Einfluss der Rauheit auf das Verschleißverhalten von DLC-Schichten

Der niedrige Reibwert und geringe Verschleiß von amorphen Kohlenwasserstoffschichten wird üblicherweise mit einem Transferfilm auf dem Gegenkörper und einer Phasenumwandlung in Verbindung gebracht. In Überrollversuchen wurde der Einfluss der anfänglichen Rauheit auf das Verschleißverhalten untersucht. Der Verschleiß verläuft linear mit der Zeit und hängt dabei vor allem von der Anfangsrauheit ab, er erinnert sich trotz Einglättung der Oberfläche an seine Anfangsrauheit, obwohl sich unabhängig von der Anfangsrauheit eine feste Betriebsrauheit eingestellt hat. Dabei wird ein Aufbau eines Transferfilms sowie eine Absenkung des sp3- Anteils auf dem Transferfilm beobachtet. Die Dicke des Transferfilms hängt dabei ebenfalls von der Anfangsrauheit ab, hat aber scheinbar keinen direkten Einfluss auf die Verschleißtiefe

Preparation and characterization of GaP semiconductor electrodes for photoelectrochemical water splitting

Abstractp-type GaP was systematically examined for photoelectrochemical water splitting. The influence of wet chemical etching and the difference of electrochemical deposition and physical vapor deposition of platinum were investigated. Therefore, each preparation step of GaP was studied by photoelectron emission spectroscopy, atomic force microscopy and photoelectrochemical methods

Silicon based tandem cells: novel photocathodes for hydrogen production

A photovoltaic tandem cell made of amorphous silicon (a-Si) and microcrystalline silicon (μc-Si) was investigated as a photocathode for hydrogen evolution in a photoelectrochemical device. The electronic and electrochemical properties of the samples were characterized using X-ray photoemission spectroscopy (XPS) and cyclic voltammetry (CV), whereas the morphology of the surface in contact with the electrolyte was investigated by scanning electron microscopy (SEM). The electric efficiency of the tandem cell was determined to be 5.2% in a photoelectrochemical (PEC) setup in acidic solution which is only about half of the photovoltaic efficiency of the tandem cell. A significant improvement in efficiency was achieved with platinum as a catalyst which was deposited by physical vapour deposition (PVD) under ultra-high vacuum (UHV) conditions

Solar water splitting with earth-abundant materials using amorphous silicon photocathodes and Al/Ni contacts as hydrogen evolution catalyst

An all earth-abundant and precious metal-free photocathode based on a low-temperature fabricated amorphous silicon tandem junction is demonstrated to be an efficient device for solar water splitting. With a particular designed Al/Ni layer stack as photocathode/electrolyte contact an onset potential for cathodic photocurrent of 1.7 V vs. RHE and a saturation photocurrent density of 7.2 mA/cm2 were achieved. For a high-cost alternative with a Ag/Pt layer stack an even higher photocathode performance is demonstrated. Above all we present an approach for a dedicated photovoltaic and electrochemical development for solar water splitting