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The properties of 4H–SiC/Ni/Ti/Al/W metal contacts on n-type and p-type ion-implanted 4H–SiC layers are studied in this paper, with the aim of realizing simultaneous ohmic contact formation. The thickness of the Al film and the alloying temperature are analyzed. Specific contact resistances of 8 × 10−4 Ω cm2 and 4.1 × 10−5 Ω cm2 were achieved with multi-metal layer Ni/Ti/Al/W (80/30/110/50 nm) for n-type and p-type 4H–SiC, respectively, at an annealing temperature of 750 °C. This is for first time at such a low annealing temperature that ohmic contacts have been reported to simultaneously form on n-type and p-type 4H–SiC with satisfactory specific contact resistances. Samples were characterized using AFM, XRD, AES and TEM, and the results indicate that the presence of the W top layer facilitates lowering the surface roughness and accumulating elemental Ni and Al on the SiC side during annealing, which benefits the formation of the ohmic contacts. • Ni/Ti/Al/W on n-type and p-type 4H–SiC with various Al layer thicknesses are studied. • Ohmic contacts have been simultaneously formed on n-type and p-type 4H–SiC at 750 °C. • It's for the first time at such a low annealing temperature ohmic contacts have been formed. •The top layer W metal results in the formation of Ni2Si and Al-Rich at the interface. [ABSTRACT FROM AUTHOR]

Low-cost ceramic floor tiles were successfully produced from recycling red mud with addition of kaolin. (NH 4 ) 6 Mo 7 O 24 were used as catalyst to alter the mullitization reaction pathway and promote the growth of mullite crystals. The effects of molybdate content and sintering temperature on morphologies and performances of resultant specimens were characterized in detail. The phase evolution and microstructure observation were conducted by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results indicate the ceramic floor tile with 6 wt% (NH 4 ) 6 Mo 7 O 24 addition exhibits a flexural strength of 185.6 MPa, bulk density of 1.45 g/cm 3 and water absorption 5.5%, an intergrown microstructure composed of anisotropically grown mullite at 1180 °C. This work opens up the possibilities of the sintered ceramic as a building material since the ceramic system has good performances in flexural strength and bulk density. [ABSTRACT FROM AUTHOR]

Electrocatalytic decomposition of water using bifunctional catalysts is a potential method for clean hydrogen energy production. In order to solve the weakness of present catalysts, this study rationally designed a novel iron-nickel bifunctional electrocatalyst of Fe x Ni 1−x @C, P composites prepared by pyrolysis and phosphorus doping of a FeNi-bimetal-organic framework (FeNi-MOF). The innovative combination of FeNi bimetallic co-doping, low-temperature curing and phosphating has bred an excellent electrocatalyst for the hydrogen evolution reaction (HER) in alkaline solution. When the mass ratio of phosphate to Fe x Ni 1−x @C 250–800 was 10:1, Fe x Ni 1−x @C 250–800 , P (10:1) showed the highest hydrogen evolution activity, obtaining a low 189 mV hydrogen evolution overpotential with a Tafel slope of 91.9 mV·dec−1 at 10 mA·cm−2 current density. Meanwhile, Fe x Ni 1−x @C 250–800 , P exhibited good stability during HER process. This work would open up a novel pathway for designing efficient and stable bifunctional electrocatalysts for water electrolysis as well as sustainable chemistry applications. • A novel electrocatalyst of P-doped carbon-supported FeNi alloys (Fe x Ni 1−x @C, P) was first designed for HER. • Fe x Ni 1−x @C, P has bred an excellent electrocatalyst for the hydrogen evolution reaction in alkaline media. • P-doped carbon-supported FeNi alloys offer numerous effective active sites and accelerate electrons transfer. [ABSTRACT FROM AUTHOR]

