphachloropyridazine sodium (SCP) degradation. The SCP removal reached up to 94.2% in 30 min, with a reaction rate of 0.090 min−1. Particularly, CoFe2Px exhibited much lower cobalt ion leaching (0.082 mg L−1) than the reported cobalt-containing catalysts, due to the more intimate Co-Fe interaction and the surrounding of metals by phosphorus. Different from the free radical pathway in CoFe2O4/PMS system, a radical-nonradical coupling process was detected in CoFe2Px/PMS system, which was confirmed by quenching tests, electron paramagnetic resonance (EPR) measurements, and transformation intermediate analyses. Moreover, CoFe2Px demonstrates favorable durability for PMS activation and potential practicability for realistic wastewater treatment. This work provides new insights for rational design and mechanism exploration of transition-metal phosphides (TMPs) in the environmental catalysis field.

Mixed valence state cerium metal organic framework with prominent oxidase-mimicking activity for ascorbic acid detection: Mechanism and performance

It is indispensable to establish a simple, effective and accurate method for ascorbic acid (AA) detection since it plays a crucial role in human health. Herein, a novel oxidase mimic of mixed valence state cerium metal organic framework (MVCM) was successfully synthesized by in-situ partial oxidation of cerium metal organic framework (Ce-MOF). On account of the Ce (Ⅲ)/Ce (Ⅳ) redox couple inside, MVCM could directly catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to generate a blue color product (ox TMB) without adding H2O2, exhibiting a prominent intrinsic oxidase mimetic activity compared to Ce-MOF. Moreover, this catalytic mechanism of MVCM was further clarified by means of cyclic voltammetry (CV) test, UV–vis absorption spectra with O2 or N2 saturated condition and electron paramagnetic resonance (EPR) measurements. In the presence of AA, a redox reaction occurred between AA and ox TMB, and then resulting in a conspicuous blue color fading. By optimizing the testing conditions, a linear absorbance response was well correlated with the AA concentration ranging from 20 to 500 μM with a detection limit of 3.57 μM. MVCM also displayed the excellent selectivity and anti-interference performance for AA detection. Benefitting from the above, this AA detection method was applied in real Vitamin C effervescent tablets, showing a favorable reproducibility and feasibility. These results strongly indicated that the proposed method based on MVCM as an oxidase mimic might be a promising candidate for AA detection in food field.

Mechanistic insights into hydroxyl radical formation of Cu-doped ZnO/g-C3N4 composite photocatalysis for enhanced degradation of ciprofloxacin under visible light: Efficiency, kinetics, products identification and toxicity evaluation

In this study, a promising composite photocatalyst, Cu-doped ZnO coupled with g-C3N4 (Cu-ZnO/g-C3N4), was synthesized and applied for the enhanced degradation of a fluoroquinolone antibiotic ciprofloxacin (CIP) under visible light irradiation. The nearly complete removal of CIP could be achieved after 6 h, with a rate constant of 0.0105 min−1. As proved by various characterizations, the enhanced photocatalytic activity of Cu-ZnO/g-C3N4 was mainly attributed to the improvements of visible light absorption and electron–hole separation. Using the radical trappers, the electron spin resonance (ESR) and fluorescence measurements confirmed that a Z-scheme charge transfer route was exactly established at the heterojunction interface, thereby increasing the formation of hydroxyl radicals (•OH) from the hole-induced and electron-induced contributions simultaneously. Moreover, the kinetic effects of catalyst dosage, pollutant concentration and solution pH on CIP degradation were studied, and the intermediate products were identified by liquid chromatography–mass spectrometry (LC/MS) to propose the possible degradation pathways. The identified intermediates were basically presented with the decreased toxicities, indicating an effective control of ecological risks during the process. The above results verify the feasibility and applicability of visible light-driven Cu-ZnO/g-C3N4 photocatalysis for antibiotic wastewater treatment.

Defect-rich potassium amide: A new solid-state potassium ion electrolyte

One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes. KNH2, a new potassium-ion solid electrolyte has been developed in this study. Its ionic conductivity reaches 4.84 × 10−5 S cm−1 at 150 °C and can reach 3.56 × 10−4 S cm−1 after mechanochemical treatment. The result from electron paramagnetic resonance (EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH2 electrolyte. To the best of our knowledge, this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amide-based solid electrolyte for an all-solid-state potassium-ion battery.

