Phosphorus and Yttrium Codoped Co(OH)F Nanoarray as Highly Efficient and Bifunctional Electrocatalysts for Overall Water Splitting

Rational design and synthesis of bifunctional electrocatalysts with high efficiency and low‐cost for overall water splitting is still a challenge. A simple approach is reported to prepare a phosphorus and yttrium codoped cobalt hydroxyfluoride (YP‐Co(OH)F) nanoarray on nickel foam, which displays high‐performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction in alkaline solution. The codoping of yttrium and phosphorus into Co(OH)F leads to a tuned electronic environment and favorable electron transfer, thus resulting in superior water splitting activity. The YP‐Co(OH)F electrode only requires an overpotential of 238 mV to reach a current density of 10 mA cm^?2 (η₁₀), much smaller than RuO₂ (302 mV). Moreover, it displays an overpotential of 55 mV at η₁₀ for HER, similar to that of Pt/C. When YP‐Co(OH)F is used as both anode and cathode in a two‐electrode configuration, it only demands a cell potential of 1.54 V at η₁₀, lower than the IrO₂||Pt/C couple (1.6 V) as well as other recently reported electrocatalysts. It even maintains stable water splitting for 300 h. Such a two‐electrode device can be easily driven by a 1.5 V silicon solar cell in sunlight, proving the potential of the promising catalyst for large‐scale electrolytic water splitting.     

甘氨双唑钠对离体V79细胞的放射增敏作用

以离体细胞克隆形法进一步研究了甘氨双唑钠对乏氧Ｖ７９细胞的放射增敏作用。结果表明：ＳＧＤＤ的毒性较低，且对乏氧细胞的毒性比有氧时强。它对有氧细胞无增敏作用，但在乏氧情况下，对Ｖ７９细胞有明显的放射增敏效果，当ＳＧＤＤ在１．３８ｍｍｏｌ／Ｌ以下时，其ＳＥＲ值浓度的增加而增高，Ｃ１．６＝０．４８ｍｍｏｌ／Ｌ，ＳＥＦ最大值２．３时的浓度为１．３８ｍｍｏｌ／Ｌ，不到ＩＤ５０的１／７０。     

Controllable preparation of Ti/TiO2-NTs/PbO2–CNTs–MnO2 layered composite materials with excellent electrocatalytic activity for the OER in acidic media

High oxygen evolution overpotential and low corrosion resistance are the main challenges for oxygen evolution materials in acidic media. In this study, a novel composite material, Ti/TiO₂-NTs/PbO₂–CNTs–MnO₂, with high oxygen evolution electrocatalytic activity was successfully prepared. First, TiO₂ nanotubes (TiO₂-NTs) were synthesized in situ on a Ti sheet via anodization and used as an intermediate layer. Subsequently, the adhesion and conductivity of the TiO₂-NTs layer were increased through additional anodization, annealing, and electrochemical reduction. Finally, PbO₂ was electrodeposited with a constant current in a lead acetate medium and doped with carbon nanotubes (CNTs) and MnO₂. The surface morphology, phase composition, and electrochemical performance of the composite materials were investigated. Notably, in an acidic electrolyte (150 g/L H₂SO₄), Ti/TiO₂-NTs/PbO₂–CNTs–MnO₂ exhibited good stability (30 h) and a low oxygen evolution overpotential of 410 mV at 50 mA/cm², which is almost equivalent to that of precious metals (RuO₂ and IrO₂) and 499 mV lower than that of the industrial Pb–0.76 wt% Ag alloy. The outstanding performance is mainly attributed to the high aspect ratio of the TiO₂-NT structure, synergistic effects of the active particles, and inherently good electrochemical properties of the active particles. Therefore, this study provides a new synthetic route for oxygen evolution materials in acidic media.     

Copper molybdate nanoparticles for electrochemical water splitting application

Two different phases of copper molybdate nanoparticles such as Cu₃Mo₂O₉ and Cu₆Mo₅O₁₈ were synthesized through schematic hydrothermal treatment. The obtained product morphology was explored by using surfactants like sodium lauryl sulfate (SDS) and polyvinylpyrrolidone (PVP). The structural, optical, vibrational and morphological properties were confirmed employing standard characterization techniques. Rectangular nanoflakes of the obtained product were confirmed by employing Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies. Selected area electron diffraction (SAED) pattern confirms obtained product crystalline nature. The better morphology controlled sample gives higher 227 mA/g current density at 10 mV/s and small 184 V overpotential. Long duration stability over 16 h was exhibited by Cu₆Mo₅O₁₈ electrode. Hence, Cu₆Mo₅O₁₈ electrode shows better electrochemical activity with stunning low overpotential. It would be suggested that PVP surfactant is quite optimum to produce efficient Cu₆Mo₅O₁₈ catalysts for electrochemical water splitting applications.     

Thin porous nanosheets of NiFe layered-double hydroxides toward a highly efficient electrocatalyst for water oxidation

NiFe layered double hydroxides (NiFe-LDH) are low cost and earth abundant electrocatalysts for oxygen evolution reaction (OER). Herein, the NiFe-LDH nanosheets induced by ZIF-67 (NiFe-LDH/ZIF-67) were prepared via a coupling method of a self-sacrificing template method and a co-precipitation method. Atomic force microscope and field emission transmission electron microscopy analysis indicate that NiFe-LDH/ZIF-67 consist of thin porous nanosheets. X-ray photoelectron spectra analysis show that NiFe-LDH/ZIF-67 contains more oxygen vacancies than pristine NiFe-LDH. The overpotential of NiFe-LDH/ZIF-67 is 222 mV at 10 mA cm⁻² for OER, lower than that of ZIF-67, pristine NiFe-LDH, and the commercial RuO₂, indicating that its high electrocatalytic activity for OER. The high electrocatalytic activity of NiFe-LDH/ZIF-67 may be attributed to its thin porous nanosheet structure, which is derived from the structural influence of ZIF-67 and the coupling effect of a self-sacrificing template method and a co-precipitation method.     