Polycrystalline Na 0.81−x Bi x Co 1−y Mn y O 2 (0 ≤ x ≤ 0.15, 0 ≤ y ≤ 0.05) thermoelectric materials have been synthesized by solid-state reaction method using Bi and Mn as the property-manipulated substitution elements. The thermoelectric ceramics were characterized by X-ray diffraction (XRD) for phase composition, field emission scanning electron microscopy (FE-SEM) for grain morphology and cross section of sintered samples, and inductive-coupled plasma atomic emission spectroscopy (ICP-AES) for stoichiometric composition. The bulk density and average grain size of the system were also examined. The effects of partial substitution of Bi for Na and/or Mn for Co on the thermoelectric properties of Na 0.81 CoO 2 have been systematically investigated. The power factor was substantially improved by Bi and Mn co-substitution in Na 0.81 CoO 2 , and the power factor value of Na 0.66 Bi 0.15 Co 0.99 Mn 0.01 O 2 was about three times as large as that of Na 0.81 CoO 2 in the whole measured temperature range. It is evident that the Bi and Mn co-substitution is effective for optimizing thermoelectric properties of Na 0.81 CoO 2 . [ABSTRACT FROM AUTHOR]

• Metal boride was firstly proposed as a novel catalyst for VRFB. • TiB 2 nanoparticles has low cost, large surface area and good electrical conductivity. • TiB 2 displays excellent electrocatalytic performance toward V3+/V2+ couple. • TiB 2 modified cell exhibits superior VRFB energy storage performance. [Display omitted] Transition metal borides have broad application prospects in the field of electrochemistry due to their excellent physicochemical stability and electrical conductivity. In this study, metal boride (titanium boride, TiB 2) was first proposed as a novel catalyst for V3+/V2+ in vanadium redox flow battery. Nano-TiB 2 exhibits large specific surface area and great electrical conductivity, and shows excellent catalytic performance in V3+/V2+ redox reaction. The performance of TiB 2 as negative catalyst for cell was further investigated. Compared with pristine cell, TiB 2 modified cell displays much higher discharge capacity (16.9 mA h) after 50 cycles and the incipient energy efficiency increases by 6.5%. The cell with TiB 2 as the negative electrode catalyst exhibits excellent rate performance at 50–150 mA cm−2. Voltage efficiency and energy efficiency of modified cell are 8.7% and 7.5% higher than those of pristine cell at 150 mA cm−2, respectively. In conclusion, this work reveals that nano-TiB 2 is a promising catalyst for enhancing the electrochemical performance toward V3+/V2+ redox reaction for vanadium redox flow battery. [ABSTRACT FROM AUTHOR]

As a novel type of proton conductor, BaHfO 3 -based proton conductor has a promising application potential, but its poor sinterability and low conductivity limit its application as hydrogen separation membrane materials. In this paper, In and Sn co-doping BaHfO 3 strategy was adopted to further optimize its sinterability and electrical conductivity. BaHf 0.9−x In x Sn 0.1 O 3−δ (x = 0.05–0.25) proton conductors were prepared by high temperature solid state method. The results of X-ray diffraction show that In3+ and Sn4+ have been successfully doped into the lattice to form a cubic perovskite structure. BaHf 0.7 In 0.2 Sn 0.1 O 3−δ (BHSI) was facilely sintered and reached a relative density above 96.25% at 1600 °C. The scanning electron microscope observation shows that the introduction of In3+ and Sn4+ can effectively improve the sinterability and increase the grain size of the sample. High relative density and big grain size allow reducing the volume fraction of grain boundaries and increasing the electrical conductivity of BHSI. The total conductivity of BHSI in wet air reaches 5.69 × 10−3 S cm−1 at 700 °C. In addition, BHSI also shows excellent chemical stability in pure H 2 and CO 2 , 200 ppm H 2 S and water steam, and boiling water. The obtained BHSI membranes were evaluated for hydrogen separation under a mode-pure protonic conductor with external short circuit. The hydrogen separation performance of BHSI membrane was tested systematically. Gas humidification on the feed side and sweep side can obviously increase the hydrogen permeation fluxes. BHSI membrane still maintains a stable hydrogen permeation performance, even 3% CO 2 and 100 ppm H 2 S was introduced into the feed gas, respectively. • The sinterability of barium hafnate-based proton conductors is improved by In and Sn co-doping. • BaHf 0.7 In 0.2 Sn 0.1 O 3−δ exhibits the improved conductivity due to decreasing bulk and grain boundary resistances. • The BaHf 0.7 In 0.2 Sn 0.1 O 3−δ membrane shows high performance for hydrogen separation. [ABSTRACT FROM AUTHOR]