Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions.The bimetallic hydroxides,catalyzing the oxygen evolution reaction(OER),have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage.Herein,the complete reconstruction of ultrathin CoNi(OH)_(2) nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction(SRR),forming heterojunction Ag@CoNi(OH)_(2) for bifunctional hydrolysis.Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides.The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates,thereby weakening the barrier formed by OOH^*.Ag@CoNi(OH)_(2) required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm^(-2),with nearly 98.6% Faraday efficiency.Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction,this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition.

Chemical looping conversion of methane via Fe_(2)O_(3)-LaFeO_(3)calcined from LaFe-MOF precursor

The effective utilization of natural gas resources is a promising option for the implementation of the"dual carbon"strategy.However,the capture of carbon dioxide with relatively lower concentration after the combustion of natural gas is the crucial step.Fortunately,the lattice oxygen is used for chemical cycle conversion of methane to overcome the shortcomings mentioned above.A method was proposed to synthesize perovskite for methane cycle conversion using metal organic framework as a precursor.Morphology and pore structure of Fe_(2)O_(3)-LaFeO_(3)composite oxides were regulated by precursor synthesis conditions and calcination process.Moreover,the chemical looping conversion performance of methane was evaluated.The results showed that the pure phase precursor of La[Fe(CN)_(6)]·5H_(2)O was synthesized with the specific surface area of 23.91 m^(2)·g^(-1)under the crystallization of 10 h and the pH value of10.5.Fe_(2)O_(3)-LaFeO_(3)was obtained by controlled calcination of La[Fe(CN)_(6)]·5H_(2)O and Fe_(2)O_(3)with variable mass ratio.The selectivity of CO_(2)can reach more than 99%under the optimal parameters of methane chemical looping conversion:m(Fe_(2)O_(3)):m(LaFeO_(3))=2:1,the reaction temperature is 900℃,the lattice oxygen conversion is less than 40%.Fe_(2)O_(3)-LaFeO_(3)still has good phase and structure stability after five redox reaction and regeneration cycles.

Exploring the impact of Nafion modifier on electrocatalytic CO_(2) reduction over Cu catalyst

Nafion as a universal polymer ionomer was widely applied for nanocatalysts electrode preparation.However,the effect of Nafion on electrocatalytic performance was often overlooked,especially for CO_(2)electrolysis.Herein,the key roles of Nafion for CO_(2)RR were systematically studied on Cu nanoparticles(NPs)electrocatalyst.We found that Nafion modifier not only inhibit hydrogen evolution reaction(HER)by decreasing the accessibility of H_(2)O from electrolyte to Cu NPs,and increase the CO_(2)concentration at electrocatalyst interface for enhancing the CO_(2)mass transfer process,but also activate CO_(2)molecule by Lewis acid-base interaction between Nafion and CO_(2)to accelerate the formation of^(*)CO,which favor of C–C coupling for boosting C_(2)product generation.Owing to these features,the HER selectivity was suppressed from 40.6%to 16.8%on optimal Cu@Nafion electrode at-1.2 V versus reversible hydrogen electrode(RHE),and as high as 73.5%faradaic efficiencies(FEs)of C_(2)products were achieved at the same applied potential,which was 2.6 times higher than that on bare Cu electrode(~28.3%).In addition,Nafion also contributed to the long-term stability by hinder Cu NPs morphology reconstruction.Thus,this work provides insights into the impact of Nafion on electrocatalytic CO_(2)RR performance.

Progress on the application of graphene-based composites toward energetic materials:A review

Carbon material is an important additive in energetic materials.Graphene is a monolayer carbon material in which carbon atoms are arranged in two-dimensional honeycomb structure,who has special optical,electrical,and mechanical properties.Recently,the application of graphene-based composites in energetic materials has received extensive attention.This review mainly summarizes the applications of graphene and graphene-based nanomaterials in energetic materials.The effects of these materials on the thermal stability,sensitivity,mechanical property,ignition and combustion of energetic materials were discussed.Furthermore,the progress of functionalized modification of graphene has been summarized,including covalent bonding modification and doping modification.These studies show that graphenebased materials exhibit excellent performances and might emerge as promising candidate for energetic materials.