Photoinduced release of odorous volatile organic compounds from aqueous pollutants: The role of reactive oxygen species in increasing risk during cross-media transformation

Photoinduced volatile organic compounds (VOCs) release from fatty alcohols at the air-water interface, has attracted considerable attention. This paper comprehensively explores the release of odorous VOCs from aqueous micropollutants under photoirradiation, especially in terms of the important role of the reactive oxygen species (ROS) in increased risk by cross-media transformation. The formation and distribution of photoinduced VOCs produced by aqueous benzyl alcohol (BzOH), a common ingredient in personal care products, were monitored in situ by online gas chromatography equipped with mass spectrometry and flame ionization detector (GC–MS/FID). The photoreaction of BzOH followed first-order kinetics with a rate constant of 0.0158/min under air. After 180 min of ultraviolet irradiation, the accumulated output of the gas-phase products benzene and benzaldehyde (BA) reached 3.8 μmol and 2.6 μmol respectively, being approximately 10 times that under nitrogen. According to electron paramagnetic resonance measurements, singlet oxygen mainly promoted the oxidation of BzOH to BA, which was an important intermediate producing benzene via photocleavage. Odorous alicyclic hydrocarbons were also generated through photorearrangement under nitrogen. On the other hand, the Henry's law constants of the main products were much lower than those of BzOH, indicating that the photoproducts would volatilize from the aqueous phase into the gas phase. The odor threshold of gas-phase products decreased to varying degrees after photoirradiation. Especially for BA, one of the main products, its odor threshold decreased 130 times compared with BzOH. This study shows that the risk of cross-media pollution could significantly increase due to the transformation of aqueous pollutants into odorous VOCs under photoirradiation and provides new insight into its risk prevention.

Kill three birds with one stone: Iron-doped graphitic biochar from biogas residues for ammonium persulfate activation to simultaneously degrade benzo[a]pyrene and improve lettuce growth

• The FBC-APS could simultaneously degrade BaP and improve plant growth in soil. • Biogas residues from food waste were converted into biochar and became useful resources. • Possible mechanisms for BaP degradation by FBC-APS have been proposed. A graphitized magnetic biochar material, Fe-impregnated biochar (FBC), was synthesized using biogas residue, a product of food waste after anaerobic fermentation. The FBC coupled with ammonium persulfate (APS) exhibited excellent performance in the catalytic degradation of benzo[a]pyrene (BaP), a pentacyclic polycyclic aromatic hydrocarbon (PAH). In the FBC-APS system, the pyrolysis temperature of biochar, the initial pH, and the FBC and APS dosages were all influencing factors for Bap degradation. The FBC at the pyrolysis temperature of 700 °C performed the best catalytic performance, and FBC-APS efficiently degraded BaP at a wide pH range of 3–11. Results from quenching experiments, electron spin resonance measurement, and electrochemical analysis were used as the basis to propose the possible degradation mechanisms of BaP by FBC-APS, including the radical and non-radical pathways. The radical-induced oxidation was attained by SO 4 ·− and O 2 ·− . The non-radical pathway involved two aspects, one contributed by 1 O 2 and the other achieved through electron transfer. Five BaP intermediates were tentatively determined. Finally, FBC-APS was applied to BaP-polluted soil, and the overall degradation rate reached 91.7% after 72 h. Lettuce growth experiment showed that FBC-APS enhanced soil nitrogen and potassium availability and lettuce growth. In summary, FBC-APS application to soil can degrade BaP, improve the manurial effect, and solve environmental problems brought by biogas residues, that is, killing three birds with one stone.

Design Considerations of a Dual Mode X-Band EPR Resonator for Rapid In-Situ Microwave Heating

This paper describes the design considerations for a dual mode X-band continuous wave (CW) Electron Paramagnetic Resonance (EPR) cavity, for simultaneous EPR measurement and microwave heating of the same sample. An elliptical cavity geometry is chosen to split the degeneracy of the TM110 mode, allowing for a well resolved EPR signal with the TM110,a and TM110,b modes resonating at around 10 GHz and 9.5 GHz, respectively, the latter of which is used for EPR measurements. This geometry has the benefit that the TM010 mode used for microwave heating resonates at 6.1 GHz, below the cut off frequency of the X-band waveguide used for the EPR channel, providing effective isolation between the heating and EPR channels. The use of a pair of 9 µm thick copper clad laminates as the flat cavity walls allows for sufficient penetration of the modulation field (Bmod) into the cavity, as well as maintaining a high cavity Q factor (> 5700) for sensitive EPR measurements. Locating the heating port at an angle of 135° to the EPR port provides additional space for easier coupling adjustment and for larger sample access to be accommodated. The associated decrease of EPR signal strength is fully compensated for by using a 7.2 GHz low pass filter on the heating port. EPR spectra using 1.6 mm and 4.0 mm sample tubes are shown at room temperature (298 K) and 318 K for a standard Cu(acac)2 solution, demonstrating the effectiveness of this dual-mode EPR cavity for microwave heating during EPR detection.

