Oxygen reduction reaction on (Pt–NbPO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)/MWCNTs electrodes prepared by microwave irradiation method

(Pt–NbPO _x )/multi-walled carbon nanotubes (MWCNTs) with different NbPO _x MWCNTs were prepared by a simple microwave irradiation method. The (Pt–NbPO _x )/MWCNTs catalyst was characterized, and the kinetics toward oxygen reduction reaction (ORR) was determined, compared with that of Pt/MWCNTs catalyst. It was found that 10 wt% NbPO _x was the best loading in terms of current density. The number of exchange electrons for the ORR was found to be close to four on both (Pt–NbPO _x )/MWCNTs and Pt/MWCNTs.     

直接甲醇燃料电池电催化剂性能衰减研究

通过单电池放电试验, 考察了直接甲醇燃料电池(DMFC)电催化剂的性能衰减情况. 透射电镜(TEM)和X射线衍射分析(XRD)结果表明, 放电试验后阳极电催化剂的粒径变化很小, 而阴极电催化剂的粒径则显著增大. DMFC内部的液相环境是促使Pt粒子聚结的主要原因. 阳极催化剂中Ru的存在抑制了Pt粒子的生长. 阳极和阴极电催化剂的电化学表面积(ECSA)在放电后都有所降低, 且下降幅度均高于比表面积(SSA)的下降幅度. 放电过程中阳极电催化剂发生了Ru的流失.     

A novel ball-in-ball hollow oxygen-incorporating cobalt sulfide spheres as high-efficient electrocatalyst for oxygen evolution reaction

Transition-metal chalcogenides with hollow nanostructure,especially cobalt sulfides,are considered as the most pro mising non-precious metal catalysts for oxygen evolution reactio n.However,it is difficult to synthesize oxygen-containing cobalt sulphides with hollow structure due to the different physical/chemical properties between metal sulfides and metal cobalts.Herein,we report a novel oxygencontaining amorphous cobalt sulfide ball-in-ball hollow sphere s(Co-S-O BBHS) synthesized by an anion exchange method.Taking advantage of the ball-in-ball hollow structure,the amorphous Co-S-O BBHS shows supe rior oxygen evolution reaction(OER) electrocatalytic performance with a low overpotentiat of285 mV at 10 mA/cm~2,small Tafel slope of 49.67 mV/dec,high Faraday efficiency of 96%,and satisfied durability.Experiments and DFT calculations demonstrate that the introduction of oxygen and sulfur modulates the electronic structure of Co-S-O BBHS,thus enhancing the adsorption of *0(adsorbed 0 species on catalyst surface) intermediate,which greatly boosts the catalytic activity towards OER.This work provides a new strategy for controllable synthe sis of complex hollow structures of transition-metal chalcogenides for OER.     

碳载PdPb催化剂的制备及对甲酸氧化的电催化性能

采用液相还原共沉积法制备出高活性纳米电催化剂PdPb/C, 研究发现, 碳载Pd催化剂中加入Pb能够提高催化剂对甲酸的电氧化活性, 并改变甲酸氧化的反应机理. 少量Pb的加入能够提高催化剂中活性粒子的分散度, 且大幅度提高催化剂对甲酸氧化的电催化活性. 当催化剂中Pd与Pb的质量比为8: 1时, 对甲酸的电氧化活性最高, 峰电流密度约为Pd/C催化剂上的180%; 而当Pd与Pb的质量比为2: 1时, 催化剂对甲酸氧化的稳定性最好.     

DNA Framework-Templated Fabrication of Ultrathin Electroactive Gold Nanosheets

Generally, two-dimensional gold nanomaterials have unique properties and functions that offer exciting application prospects. However, the crystal phases of these materials tend to be limited to the thermodynamically stable crystal structure. Herein, we report a DNA framework-templated approach for the ambient aqueous synthesis of freestanding and microscale amorphous gold nanosheets with ultrathin sub-nanometer thickness. We observe that extended single-stranded DNA on DNA nanosheets can induce site-specific metallization and enable precise modification of the metalized nanostructures at predefined positions. More importantly, the as-prepared gold nanosheets can serve as an electrocatalyst for glucose oxidase-catalyzed aerobic oxidation, exhibiting enhanced electrocatalytic activity (~3-fold) relative to discrete gold nanoclusters owing to a larger electrochemical active area and wider band gap. The proposed DNA framework-templated metallization strategy is expected to be applicable in a broad range of fields, from catalysis to new energy materials.     