Effects of channel wall wettability on gas-liquid dynamics mass transfer under Taylor flow in a serpentine microchannel

The wall wettability of microchannels plays an important role in the gas-liquid mass transfer dynamics under Taylor flow.In this study,we regulated the contact angle of the wall surface through surface chemical grafting polymerization under controlled experimental conditions.The dynamic changes of CO_(2)bubbles flowing along the microchannel were captured by a high-speed video camera mounted on a stereo microscope,whilst a unit cell model was employed to theoretically investigate the gas-liquid mass transfer dynamics.We quantitatively characterized the effects of wall wettability,specifically the contact angle,on the formation mechanism of gas bubbles and mass transfer process experimentally.The results revealed that the gas bubble velocity,the overall volumetric liquid phase mass transfer coefficients(kLa),and the specific interfacial area(a)all increased with the increase of the contact angle.Conversely,gas bubble length and leakage flow decreased.Furthermore,we proposed a new modified model to predict the gas-liquid two-phase mass transfer performance,based on van Baten’s and Yao’s models.Our proposed model was observed to agree reasonably well with experimental observations.

Oxidation of Partially Hydrolyzed Polyacrylamide from Polymer Flooding Processes Using Fenton Reagents

The degradation of partially hydrolyzed polyacrylamide(HPAM) found in alkaline/surfactant/polymer flooding sewage was investigated using Fenton-type reagents. Different Fenton reagent treatments for HPAM degradation were compared. The effects of pH, hydrogen peroxide(H_(2)O_(2)), ferrous ion(Fe^(2+)), and tartaric ion(C_(4)H_(4)O_(6)^(2-)) concentrations were studied. The degradation reaction occurred within a wide range of pH(3–9). The HPAM degradation performance of photo-Fenton processes using solar light and UV were compared with that of the Fenton process. The degradation rate was found to be strongly dependent on the H_(2)O_(2)/Fe^(2+)/C_(4)H_(4)O_(6)^(2-)molar ratio. The HPAM degradation efficiency was 90%, and the chemical oxygen demand removal efficiency was 85%. HPAM could be degraded into a compound with a lower molecular weight, but it was difficult to achieve complete mineralization to CO_(2). The presence of intermediate products hindered further oxidation in the Fenton process.

A novel synthesis of highly active and highly stable non-noble-nickel-modified persulfated Al_(2)O_(3)@ZrO_(2) core-shell catalysts for n-pentane isomerization

The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)have been successfully prepared and investigated for n-pentane isomerization.The results showed that the core-shell Ni-SA@Z-30 provided a sustained high isopentane yield(63.1%)with little or no deactivation within 5000 min at a mild reaction pressure of 2.0 MPa,which can be attributed to the following factors:(i)carbon deposition was greatly suppressed by the large pore size and huge pore volume;(ii)the loss of sulfur entities was suppressed because the small and highly dispersed tetragonal ZrO_(2) particles can bond with the S species strongly;(iii)strong Brønsted acidity can be maintained well after the isomerization.The pore structures and acid nature of the core-shell Ni-SA@Z-x are entirely different from those of the normal structure Ni-S_(2)O_(8)^(2−)/ZrO_(2)-Al_(2)O_(3),even though the Al content and the compositions of the individual components are the same.The Al_(2)O_(3)cores endow the catalysts with high internal surface area and high mechanical strength.Meanwhile,the ZrO_(2) shell,which consists of more and smaller tetragonal ZrO_(2) particles because of the large surface area of the Al_(2)O_(3)core,promotes the formation of more stable sulfur species and stronger binding sites.

Effect of nanocomposite pour point depressant EVAL/CNT on flow properties of waxy crude oil

The nanocomposite EVAL-CNT was produced by chemical grafting in the solution system through the esterification of ethylene-vinyl alcohol copolymer (EVAL) and carboxylated multi-walled carbon nanotubes (O-MWCNT), and its structural properties were characterized. The improvement of the rheological properties of the waxy oil system by the novel pour point depressant was investigated using macroscopic rheological measurements and microscopic observations. The results showed that EVAL-CNT nanocomposite pour point depressant (PPD) could significantly reduce the pour point and improve the low temperature fluidity of crude oil and had better performance than EVAL-GO at the same addition level. The best effect was achieved at the dosing concentration of 400 ppm, which reduced the pour point by 13 ℃ and the low-temperature viscosity by 85.4%. The nanocomposites dispersed in the oil phase influenced the precipitation and crystallization of wax molecules through heterogeneous crystallization templates, which led to the increase of wax crystal size and compact structure and changed the wax crystal morphology, which had a better effect on the rheological properties of waxy oil.