Constructing a 3D interconnected “trap-zap” β-CDPs/Fe-g-C3N4 catalyst for efficient sulfamethoxazole degradation via peroxymonosulfate activation: Performance, mechanism, intermediates and toxicity

A novel and high-efficiency catalyst Fe doped g-C3N4 (Fe-g-C3N4) composited with β-cyclodextrin polymers (β-CDPs) was synthesized for activating peroxymonosulfate (PMS). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that the catalyst was 3D interconnected porous structure. The degradation rate constant of sulfamethoxazole (SMX) in β-CDPs/Fe-g-C3N4+PMS system was estimated to be 0.132 min−1, which was 14.7 times and 2.2 times that of g-C3N4+PMS and Fe-g-C3N4+PMS system, respectively. In addition, the β-CDPs/Fe-g-C3N4 exhibited superior degradation performance in a wide pH range (3.0–9.0) and good selectivity in the presence of other inorganic anions and natural organics. Radical scavenging, electron paramagnetic resonance (EPR) and electrochemical measurements indicated that 1O2 and Fe(V)O were the main active species for SMX degradation in β-CDPs/Fe-g-C3N4+PMS system. Moreover, β-CDPs accelerated electron transfer between catalyst and PMS and promoted the generation of reactive oxygen species (ROS) during PMS activation. The loading of β-CDPs increased the yields of Fe(V)O and 1O2 in the system and limited the leaching of Fe3+. In addition, the possible degradation pathways of SMX were described based on the intermediates detected by liquid chromatography-mass spectrometry (LC-MS), and the toxicity of the intermediates was also evaluated. This work investigate the role of β-CDPs in PMS activation for the first time and develop a promising material with potential for water treatment.

Understanding the self-catalyzed decomplexation mechanism of Cu-EDTA in Ti3C2Tx MXene/peroxymonosulfate process

Self-catalyzed decomplexation of Cu-ethylene diamine tetraacetic acid complex (Cu-EDTA) and recovery of Cu without addition of extraneous transition metals were achieved in Ti3C2Tx MXene/peroxymonosulfate (Ti3C2Tx/PMS) process. Free radical quenching experiments and electron spin resonance (ESR) measurements demonstrated that both hydroxyl radical (HO•) and sulfate radical (SO4•-) contributed to the degradation of Cu-EDTA. Activation of PMS by Ti3C2Tx initiated Cu-EDTA decomplexation and released free Cu ions. Then, the formation of Ti-O-Cu bonds between Cu ions and Ti3C2Tx accelerated the electron transfer from Ti3C2Tx to Cu(Ⅱ) and triggered Cu(Ⅱ)/Cu(Ⅰ) cycle, which further enhanced PMS activation and led to the self-catalyzed decomplexation of Cu-EDTA. Simultaneous recovery of Cu was achieved due to the excellent absorption performance of negative charged Ti3C2Tx towards Cu ions. This study revealed the self-catalyzed decomplexation mechanism of Cu-EDTA in the Ti3C2Tx/PMS process and provided a feasible strategy for heavy metal complexes treatment.

Synergistic activation of peroxymonosulfate by MnO/Fe3C encapsulated in N-doped carbon nanosheets for the enhanced degradation of bisphenol A

Our work is mainly focused on the N-doped porous carbon nanosheets with metal or metal oxide catalysts embedded for the activation of peroxymonosulfate. MOF derived MnO/Fe3C encapsulated in N-doped carbon nanosheets (MnO/Fe3C@NC) with controlled structure have been synthesized and showed more excellent performance than traditional Fe/Mn-based catalyst as a PMS activator. Specifically, in this study, the magnetic MnO/Fe3C@NC-1 catalyst as peroxymonosulfate (PMS) activator was successfully fabricated by calcination of Mn and Fe-based bimetallic organic framework (MnFe-MOF-74), which was converted into mix-phased MnO and Fe3C. The system of PMS + MnO/Fe3C@NC-1 completely degraded 10 mg/L of bisphenol A (BPA) in less than 20 min. The MnO/Fe3C@NC-1 exhibited better activity in PMS activation than MnO@NC and Fe/Fe3C@NC, indicating that the synergistic effect between MnO and Fe3C could be beneficial to enhance the catalytic performance. The competitive radical quenching technique and electron paramagnetic resonance (EPR) measurements revealed that both SO4•− and •OH might be mainly generated. Various influential factors affecting catalytic performance were systematically investigated. The magnetic catalyst also manifested an excellent stable performance in heterogeneous BPA oxidation for several runs. We believe that this work will provide a new prospect for the synthesis of MOF-derived catalysts with high catalytic performance for PMS activation.

