Huimin Yang

A novel photoelectrocatalytic approach for water splitting by an I-BiOCl/bipolar membrane sandwich structure

A novel photoelectrocatalytic approach for water splitting through an I-BiOCl/bipolar membrane sandwich structure with photoelectro-synergistic catalysis is proposed in this study. The I-BiOCl/bipolar membrane sandwich structure could facilitate separation of photoexcited electrons and holes, thereby promoting the splitting of water, increasing the efficiency of H2 generation and saving energy consumption.

Performance of sodium bromate as cathodic electron acceptor in microbial fuel cell

The potential of using sodium bromate as a cathodic electron acceptor in a microbial fuel cell (MFC) was determined in this study. The effects of sodium bromate concentration and initial catholyte pH on the electricity production of the MFC were investigated. The MFC performance improved with increasing sodium bromate concentration and decreasing catholyte pH. The maximum voltage output (0.538 V), power density (1.4908 W m(-3)), optimal open circuit potential (1.635 V), coulombic efficiency (11.1%), exchange current density (0.538 A m(-3)) and charge transfer resistance (4274.1 Ω) were obtained at pH 3.0 and 100 mM sodium bromate. This work is the first to confirm that sodium bromate could be used as an electron acceptor in MFCs.

Nanoindentation characterised plastic deformation of a Al0.5CoCrFeNi high entropy alloy

Abstract The plastic deformation of a high entropy alloy Al0.5CoCrFeNi was investigated by instrumented nanoindentation over a broad range of strain rates at room temperature. Results show that the creep behaviour depends on the strain rate remarkably. In situ scanning images showed a significant pile up around the indents, demonstrating that a highly localised plastic deformation occurred in the process of nanoindentation. Under different strain rates, contact stiffness and elastic modulus basically remain unchanged. However, the hardness decreases as indentation depth increases due to indentation size effect. For the same maximum load, serrations became less prominent as the loading rate of indentation increased. Similar serrations have been observed in the current alloy upon quasi-static compression.

In situ electrochemical synthesis of MOF-5 and its application in improving photocatalytic activity of BiOBr

Abstract Metal–organic frameworks (MOFs) are important functional materials. MOF-5 (IL) (Zn 4 O(BDC) 3 (BDC=1,4-benzene- dicarboxylate) was in situ synthesized by the electrochemical method using a tunable ionic liquid (IL), 1-butyl-3-methylimidazolium chloride, as template. The crystallization of distinctly spherical MOF-5 (IL) synthsized in ionic liquid by the electrochemical method is attributed to π–π stacking effect, ionic bond, and coordination bond. The analysis results show that the product MOF-5(IL) exhibits better crystallinity and higher thermal stability than MOF-5 generated using the solvothermal method. The cyclic voltammetry reveals that the electrosynthesis reaction is irreversible and controlled by the diffusion. The experiments on methylorange degradation show that the unique structure characteristics of MOF-5(IL) can enhance the photocatalytic ability of BiOBr. Therefore, MOFs can replace noble metals to improve the photocatalytic properties of bismuth oxyhalide.

Superior Mechanical Properties of AlCoCrFeNiTi x High-Entropy Alloys upon Dynamic Loading

High-entropy alloys with composition of AlCoCrFeNiTix (x: molar ratio; x = 0, 0.2, 0.4) under quasi-static and dynamic compression exhibit excellent mechanical properties. A positive strain-rate sensitivity of yield strength and the strong work-hardening behavior during plastic flows dominate upon dynamic loading in the present alloy system. The constitutive relationships are extracted to model flow behaviors by employing the Johnson-Cook constitutive model. Upon dynamic loading, the ultimate strength and fracture strain of AlCoCrFeNiTix alloys are superior to most of bulk metallic glasses and in situ metallic glass matrix composites.