Encapsulation of ionic liquid, phosphotungstic acid inside the nanocages of MIL-101(Cr): Effective and reusable catalyst for efficient solvent-free oxidative desulfurization from fuel oil

Oxidative desulfurization from fuel oil is one of the important methods for deep desulfurization.The development of efficient oxidative desulfurization catalysts is crucial for improving the desulfurization performance.Successful encapsulation of phosphotungstic acid(HPW)and ionic liquid(BMImBr)inside the mesoporous cages of MIL-101(Cr)was accomplished through a combination of“bottle around ship”and“ship in bottle”methods.The obtained BMImPW@MIL-101(Cr)composite was characterized by XRD,FTIR,BET,SEM,XPS and ICP methods.Results indicated that the BMImPW@MIL-101(Cr)composites with PW^(3−) loading of 23.1–50.7 wt%were obtained,demonstrating that the“bottle around ship”method is beneficial to make full use of nanocages of MIL-101(Cr)to obtain expected high loading of active PW^(3−) .The BMImPW@MIL-101(Cr)exhibits excellent reusability with no evidence of leaching of active PW^(3−) and BMIm^(+),and well-preserved structure after successive cycles of regeneration and reuse.The significantly improved stability of BMImPW@MIL-101(Cr)as compared to HPW@MIL-101(Cr)is possibly because the leaching of the active PW^(3−) −sites can be greatly suppressed by forming large size of BMImPW owing to introduction of BMIm^(+)cation.The BMImPW@MIL-101(Cr)exhibited excellent catalytic activity for solvent free oxidative desulfurization of refractory sulfides.The enhanced oxidative desulfurization activity as compared to HPW@MIL-101(Cr)can be explained by the intimate contact of sulfides with active PW^(3−) sites owing the strong attraction of BMIm^(+)cation with the sulfides.

Coupling Agent Grafting Assisted Synthesis of C3N4-ZrO_(2) Heterojunction Composites with Enhanced Photocatalytic Performance

Heterojunction composites were prepared by silane coupling agent grafting from synthesized graphitic carbon nitride(g-C_(3)N_(4))and commercially available zirconia(ZrO_(2)).The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,UV-vis diffuse reflectance spectroscopy(DRS),photoluminescence(PL)spectroscopy,and electrochemical impedance spectroscopy(EIS).The photocatalytic activity of the composites was evaluated by the degradation of methylene blue(MB)under visible light irradiation.The results showed that heterojunction composites of g-C_(3)N_(4) and ZrO_(2) could be successfully prepared by coupling agent grafting.The optimal mass ratio of g-C_(3)N_(4) and ZrO_(2) was 2:1,with an activity that was 3.8 times higher than g-C_(3)N_(4) and 15.3 times higher than ZrO_(2).This was ascribed to the stronger light absorption,faster interfacial charge transfer,and lower photogenerated carrier recombination of the heterojunction composites.

Mechanism of Capacity Fading Caused by Mn(Ⅱ)Deposition on Anodes for Spinel Lithium Manganese Oxide Cell

The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application.The traditional opinion is that Mn（Ⅱ） ions in the anode are reduced to the metallic manganese that helps for catalyzing electrolyte decomposition.This could poison and damage the solid electrolyte interface（SEI） film,leading to the the capacity fade in Li-ion batteries.We propose a new mechanism that Mn（Ⅱ） deposites at the anode hinders and/or blocks the intercalation/de-intercalation of lithium ions,which leads to the capacity fade in Li-ion batteries.Based on the new mechanism assumption,a kind of new structure with core-shell characteristic is designed to inhabit manganese ion dissolution,thus improving electrochemical cycle performance of the cell.By the way,this mechanism hypothesis is also supported by the results of these experiments.The LiMn2-xTixO4 shell layer enhances cathode resistance to corrosion attack and effectively suppresses dissolution of Mn,then improves battery cycle performance with LiMn_2O_4 cathode,even at high rate and elevated temperature.