Optical selection rules of the magnetic excitation in the S=12 one-dimensional Ising-like antiferromagnet BaCo2V2O8

In this study, we clarify the selection rules of optical transitions from the ground state to the magnetic excited states in the quasi-one-dimensional quantum Ising-like antiferromagnet ${\mathrm{BaCo}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$ with spin $S=\frac{1}{2}$ using the high-field electron spin resonance measurement with illuminating polarized electromagnetic waves. We demonstrate that the unconventional magnetic excitation via the pair creation of quasipaticles at wave numbers ${q}_{z}$ = $\ensuremath{\pi}/2$ and $\ensuremath{\pi}$ in the field-induced quantum critical state can couple with both oscillating magnetic and electric fields. Our density matrix renormalization group calculations indicate that the observed selection rules can be explained by two- and four-fold periodical spin interactions, originating from the screw chain structure in ${\mathrm{BaCo}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$, in addition to the magnetoelectric coupling between spins and electric dipoles.

Extreme g-Tensor Anisotropy and Its Insensitivity to Structural Distortions in a Family of Linear Two-Coordinate Ni(I) Bis-N-heterocyclic Carbene Complexes.

We report a new series of homoleptic Ni(I) bis-N-heterocyclic carbene complexes with a range of torsion angles between the two ligands from 68° to 90°. Electron paramagnetic resonance measurements revealed a strongly anisotropic g-tensor in all complexes with a small variation in g∥ ∼ 5.7-5.9 and g⊥ ∼ 0.6. The energy of the first excited state identified by variable-field far-infrared magnetic spectroscopy and SOC-CASSCF/NEVPT2 calculations is in the range 270-650 cm-1. Magnetic relaxation measured by alternating current susceptibility up to 10 K is dominated by Raman and direct processes. Ab initio ligand-field analysis reveals that a torsion angle of <90° causes the splitting between doubly occupied dxz and dyz orbitals, which has little effect on the magnetic properties, while the temperature dependence of the magnetic relaxation appears to have no correlation with the torsion angle.

Coupling morphology control and surface I grafting for boosting the photocatalytic activity of Bi2O2[BO2(OH)] nanosheets

Photocatalytic performance of semiconductors is currently limited by low solar light utilization, rapid charge recombination and limited reactive sites. Reducing the thickness of layered photocatalysts can shorten the charge transport distance to inhibit their recombination and provide more reactive sites. Surface ionic grafting can broaden the light absorption range and promote the separation efficiency of carriers. In this work, the surface iodine ion modified Bi2O2[BO2(OH)] nanosheets are synthesized by combining the surfactant-assisted hydrothermal method and room-temperature KI solution treatment route. These nanosheets show increased photoabsorption in visible region, enlarged specific surface area and promoted charge separation. Compared with the pristine Bi2O2[BO2(OH)], the surface I- modified Bi2O2[BO2(OH)] nanosheets exhibit substantially strengthened photocatalytic performance for degradation of BPA, which increases beyond 25 times. The total organic carbon content (TOC) test reveals that the mineralization process of BPA. Electron spin resonance (ESR) measurements disclose the radicals that play dominant role in the photocatalytic process and confirm their increased yield over I- modified Bi2O2[BO2(OH)] nanosheets. In addition, BiOB-S-I2 also shows universality for degradation of a variety of high-concentration pollutants, including rhodamine B, methyl orange, methylene blue, phenol, 2,4-dichlorophenol and tetracycline hydrochloride. This study may provide a combined strategy for exploring high-performance photocatalysts via microstructure control and surface ionic decoration.

Photocatalytic co-production of hydrogen gas and N-benzylidenebenzylamine over high-quality 2D layered In4/3P2Se6 nanosheets.

The concurrent photocatalytic synthesis of hydrogen gas and high-valued chemicals over two-dimensional semiconductors is extremely attractive to alleviate global energy and environmental concerns through directly using sunlight. Herein, a novel layered In4/3P2Se6 nanosheet is synthesized by a space confined chemical vapor conversion method, and it acts as a dual-functional photocatalyst to deliver the co-production of hydrogen gas and N-benzylidenebenzylamine from water reduction and selective benzylamine oxidation. The simultaneous yield of hydrogen gas and N-benzylidenebenzylamine is 895 μmol g-1 and 681 μmol g-1, respectively, within 16-hour continuous reaction involving a small amount of water in acetonitrile solvent. Moreover, 97.4% N-benzylidenebenzylamine selectivity from benzylamine oxidation can be achieved with continuous 10 hour-reaction only in acetonitrile solvent under ambient conditions. Further in situ electron paramagnetic resonance measurements and reaction optimization tests reveal that the reaction mechanism strongly relies on the conditions over the In4/3P2Se6 nanosheet photocatalyst.