[en] Surface layer (SL) proteins are self-assembling nanosized arrays which can be recrystallized in solution or on surfaces. In this paper, we investigate the metallization, contact potential difference and conductivity of in vitro recrystallized mSbsC-eGFP tube-like assemblies for possible applications in nanobiotechnology. Treatment of mSbsC-eGFP tube-like structures with 150 mM Pt salt solution resulted in the formation of metallized SL assemblies decorated with Pt nanoparticles ( > 3 nm) which were closely packed and aggregated into metal clusters. Kelvin probe force microscopy (KPFM) measurements revealed that metallized and unmetallized SL templates showed different surface potential behaviours, demonstrating that the metal coating changes the electrostatic surface characteristics of SL assemblies. In situ conductivity measurements showed that unmetallized SL assemblies were not conductive. Metallized samples showed linear I-V dependence between - 1 and + 1 V with a conductivity of ∼ 10³ S m^-1.

[en] The doping graphene helps breaks its surface inertness providing it an intrinsic degree of catalytic activity. While single elemental doping of graphene (e.g. with N) enhances its catalytic potential, the current trend is to develop graphene doped with multiple elements. These heterodoped graphene species have improved electro-catalytic activities as compared to their corresponding single heteroatom doped counterparts because of strong charge redistribution and synergistic effects due to differences in the dopant electro-negativities. Hence, they are better suited for multiple catalytic reactions to better cope with reaction intermediates. Never-the-less, to date only a few examples exist. In this work we show it is possible to synthesize in a single CVD step, large area single- and few- layer graphene doped with oxygen and nitrogen species. Moreover, this is achieved using a solid precursor in a pure H₂ environment with growth being achieved in under 5 min. (paper)

[en] Highlights: • A novel liquid metal solvent based co-segregation (LMSCS) strategy was employed to directly fabricate 2D WC single crystals embedded in graphene film, i.e. a unique in-plane heterostructure, over a large scale in one step via chemical vapor deposition (CVD). • This 2D in-plane WC–graphene heterostructure (i-WC–G) was firstly applied in HER. Basing on the high crystallinity of the WC and utilizing the interfacial synergistic catalytic effects, the 2D i-WC–G heterostructure exhibited excellent electrocatalytic activity for the HER. • The overpotential was as low as 120 mV and the Tafel slope was 38 mV/decade, which indicated higher performance and efficiency than mainstream 2D HER catalysts. • The reproducible polarization plot even after 5000 voltammetry (CV) cycles highlighted the excellent durability of our developed 2D i-WC–G heterostructure. • Such a versatile synthesis approach will allow the fabrication of other high-quality 2D transition metal carbides (TMCs) and their embedding in in-plane structures and this will promote the practical catalytic application of metal carbides. Electrochemical water splitting is regarded as one of the most economical and eco-friendly approaches for hydrogen revolution. Developing a low-cost and earth-abundant non-noble-metal catalyst will be of the most significance. Tungsten carbide (WC) is highly promising due to its platinum (Pt) -like behavior in surface catalysis. Here we first report a liquid metal solvent based co-segregation (LMSCS) strategy to fabricate a high uniformity of 2D WC crystals embedded in graphene by chemical vapor deposition (CVD) in one step. The 2D in-plane WC–graphene heterostructures (i-WC–G) are remarkably stable under an electro-catalytic environment and ensure good interfacial synergy between the 2D WC crystallites and graphene to achieve a more effective hydrogen evolution. The overpotential is as low as 120 mV and the Tafel slope is 38 mV/dec, which indeed exhibits outstanding catalytic potential among the reported 2D material systems. Our elegant and versatile approach allows the fabrication of other high-quality 2D transition metal carbides (TMCs) and their in-plane heterostructures, which will further promote practical catalytic applications of metal carbides.

[en] Time- and temperature-resolved phase formation in the equiatomic NbTiVZr refractory high-entropy alloy has been studied in situ using high-energy synchrotron X-ray diffraction and high-speed video imaging during non-equilibrium solidification. Phase formation is shown to be dependent on the solidification conditions. When the melt is undercooled over 80 K it crystallizes as a bcc single-phase solid solution despite solute partitioning between dendrites and interdendritic regions. When the sample is for some time kept in the semisolid state, two additional bcc phases form in the interdendritic regions. The crystal growth velocity for the NbTiVZr alloy, as estimated from the high-speed videos, shows pronounced sluggish kinetics.

[en] The large specific surface area and strong adsorption ability of graphene oxide and its derivates such as partially or fully reduced graphene oxide are attractive for gas-sensing applications. Such materials are also easy to work with and are economically attractive and are thus suited to large scale fabrication. Here we compare graphene oxide with two partially reduced graphene oxide materials. In the first, ascorbic acid is used as a weak reducer and in the second, we demonstrate a new thiolation/reduction route which can also partially reduce graphene oxide and in addition provide thiol groups at the surface. We then compare the three materials for use in a simple drop-cast sensor system. The signal profile data from the three different sensors vary in shape and intensity as well as response and recovery times for the two different analytes investigated. The data suggests these parameters could be used as an array system to discriminate between analytes. (paper)