Production of aryl oxygen-containing compounds from catalytic pyrolysis of bagasse lignin over LaTixFe1xO3

A new approach,named production of aryl oxygen-containing compounds from the catalytic pyrolysis of bagasse lignin(BL) over perovskite oxide,was proposed,A series of LaTixFe1-xO3(LTF-x) samples were prepared by the solid state reaction method.The crystal phase and morphology of LTF-x were characterized by XRD and SEM respectively.Catalytic pyrolysis performance of LTF-x was performed by TG-DTG and the distribution patterns of gaseous,liquid and solid products from BL was investigated using a fixed-bed micro-reactor.The optimal reaction conditions were determined:the pyrolysis temperature was 600℃,the mass ratio of mBL:mLTF-0.2 was 3:1,the veloeity of earrier gas was 100 ml·min-1.The gaseous produets were mainly eomposed of CO2,CO,CH4 and CnHm(n=2-4,m=2 n+2 or m=2 n),The main aryl oxygen-containing compounds in liquid products were phenolics,guaiacols,syringols and phenylates,the rest were benzenes,furans,esters and carboxylic acid.The total contents of aryl oxygencontaining compounds were from 62% up to more than 72% under the action of the perovskite.Moreover,the LTF-0.2 sample had nice regenerability.

Enhanced photocatalytic NO removal and toxic NO2 production inhibition over ZIF‐8‐derived ZnO nanoparticles with controllable amount of oxygen vacancies

The controlled introduction of oxygen vacancies(OVs)in photocatalysts has been demonstrated to be an efficient approach for improving the separation of photogenerated charge carriers,and thus,for enhancing the photocatalytic performance of photocatalysts.In this study,a two‐step calcination method where ZIF‐8 was used as the precursor was explored for the synthesis of ZIF‐8‐derived ZnO nanoparticles with gradient distribution of OVs.Electron paramagnetic resonance measurements indicated that the concentration of OVs in the samples depended on the temperature treatment process.Ultraviolet–visible spectra supported that the two‐step calcined samples presented excellent light‐harvesting ability in the ultraviolet‐to‐visible light range.Moreover,it was determined that the two‐step calcined samples presented superior photocatalytic performance for the removal of NO,and inhibited the generation of NO2.These properties could be attributed to the contribution of the OVs present in the two‐step calcined samples to their photocatalytic performance.The electrons confined by the OVs could be transferred to O2 to generate superoxide radicals,which could oxidize NO to the final product,nitrate.In particular,the NO removal efficiency of Z 350‐400(which was a sample first calcined at 350℃ for 2 h,then at 400℃ for 1 h)was 1.5 and 4.6 times higher than that of Z 400(which was one‐step directly calcined at 400℃)and commercial ZnO,respectively.These findings suggested that OV‐containing metal oxides that derived from metal‐organic framework materials hold great promise as highly efficient photocatalysts for the removal of NO.

Enhancing an internal electric field by a solid solution strategy for steering bulk-charge flow and boosting photocatalytic activity of Bi_(24)O_(31)Cl_(x)Br_(10-x)

Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community;however,a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear.Herein,a series of Bi_(24)O_(31)Cl_(x)Br_(10-x) solid solutions with the same structural characteristics were synthesized by crystal structure regulation.Combining density functional theory calculation,Kelvin probe force microscopy,and zeta potential testing results,an enhanced internal electric field(IEF)intensity between[Bi_(24)O_(31)]and[X]layers was achieved by changing halogen types and ratios.This greatly facilitated bulk-charge separation and transfer efficiency,which is significant for the degradation of phenolic organic pollutants.Owing to the enhanced IEF intensity,the charge carrier density of Bi_(24)O_(31)Cl_(4)Br_(6) was 33.1 and 4.7 times stronger than that of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Therefore,Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A,which was 6.21 and 2.71 times higher than those of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Thus,this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.

An Efficient Extraction-Free Method for Oxidative Desulfurization of Model Fuels Employing Cross-Linked Polyionic Liquid Phosphotungstate Catalysts

An efficient extraction-free oxidative desulfurization(ODS)process using a series of cross-linked polyionic liquid phosphotungstate(CLPIL-PW)catalysts is reported.The cross-linked PILs were prepared with DVB and 1-n-alkyl-3-vinyl imidazole hydrobromide(alkyl=ethyl,butyl,octyl,dodecyl),and were then assembled with phosphotungstic acid(H_(3)PW_(12)O_(40))to form the catalysts.The CLPIL-PWs have been applied to the oxidative removal of dibenzothiophene(DBT)from model oil with H_(2)O_(2) as an oxidant.The effects of ionic liquid(IL)cationic species,varying the DVB/IL molar ratio in the polymerization process,and varying operating conditions were investigated.The CLPIL-PWs were characterized by inductively coupled plasma(ICP)mass spectrometry,elemental analysis,scanning electron microscopy(SEM),Fourier transform infra-red(FTIR)spectroscopy,X-ray diffraction(XRD),^(13)C and^(31)P nuclear magnetic resonance(NMR)spectroscopy.The polydivinylbenzene-co-1-n-octyl-3-vinyl imidazole phosphotungstate(P(DVB-OVIm)PW)exhibited the highest DBT removal efficiency(99.9%)and remarkable recyclability,and could be reused eight times without reducing its activity.Finally,an extraction-free ODS mechanism is proposed.

