Mo–Ru–W chalcogenide electrodes prepared by chemical synthesis and screen printing for fuel cell applications

We report the results obtained in the characterization of binary W–Se, Ru–Se as well as ternary W–Ru–Se and Mo–Ru–Se electrocatalysts prepared by screen printing and chemical synthesis. The results indicate that Mo–Ru–Se based catalysts prepared by chemical synthesis possess good electrocatalytic activity for oxygen reduction. The final composition of the compound depends on the starting weight percentage of the carbonyl compounds and the post-preparation processing. As-prepared, Mo–Ru–Se was found to be stable in acid medium (H₂SO₄) with high catalytic activity, but after heat treatment the catalytic activity reduced appreciably due to the loss of Se from the compound.     

Potentials of bio-hydrogen and bio-methane production from diseased swines

Diseased swines can be utilized as substrate for anaerobic fermentation after proper pretreatment. The cumulative bio-hydrogen and bio-methane production yields were taken as targets, the effects of different initial pH values and enzyme concentration on bio-hydrogen and bio-methane production characteristics by anaerobic fermentation from diseased swines were investigated. Results showed that the highest cumulative hydrogen yield reached up to 175.84 mL/L when pH value and enzyme concentration are of 8.0 and 2.5% respectively. While the maximum cumulative bio-methane-production yield of 104.59 mL/L was obtained when the enzyme concentration and pH value are of 1.0% and 8.0 respectively. The effects of enzyme on cumulative bio-hydrogen yield was greater than that of the initial pH while it is opposite for cumulative bio-methane yield. The potential of bio-hydrogen production from diseased swines is higher than that of bio-methane production.     

Enhanced low temperature catalytic activity of Ni/Al–Ce0.8Zr0.2O2 for hydrogen production from ammonia decomposition

Ammonia decomposition is an effective way for high purity hydrogen production, yet the increase of catalytic activity at low temperatures remains a big challenge for this process. In this paper, a CeO₂–ZrO₂ composite with Al as the secondary dopant was synthesized by the co-precipitation method, which was used as the carrier of nickel metal for ammonia decomposition. The experimental results showed that an obvious increase in catalytic activity of the ammonia decomposition at the relatively low temperature range of 450–550 °C was achieved over the nickel catalyst with CeO₂–ZrO₂ composite as the metal carrier. Specifically, the complete decomposition of ammonia was achieved at 580 °C for Ni/Al–Ce_0.8Zr_0.2O₂ catalyst, while only 92% of ammonia was decomposed at 600 °C over the reference Ni/Al₂O₃ catalyst. The characterization results indicated that the introduction of Al as the secondary dopant of ceria not only increases the specific surface area and oxygen defects on the surface, but also enhances the nickel metal dispersion and metal-support interaction, thus enhances the catalytic performance of Ni/Al–Ce_0.8Zr_0.2O₂ catalyst in the ammonia decomposition.     

Vanadium (V) and Niobium (Nb) as the most promising co-catalysts for hydrogen sulfide splitting screened out from 3d and 4d transition metal single atoms

The options of transition metals as co-catalysts for photocatalytic H₂S splitting are restricted to some noble metals and related compounds which have noticeable achievements despite their high prices. Substituting with cheap transition metals and downsizing the size to single atom level are economic ways to lower the cost. Herein, the s-triazine graphite-like carbon nitride sheet g-C₃N₄ (001) is chosen as the model to study the performances of 3d and 4d transition metal single atoms (TMSA = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) in H₂S splitting based on density functional theory (DFT) calculations. It is found that low-cost transition metals with industrial relevance (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Cd) are completely comparable with noble metals (Ru, Rh, Pd, Ag). Among them, V and Nb are the most promising co-catalysts with good thermodynamic stabilities, favorable responses to visible light, high photoinduced electron-hole separation efficiencies, sufficient potentials for H₂S splitting, and low energy barriers for H₂S dissociation into H₂ and S. The noticeable improved activities of V/g-C₃N₄ and Nb/g-C₃N₄ are attributed to the formation of strong interfacial chemical bonds which could promote electrons transferring to H₂S derivates. In addition, the introduction of photoinduced electrons could further improve the activities of V/g-C₃N₄ and Nb/g-C₃N₄ with more electrons transferring to H₂S derivates. It is expected that this work could provide a helpful guidance to choose appropriate TMSA co-catalysts as references for H₂S splitting.     

Molten salt synthesis of Z-scheme CeO2/C3N4 photocatalysts with excellent properties for removal of organic pollutants: Characterization,kinetics and mechanisms

In this work,we firstly synthesized a CeO₂/C₃N₄ photocatalyst with Z-scheme heterojunction by a facile LiC-KCI molten salt method.The synthesized catalyst has an excellent quality for removing organic pollution of dyes and antibiotics in wastewater.As an example,the CeCN-1:5 prepared with a mass ratio of Ce₂(CO₃)₃·xH₂O:C₃H₃N₆=1:5 exhibits a methylene blue(MB) removal capacity of 100%with...     

New luminescent 10-oxybenzoquinolate complexes of rare earth metals

A series of Sc,Y,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Ho,Er,Tm and Yb complexes with oxybenzoquinoline ligands(BQ) was synthesized by the reactions of 10-hydroxybenzo[h]quinoline with cyclopentadienides or tris(trimethylsilyl)amides of rare earth metals.The structure,as well as the photo-and electroluminescent(PL,EL) properties of these complexes in solutions and solid state were studied.In solutions,complexes of sodium and lanthanides exhibit double peaked ligand-centered PL of enol and keto forms of BQ with a...     

Ultra-high sensitivity of rhodamine B sensing based on NaGdF4:Yb3+,Er3+@NaGdF4 core-shell upconversion nanoparticles

A series of mono-dispersed hexagon NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 core-shell nanoparticles with different shell thickness were synthesized via a co-precipitation method. Nanoparticles with high upconversion fluorescent emissions result in large signal-to-noise ratio, which guarantees the accuracy of the sensitivity. Besides, the maximum sensitivity of these NPs as detection film increases first and then decreases with the shell thickness increasing. When the shell thickness is 2.3 nm(NaGdF_4-2), the maximum sensitivity(0.69959 ppm~(-1)) is reached. A large degree of overlap between the rhodamine B absorption band and the Er~(3+) green emission bands ensures that the NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 nanoparticles can be used as fluorescent probe to detect the concentration of rhodamine B based on fluorescent intensity ratio technology. The linear relationship between the rhodamine B concentration and the intensity ratio(R) of green and red emission intensity(I_(S+H) and I_F) were studied systematically. The result shows that the maximum sensitivity can be obtained in low concentration rhodamine B(4 ppm), which is lower than the reported minimum detection concentration. Thus, the ultra-high sensitivity detection by NaGdF_4:Yb~(3+),Er~(3+)@NaGdF_4 core-shell upconversion nanoparticles in low concentration can be realized,which provides promising applications in bio-detection filed.     

The inter-electrode capacitance of wedge and strip position sensing elements

A method of calculating the inter-electrode capacitances of wedge and strip position sensing elements is presented. Estimates made using the method are compared to measured values and found to be in resonable agreement. Ank alternative formula is shown to be semiempirical, requiring calibration with similar, already manufactured, wedge and strips before it can be used.