Binary spindle-like cobalt–iron layered-double hydroxide as an efficient electrocatalyst for oxygen evaluation reaction

In this research, inexpensive transition metals are used for electrocatalytic oxygen evolution reactions. Nickel foam was modified as a substrate using spindle-like Co–Fe LDH. XRD, FE-SEM, EDS, and elemental mapping techniques are used for characterization. Based on LSV results, overpotentials of 280 and 355 mV were obtained at 10 and 100 mA cm^?2, respectively. To evaluate the stability of electrocatalyst, cyclic voltammetry, chronoamperometry (at constant potentials of 1.55 and 1.65 V vs. RHE), and chronopotentiometry (at applied current densities of 10 and 100 mA cm^?2) methods are used. All stability tests were performed consecutively using one electrode. Current density increased by 0.05% after performing 500 CV cycles. The catalytic performance was enhanced during the chronoamperometry analysis. However, the potential decreased slightly by less than 0.44% after 7200 s at 100 mA cm^?2 in chronopotentiometry analysis. The high durability and current density ensure the efficient performance of the as-prepared electrocatalyst in water splitting process.     

Gold-supported magnetron sputtered Ir thin films as OER catalysts for cost-efficient water electrolysis

This work presents a research on the preparation of thin composite catalytic films in which an essential part of the efficient but expensive Ir is substituted by Au sub-layer using the preparation method of direct current magnetron sputtering (DCMS). The aim is to investigate the influence of the Au sub-layer on the catalytic activity toward oxygen evolution reaction (OER) of water electrolysis. The properties of the sputtered films are studied using X-ray diffraction (XRD) and electrochemical methods of cyclic voltammetry, quasi steady state polarization and chronoamperometry. It is found that by proper variations in the films thickness it is possible to realize synergetic effects leading to essential decrease in Ir loading and the cost of catalysis without sacrifice in efficiency.     

Hydrogen evolution reaction and electronic structure calculation of two dimensional bismuth and its alloys

We present a systematic ab initio study of atomic hydrogen and oxygen adsorption on bismuthene monolayer and its alloys with arsenic and antimony through electronic structure calculations based on density functional theory within generalized gradient approximation. We systematically investigated the preferable adsorption site for hydrogen and oxygen atom on 2D Bi, BiAs and BiSb. It was found that the hydrogen atom prefers top site of bismuth atom and oxygen atom prefers to reside in the hexagonal ring of these 2D bismuth alloys. The free energy calculated from the individual adsorption energy for each monolayer subsequently guides us to predict the best suitable catalyst among the considered 2D monolayers. The 2D BiSb serves better for hydrogen evolution reaction (HER) with hydrogen adsorption energy as ?1.384 eV while 2D BiAs is suitable for oxygen evolution reaction (OER) with oxygen adsorption energy as ?1.092 eV. We further investigated the effects of the adsorbate atom on the electronic properties of 2D Bi, BiAs and BiSb. The adsorption of oxygen on 2D BiAs and BiSb was shown to reduce the bulk band gap by 40.56 and 67.79% respectively which will be advantageous for the observation of Quantum Spin Hall effect at ambient conditions.     

Low-pressure-plasma-processed NiFe-MOFs/nickel foam as an efficient electrocatalyst for oxygen evolution reaction

A NiFe bimetallic metal organic framework (MOF) deposited on nickel foam and processed by low-pressure plasmas with 95%Ar+5%H₂, pure Ar, and 95%Ar+5%O₂ gases is used as an electrocatalyst for the oxygen evolution reaction. An alkaline solution (1 M KOH) with 95%Ar+5%H₂ plasma processed NiFe-MOFs/NF exhibits the best electrocatalytic performance with the lowest overpotential of 149 mV at a current density of 10 mA cm^?2 and a Tafel slope of 54 mV dec^?1. Furthermore, electrical impedance spectroscopy and cyclic voltammetry show that after 95%Ar+5%H₂ plasma treatment, the interfacial impedance greatly reduces, and the electrical double-layer capacitance slightly increased.     

TiO2 photocatalyst with single and dual noble metal co-catalysts for efficient water splitting and organic compound removal

Photocatalysts can be used both for air cleaning and solar energy harvesting through water splitting. However, pure TiO₂ photocatalysts are often inefficient and therefore co-catalysts are needed to improve the yield. To achieve this goal, we prepared TiO₂ and deposited Pt, Ir and Ru co-catalysts on its surface. Two base TiO₂ nanoparticles were used: P25 and rutile TiO₂ synthesized via hydrothermal method. Co-catalysts were deposited by wet impregnation technique using single element and a combination of two elements (Pt and Ir or Pt and Ru), followed by annealing in either air or H₂/Ar. Annealing in reducing atmosphere increased the photocatalytic activity of oxidation of isopropanol compared to annealing in air. We demonstrated a clear influence of the co-catalysts on the photocatalytic degradation of isopropanol and on electrochemical water-splitting reaction. The platinum-containing samples showed the best HER activity.