Fabrication of Fe Nanoparticles into N-doped Mesoporous Carbon Nanotube Derived from Rice-Like Fe/N-MOF and Its ORR Catalytic Performance for MFC

The development of non-noble metal oxidation reduction catalysts(ORR)to improve microbial fuel cell(MFC)performance remains extremely challenging.Herein,the nitrogen-doped iron-based porous carbon nanotube Fe/N@MC-T ORR catalysts were derived from Fe/N-MOF by pyrolyzation using acetonitrile as the nitrogen precursor in a low-cost organic solvent.The Fe/N@MC-T catalysts under different pyrolysis temperatures were characterized by SEM,TEM,BET,XRD,and XPS techniques.Fe/N-MOF showed a smooth rice-like structure with a particle size of about 400×50 nm^(2).The Fe species in Fe/N@MC-T mainly exists in the form of zero-valent iron with a small amount of Fe3C.The results of electrochemical tests revealed that the onset and half-wave potentials of Fe/N@MC-700 were 0.89 V and 0.80 V,respectively,which were only slightly lower than those of the commercial Pt/C(0.92 V and 0.82 V).The MFC with Fe/N@MC-700 showed a highest power density of 864.1 mW/m^(2),which was about 2.25 times that of MFC with carbon cloth,and was slightly lower than that of MFC with Pt/C(20%)(1002.0 mW/m^(2)),which demonstrated that the Fe particles wrapped in carbon nanotubes possessed a relatively high ORR activity.

Synthesis, Crystal Structure and Thermal Stability of the Coordination Polymer [Co(2-mpac)_2(py)·4H_2O)]_n

A new coordination polymer with the formula of [Co（2-mpac）2（py）·4H2O）]n （1, 2-mpac = 5-methyl-2-pyrazinecarboxylic acid, py = pyrazine） has been synthesized through hydrothermal synthesis and structurally characterized by X-ray single-crystal diffraction method. 1 exhibits a 3D supramolecular network. Crystal data： monoclinic, space group C2/m, a = 15.907（9）, b = 7.104（3）, c = 9.793（5）, β = 95.232（8）o, V = 1102.0（10）3, Z = 2, S = 0.995, the final R = 0.0509, wR = 0.1626 for 1002 observed reflections with （I 〉 2σ（I）） and R = 0.0530, wR = 0.1667 for all data. In addition, elemental analysis, IR and thermalgravimetric analysis are presented.

A New Solvent-free Synthesis of a, a'-Dibenzylidenecycloalkanones from Acetals with Cycloalkanones under Microwave Irradiation

A new rapid synthetic method is described for synthesis of a, a-dibenzylidene- cycloalkanones by the reaction of acetals and cycloalkanones without solvent using BF3稥t2O as catalyst under microwave irradiation.

Degradation of Chloroanilines in Aqueous Solution by Contact Glow Discharge Electrolysis

Contact glow discharge electrolysis of some chloroanilines in sodium sulfate was investigated in different initial concentrations. Each of them underwent the dechlorination, deam-ination through oxidative degradation, and were eventually decomposed into hydrogen carbonate and carbon dioxide. It was testified that the chlorine atom and amidogen could be transformed into chloride ion and nitrite ion, respectively. Fe2+ has a remarkable catalytic effect on the degradation of them. On the basis of the detailed analysis of the intermediate products and kinetic behaviors, the reaction pathway was proposed, in which the attack of hydroxyl radical on the benzene ring of starting material might be a key step.

Cobalt(I) Catalyzed Reaction of Benzaldehydes with Functionalized Benzylic Zinc Halides

Functionalized benzylic zinc halides reacted with benzaldehydes in the presence of Lewis acid Me3SiCl giving high yields of trans-stilbenes under the catalysis of Co(PPh3)3Cl.