Novel rGO@Fe3O4 nanostructures: An active electrocatalyst for hydrogen evolution reaction in alkaline media

Because of energy crisis, the hydrogen evolution reaction (HER) limits the feasible utilization of water splitting. Herein, we report reduced graphene-oxide (rGO) with Iron-oxide (Fe₃O₄) nanostructures as highly active electrocatalyst for HER. As-prepared [email protected]₃O₄ shows superior electrochemical responses to those of corresponding its monometallic rGO and Fe₃O₄. The overpotential of [email protected]₃O₄ has been achieved as 300 mV at 10 mA/cm² current density with a Tafel slope of 80 mV/dec. The [email protected]₃O₄ nanostructure has its stability for 24 h to reveal long term electrochemical performance.     

Ultrasonication construction of the nano-petal NiCoFe-layered double hydroxide: An excellent water oxidation electrocatalyst

Unlike other preparation methods of NiCoFe-layered double hydroxides, the present study provides a facile ultrasound method for synthesis of the nano-petal NiCoFe-layered double hydroxide (LDH) prepared under intensification frequency of 40 kHz and ultrasonic power of 305 W. The effect of time reaction on the morphology of NiCoFe-LDH was investigated using the Field Emission-Scanning Electron Microscopy images. The results show that time reaction can affect the morphology and it also showed that the optimal time for synthesis of nano-petal NiCoFe-LDH was 60 min. Then, the effect of nano-petal NiCoFe-LDH on oxygen evaluation reaction activity was studied and compared with NiCoFe-LDH-c nano paricles. Also, in order to study the effect of Co²⁺ of nano-petal NiCoFe-LDH at water oxidation, the activity of NiFe-LDH synthesized in the same conditions was investigated. The results show that nano-petal NiCoFe-LDH has low onset potential (0.46 V vs. SCE), overpotential (~227 mV) and Tafel slope (234 mV per decade) in comparison with other NiCoFe-LDH nanoparticles (synthesis using co-precipitation method and ultrasonication method within 30 and 120 min), and NiFe-LDH. Based on the obtained results, the nano-petal NiCoFe-LDH can be as a suitable electrocatalyst with good stability for water oxidation reaction in the present 0.1 M KOH media.     

Common Pitfalls of Reporting Electrocatalysts for Water Splitting

Rigorous assessment of heterogeneous electrocatalysts for electrochemical water splitting has been a critical issue mainly due to insufficient standard protocols to measure and report experimental data. In this perspective, we highlight some common pitfalls when measuring and reporting electrocatalytic data, which should be avoided to ensure the accuracy and reproducibility and to advance the water splitting field. We advocate to prevent the introduction of artefacts from the counter and reference electrodes, as well as the impurities in the electrolyte when conducting electrocatalyst activity measurements. In addition, we encourage the use of the electrochemically active surface area(ECSA)-normalized current densities to represent the intrinsic activity of the reported catalysts for a better comparison with previously known materials. Suitable ECSA measurement methods should be employed based on the nature of catalysts. Recommendations made in this perspective will hopefully assist in identifying advanced catalysts for water splitting research.     

Electrochemical Sensing of Flutamide Contained in Plasma and Urine Matrices Using NiFe2O4/rGO Nanocomposite,as an Efficient and Selective Electrocatalyst

In this article, we report on the synthesis and new employment of magnetic nickelferrite oxide nanoparticles decorated reduced graphene oxide (NiFe₂O₄/rGO) to electrochemically sensing of flutamide. The preparation of this electrocatalyst was first assessed using various analytical instrumental techniques including FT‐IR spectroscopy, X‐ray diffraction spectroscopy, energy‐dispersive X‐ray spectroscopy, and field emission scanning and transmission electron microscopy. Besides, its electrochemical performance was investigated utilizing some electrochemical methods such as cyclic and differential pulse voltammetry, and also electrochemical impedance spectroscopy. The findings of this research are especially relevant for sensing flutamide in aqueous and biological samples. At the optimized conditions, the electrochemical sensor showed a linear range of 0.24–40.0 μmol L^?1, the detection limit of 0.05 μmol L^?1 flutamide, calibration sensitivity of 1.016 μA/μmol L^?1, and repeatability and reproducibility of 1.7 % and 4.1 %, respectively. The selectivity of the method was investigated in the presence of ions, and species can generally exist in the biological medium. The resulting data of the present work represented that this type of magnetic nanocomposites is suitable for selective detection of flutamide in real samples of plasma and urine. The recoveries obtained for flutamide analyses represented lower than 5.0 percent of relative error in these real samples.