in a slow HER kinetics, while on the upside Ni offers several positive characteristics, such as high conductivity, stability and relatively high earth abundance. [1,3] Since the 1960's there has been a significant effort to improve the catalytic activity of Ni-based electrocatalysts with a large variety of promising candidates such as nickel hydroxides, dichalcogenides, phosphides, carbides, and others. [1,4] Generally, the catalytic activity can be enhanced by increasing the active surface area by tuning the catalysts morphology (e.g., production of nanowires, nanosheets, nanoparticles, etc.) and improving the intrinsic activity of the available active sites (e.g., by alloying, doping, defect engineering,

One-dimensional tellurium nanostructures can exhibit distinct electronic properties from those seen in bulk Te. The electronic properties of nanostructured Te are highly dependent on their morphology, and thus controlled synthesis processes are required. Here, highly crystalline tellurium nanowires were produced via physical vapour deposition. We used growth temperature, heating rate, flow of the carrier gas, and growth time to control the degree of supersaturation in the region where Te nanostructures are grown. The latter leads to a control in the nucleation and morphology of Te nanostructures. We observed that Te nanowires grow via the vapour–solid mechanism where a Te particle acts as a seed. Transmission electron microscopy (TEM) and electron diffraction studies revealed that Te nanowires have a trigonal crystal structure and grow along the (0001) direction. Their diameter can be tuned from 26 to 200 nm with lengths from 8.5 to 22 μm, where the highest aspect ratio of 327 was obtained for wires measuring 26 nm in diameter and 8.5 μm in length. We investigated the use of bismuth as an additive to reduce the formation of tellurium oxides, and we discuss the effect of other growth parameters.

A detailed study of the oxidation of Cu substrates was carried out under controlled conditions by regulating the pressure, atmosphere composition, process time, and temperature. By tuning the synthesis conditions, the formation of cuprous oxide (Cu2O) or cupric oxide (CuO) could be preferentially promoted. The oxidation temperature was varied from 400 to 1050 °C, and a gradual oxidation of metallic Cu to Cu2O was achieved at mild oxidation conditions (400–600 °C), while the formation of CuO was only observed at higher temperatures (≥900 °C). The surface morphology was also affected changing from a highly granular texture (400 °C) with grain sizes between 0.59 ± 0.15 µm to smooth large crystallites (≥900 °C) with a size within 2.76 ± 0.97 µm. We also show that by controlling the oxidation temperature (400–1050 °C), it is possible to tune the work function and the ionization potential of the resulting Cu2O/CuO film, properties that are important for various optoelectronic applications.

We report on the spray-coating fabrication of a complete metal-free light-emitting electrochemical cell featuring PEDOT:PSS as both electrodes, which is semi-transparent in the off-state and delivers bright emission in the on-state.