Ultrathin B-C-N layers grown on Ti substrates are investigated as efficient anodes for electrochemical water splitting. A fast and direct synthetic route has been used, based on plasma-enhanced chemical vapour deposition with Methylamine Borane as a singlesource molecular precursor. The effect of growth time on the morphological and structural properties and on the chemical composition of the layers has been investigated by scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy and transmission electron microscopy coupled with electron energy loss spectroscopy. Flat B-C-N layers on top of an amorphous titanium oxide layer present at the Ti surface have been obtained by using short growth times, while longer growth times give rise to core/ shell structures formed by vertical wall B-C-N layers and titanium carbonitride phases. The obtained layers present enhanced electrocatalytic activity for the oxygen evolution reaction in alkaline aqueous solutions. Moreover, owing to their ultrathin nature, the B-C-N layers preserve the photocurrents of the underlying titanium oxide layer, acting as transparent electrodes with

A suitable way to modify the electronic properties of graphene—while maintaining the exceptional properties associated with its two-dimensional (2D) nature—is its functionalisation. In particular, the incorporation of hydrogen isotopes in graphene is expected to modify its electronic properties leading to an energy gap opening, thereby rendering graphene promising for a widespread of applications. Hence, deuterium (D) adsorption on free-standing graphene was obtained by high-energy electron ionisation of D2 and ion irradiation of a nanoporous graphene (NPG) sample. This method allows one to reach nearly 50 at.% D upload in graphene, higher than that obtained by other deposition methods so far, towards low-defect and free-standing D-graphane. That evidence was deduced by X-ray photoelectron spectroscopy of the C 1s core level, showing clear evidence of the D-C sp3 bond, and Raman spectroscopy, pointing to remarkably clean and low-defect production of graphane. Moreover, ultraviolet photoelectron spectroscopy showed the opening of an energy gap in the valence band. Therefore, high-energy electron ionisation and ion irradiation is an outstanding method for obtaining low defect D-NPG with a high D upload, which is very promising for the fabrication of semiconducting graphane on large scale.

Graphane is formed by bonding hydrogen (and deuterium) atoms to carbon atoms in the graphene mesh, with modification from the pure planar sp 2 bonding towards an sp 3 configuration. Atomic hydrogen (H) and deuterium (D) bonding with C atoms in fully freestanding nano porous graphene (NPG) is achieved, by exploiting low-energy proton (or deuteron) non-destructive irradiation, with unprecedented minimal introduction of defects, as determined by Raman spectroscopy and by the C 1s core level lineshape analysis. Evidence of the H-(or D-) NPG bond formation is obtained by bringing to light the emergence of a H-(or D-) related sp 3 -distorted component in the C 1s core level, clear fingerprint of H-C (or D-C) covalent bonding. The H (or D) bonding with the C atoms of free-standing graphene reaches more than 1/4 (or 1/3) at% coverage. This non-destructive H-NPG (or D-NPG) chemisorption is very stable at high temperatures up to about 800 K, as monitored by Raman and x-ray photoelectron spectroscopy, with complete healing and restoring of clean graphene above 920 K. The excellent chemical and temperature stability of H-(and D-) NPG opens the way not only towards the formation of semiconducting graphane on large-scale samples, but also to stable graphene functionalisation enabling futuristic applications in advanced detectors for the βspectrum analysis.

Tuning the electrocatalytic properties of MoS 2 layers can be achieved through different paths, such as reducing their thickness, creating edges in the MoS 2 flakes, and introducing S-vacancies. We combine these three approaches by growing MoS 2 electrodes by using a special salt-assisted chemical vapor deposition (CVD) method. This procedure allows the growth of ultrathin MoS 2 nanocrystals (1−3 layers thick and a few nanometers wide), as evidenced by atomic force microscopy and scanning tunneling microscopy. This morphology of the MoS 2 layers at the nanoscale induces some specific features in the Raman and photoluminescence spectra compared to exfoliated or microcrystalline MoS 2 layers. Moreover, the S-vacancy content in the layers can be tuned during CVD growth by using Ar/H 2 mixtures as a carrier gas. Detailed optical microtransmittance and microreflectance spectroscopies, micro-Raman, and X-ray photoelectron spectroscopy measurements with sub-millimeter spatial resolution show that the obtained samples present an excellent homogeneity over areas in the cm 2 range. The electrochemical and photoelectrochemical properties of these MoS 2 layers were investigated using electrodes with relatively large areas (0.8 cm 2 ). The prepared MoS 2 cathodes show outstanding Faradaic efficiencies as well as long-term stability in acidic solutions. In addition, we demonstrate that there is an optimal number of Svacancies to improve the electrochemical and photoelectrochemical performances of MoS 2 .