Atomic Layer Deposition of Nanolayered Carbon Films

In this paper, carbon thin films were grown using the plasma-enhanced atomic layer deposition (PE-ALD). Methane (CH4) was used as the carbon precursor to grow the carbon thin film. The grown film was analyzed by the high-resolution transmission electron micrograph (TEM), X-ray photoelectron spectroscopy (XPS) analysis, and Raman spectrum analysis. The analyses show that the PE-ALD-grown carbon film has an amorphous structure. It was found that the existence of defective sites (nanoscale holes or cracks) on the substrate of copper foil could facilitate the formation of nanolayered carbon films. The mechanism for the formation of nanolayered carbon film in the nanoscale holes was discussed. This finding could be used for the controlled growth of nanolayered carbon films or other two-dimensional nanomaterials while combining with modern nanopatterning techniques.

Restricted growth and grain boundary reinforcement of MAPbBr3 film by graphene quantum dots with enhanced luminescence and stability

Organic-inorganic hybrid perovskite (OIHP) attracted much attention in the optoelectronic applications owing to its high yield, adjustable color and good mono-chromaticity. However, the defective sites at MAPbBr3 film boundaries greatly jeopardize their luminescent property. In this study, graphene quantum dots (GQDs) are incorporated into the MAPbBr3 film and pushed to the grain boundaries during perovskite crystallization via a modified freeze casting approach. The rich carboxyl groups of GQDs interact with the dangling lead atoms at grain boundaries, thus reducing non-radiative recombination centers within the film. On the other hand, GQDs create additional nucleation sites, which helps to form a uniformly covered luminescent film with small grains. As a result, the incorporation of GQDs increases the photoluminescence (PL) intensity of the emission film by about six times and well preserves the crystal phase for 36-day storage in ambient air.

Operando mechanistic and dynamic studies of N/P co-doped hard carbon nanofibers for efficient sodium storage

In-situ Raman and electrochemical results reveal that Na+ adsorb on the surface/defective sites of the N/P-HCNF and insert randomly into its turbostratic nanodomains in a dilute state without the staging...

Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction

Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (nitrogenase), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N2 molecules, but it is necessary to realize features present in the nitrogenase mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to future sustainable energy and chemistry beyond fossil fuels.

Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction

Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (Nitrogenase), electrocatalysis, metal-complexes and plasma-catalysis are analysed and compared. It is evidenced that differently from what present in thermal and plasma-catalysis, the electrocatalysis path requires not only the direct coordination and hydrogenation of undissociated N2 molecule, but to realize a series of features present in the Nitrogenase mechanism. There is the need of i) a multi-electron and -proton simultaneous transfer, not as sequential steps, ii) forming bridging metal hydride species, iii) generate intermediates stabilized by bridging multiple metal atoms, iv) have the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and relations with CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to a future sustainable energy and chemistry beyond fossil fuels.