HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The electrochemical splitting of water provides an elegant way to store renewable energy, but it is limited by the cost of the noble metals used as catalysts. Among the catalysts used for the reduction of water to hydrogen, MoS 2 has been identified as one of the most promising materials as it can be engineered to provide not only a large surface area but also an abundance of unsaturated and reactive coordination sites. Using Mo[NMe 2 ] 4 and H 2 S as precursors, a desired thickness of amorphous MoS 2 can be deposited on TiO 2 nanotubes by atomic layer deposition. The identity and structure of the MoS 2 film are confirmed by spectroscopic ellipsometry, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The electrocatalytic performance of MoS 2 is quantified as it depends on the tube length and the MoS 2 layer thickness through voltammetry, steady-state chronoamperometry, and electrochemical impedance spectroscopy. The best sample reaches 10 mA/cm 2 current density at 189 mV overpotential in 0.5 M H 2 SO 4 . All of the various geometries of our nanostructured electrodes reach an electrocatalytic proficiency comparable with the state-of-the-art MoS 2 electrodes, and the dependence of performance parameters on geometry suggests that the system can even be improved further.

Extending plasmonics into the ultraviolet range imposes the use of aluminum to achieve the best optical performance. However, water corrosion is a major limiting issue for UV aluminum plasmonics, as this phenomenon occurs significantly faster in presence of UV light, even at low laser powers of a few microwatts. Here we assess the performance of nanometer-thick layers of various metal oxides deposited by atomic layer deposition (ALD) and plasma-enhanced chemical vapor deposition (PECVD) on top of aluminum nanoapertures to protect the metal against UV photocorrosion. The combination of a 5 nm Al2O3 layer covered by a 5 nm TiO2 capping provides the best resistance performance, while a single 10 nm layer of SiO2 or HfO2 is a good alternative. We also report the influence of the laser wavelength, the laser operation mode and the pH of the solution. Properly choosing these conditions significantly extends the range of optical powers for which the aluminum nanostructures can be used.As application, we demonstrate the label-free detection of streptavidin proteins with improved signal to noise ratio. Our approach is also beneficial to promote the long-term stability of the aluminum nanostructures. Finding the appropriate nanoscale protection against aluminum corrosion is the key to enable the development of UV plasmonic applications in chemistry and biology.