Microwave-assisted synthesis of N/S-doped CNC/SnO2 nanocomposite as a promising catalyst for oxygen reduction in alkaline media

In this study, we report an all-green approach for the synthesis of novel catalysts for oxygen reduction reaction (ORR) via a simple two-step procedure. In particular, conductive cellulose nanocrystals (CNCs) were obtained via pyrolysis, and a successive microwave-assisted hydrothermal process was employed to activate the carbon lattice by introducing sulfur (S) and nitrogen (N) dopants, and to decorate the surface with tin oxide (SnO2) nanocrystals. The successful synthesis of N/S-doped CNC/SnO2 nanocomposite was confirmed by X-ray Photoelectron Spectroscopy analysis, Energy Dispersive X-ray microanalysis, X-ray Diffraction and Field Emission Scanning Electron Microscopy. The synergistic effects of the dopants and SnO2 nanocrystals in modifying the catalytic performance were proved by various electrochemical characterizations. Particularly, the nanocomposite material reaches remarkable catalytic performance towards the ORR, close to the Pt/C benchmark, in alkaline environviment, showing promising potential to be implemented in alkaline fuel cell and metal-air battery applications

Hydrogen evolution through ammonia borane hydrolysis over iron tailored pig manure catalyst

Hydrogen storage systems have become of great interest particularly especially for those that conjugate a high storage capacity together with high safety standards. Chemical storage using amino borane has attracted a great interest and ammonia borane is playing a major role in the field due to the hydrogen storage capacity up to 19 wt %. Nevertheless, the hydrogen evolution from ammonia borane is a matter of great complexity and hydrolytic methods represent the simpler way to approach it. Actually, the ammonia borane hydrolysis is carried out by using complex catalysts not containing critical raw materials and/or noble metals. In the present work, we report the production of iron based heterogeneous catalyst support onto carbonized pig manure. The complexity of this waste stream was very helpfully to provide an active surface for the anchoring of iron nanoparticles and promoting the hydrogen evolution form hydrolysis of ammonia borane reaching a conversion of 98.3 % at 50 ◦C with an iron loading of 10 wt%. The catalytic system reduced the activation energy of the reaction up to 51 % increasing the kinetic constant of the reaction of one order of magnitude. Furthermore, the stability of the catalytic system was preserved after three cycles without appreciable changes

Homo-tandem-bifacial dye-sensitized solar cell: A new paradigm to boost photoconversion efficiency above limit

Over the last three decades, dye-sensitized solar cells (DSSCs) have received a lot of attention, reaching record efficiencies under AM 1.5G illumination slightly over 10%. However, these values are lower than other competing photovoltaic systems. The performance of DSSCs has to be further enhanced in order to have a substantial influence and application potential in the field of photovoltaics. Herein we propose a new intriguing strategy to take advantage of two concepts well known in the field of photovoltaics, such as the tandem configuration and the bifaciality, never applied at the same time to DSSCs. Thanks to the combination of these strategies, we are noteworthy able to overcome the maximum efficiency ever obtained for a traditional DSSC based on iodide/triiodide redox couple and Ru-based dye, as high as 14.96%. Our findings open the way to further enhancement with optimized DSSCs configuration