A photocatalytic graphene quantum dots–Cu2O/bipolar membrane as a separator for water splitting

Graphene quantum dots–Cu2O (GQDs–Cu2O) is introduced to a bipolar membrane (BPM) interlayer and shown to be a novel, efficient water dissociation catalyst. This paper reports the use of the GQDs–Cu2O/BPM composite as a separator to prevent the crossover of hydrogen and oxygen. Under reverse bias and sunlight irradiation conditions, GQDs–Cu2O/BPM exhibits lower membrane resistance than BPM. GQDs–Cu2O/BPM also minimizes pH gradient formation, resulting in a decreased potential loss with respect to that of BPM. The efficiency of GQDs–Cu2O/BPM as a diaphragm in H2 generation and energy conservation was assessed. GQDs–Cu2O/BPM was found to be 88.6% and 14.5% more efficient than BPM in H2 generation at the current density of 90 mA cm−2 and under sunlight irradiation, respectively. The composite also saved about 22.6% energy with respect to that of BPM at 90 mA cm−2.

Enhanced photoelectric performance of (2Al, S) co-doped rutile SnO2

In this study, theoretical calculations and experiments have been carried out to investigate the photoelectric performance of (2Al, S) co-doped rutile SnO2. The electronic structures are studied by density functional theory (DFT). It is found that the metal Al can assist the bonding of the incorporated S with the neighboring O in SnO2, introducing new energy levels in the forbidden band of SnO2, which enhance the photoelectric performance. Meanwhile, the experiments are conducted to verify this. The (2Al, S) co-doped SnO2 with different doping ratios are prepared by a hydrothermal method. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results show that all the samples have rutile structure without any extra phase, and the dopant S2− ion was implanted into the crystalline lattice of (2Al, S) co-doped SnO2 and Al dopants replaced Sn atoms. The photoelectric performance tests show Al and S co-doping can improve the photoelectric performance, especially with a doping ratio of 5%, when the photocurrent reaches maximum of 3.0 μA cm−2 which is almost twice as much as pure SnO2, and the impedance is the smallest. The experiments results are consistent with our theoretical calculations. These findings are expected to be helpful for the design of highly active tin oxide-based photoelectric materials.

A BiOCl/bipolar membrane as a separator for regenerating NaOH in water-splitting cells

Photoconductive BiOCl has been introduced into a bipolar membrane (BPM) interlayer to prepare a BiOCl/BPM. This paper reports the use of the BiOCl/BPM composite to regenerate NaOH. Under reverse bias and sunlight irradiation conditions, the BiOCl/BPM resistance and cell voltage can be significantly decreased due to the photoconductivity of the BiOCl photocatalyst, which lead to the energy consumption decline in regenerating NaOH. Moreover, the electric field in the interlayer of the BiOCl/BPM contributes in separating the photo-generated electron–hole pairs of the BiOCl photocatalyst, thereby increasing the current efficiency of regenerating NaOH.

Dynamic Deformation Behaviors of an In Situ Ti-Based Metallic Glass Matrix Composite

Quasi-static and dynamic deformation behaviors, fracture characteristics, and microstructural evolution of an in situ dendrite-reinforced metallic glass matrix composite: Ti50Zr20V10Cu5Be15 within a wide range of strain rates are investigated. Compared with the quasi-static compression, the yielding stress increases, but the macroscopic plasticity significantly decreases upon dynamic compression. The effects of the strain rate on strain hardening upon quasi-static loading and flow stress upon dynamic loading are evaluated, respectively. The Zerilli-Armstrong (Z-A) model based on dendrite-dominated mechanism is employed to further uncover the dependence of the yielding stress on the strain rate.

Evolution of hardness and modulus within a cold-rolled in situ dendrite-reinforced metallic glass matrix composites

Abstract Cold-rolled in situ dendrite/metallic glass matrix (MGM) composites with a composition of Ti48Zr18V12Cu5Be17 exhibit a fact that modulus and hardness of matrix is decreased with the increasing in thickness reduction, while the modulus of dendrites remains constant, and hardness tends to increase sharply with the increase in thickness reduction < 30% and then it approximately remains constant. Free volumes created by plastic deformation lead to the decrease of the matrix modulus. Dendrites are restricted by surrounding matrix, which results in the modulus of dendrites constant. Multiplication of shear bands is the dominant mechanism affecting the hardness of the matrix. The present study gives a guideline to predict the evolution of hardness and modulus in both dendrites and glass matrix in such dual-phase composites.