The effect of the incorporation of Cs ⁺ and Br ⁻ in FAPbl ₃ investigated by Raman spectroscopy.

The past decade has seen enormous efforts in the investigation and development of reduced graphene oxide (GO) and its applications. Reduced graphene oxide (rGO) derived from GO is known to have relatively inferior electronic characteristics when compared to pristine graphene. Yet, it has its significance attributed to high-yield production from inexpensive graphite, ease of fabrication with solution processing, and thus a high potential for large-scale applications and commercialization. Amongst several available approaches for GO reduction, the mature use of plasma technologies is noteworthy. Plasma technologies credited with unique merits are well established in the field of nanotechnology and find applications across several fields. The use of plasma techniques for GO development could speed up the pathway to commercialization. In this report, we review the state-of-the-art status of plasma techniques used for the reduction of GO-films. The strength of various techniques is highlighted with a summary of the main findings in the literature. An analysis is included through the prism of chemistry and plasma physics.

Formamidinium lead iodide (FAPbI ₃ ) can exhibit polymorphism at ambient conductions. Three different structural configurations and their thermally activated phase transitions are identified by temperature dependent micro-Raman spectroscopy.

The crystallisation of sputter-deposited, amorphous In₂O₃:H films was investigated. The influence of deposition and crystallisation parameters onto crystallinity and electron hall mobility was explored. Significant precipitation of metallic indium was discovered in the crystallised films by electron energy loss spectroscopy. Melting of metallic indium at ~160 °C was suggested to promote primary crystallisation of the amorphous In₂O₃:H films. The presence of hydroxyl was ascribed to be responsible for the recrystallization and grain growth accompanying the inter-grain In-O-In bounding. Metallic indium was suggested to provide an excess of free electrons in as-deposited In₂O₃ and In₂O₃:H films. According to the ultraviolet photoelectron spectroscopy, the work function of In₂O₃:H increased during crystallisation from 4 eV to 4.4 eV, which corresponds to the oxidation process. Furthermore, transparency simultaneously increased in the infraredspectral region. Water was queried to oxidise metallic indium in UHV at higher temperature as compared to oxygen in ambient air. Secondary ion mass-spectroscopy results revealed that the former process takes place mostly within the top ~50 nm. The optical band gap of In₂O₃:H increased by about 0.2 eV during annealing, indicating a doping effect. This was considered as a likely intra-grain phenomenon caused by both (In⁰)_O^•• and (OH⁻)_O^• point defects. The inconsistencies in understanding of In₂O₃:H crystallisation, which existed in the literature so far, were considered and explained by the multiplicity and disequilibrium of the processes running simultaneously.

Carbon is considered to exist in three basic forms: diamond, graphite/graphene/fullerenes, and carbyne, which differ in a type of atomic orbitals hybridization. Since several decades the existence of the fourth basic carbon allotropic form with the face-centered cubic (fcc) crystal lattice has been a matter of discussion despite clear evidence for its laboratory synthesis and presence in nature. Here, we obtain this carbon allotrope in form of epitaxial films on diamond in a quantity sufficient to perform their comprehensive studies. The carbon material has an fcc crystal structure, shows a negative electron affinity, and is characterized by a peculiar hybridization of the valence atomic orbitals. Its bandgap (~6 eV) is typical for insulators, whereas the noticeable electrical conductivity (~0.1 S m⁻¹) increases with temperature, which is typical for semiconductors. Ab initio calculations explain this apparent contradiction by noncovalent sharing p-electrons present in the uncommon valence band structure comprising an intraband gap. This carbon allotrope can create a new pathway to ‘carbon electronics’ as the first intrinsic semiconductor with an ultra-wide bandgap.

A single step deposition technique of Pt/C films for electrocatalytic applications is presented. The hollow cathode gas flow sputtering (GFS) method allows a catalyst production within few minutes without further steps. The herein presented films consist of small Pt nanocrystals (2–5 nm) deposited in a matrix of nanocrystalline carbon. The films show a low and stable overpotential under acidic conditions in the hydrogen evolution reaction (HER). Relatively low Pt‐mass activity (<1 mA/μg_Pt) is attributed to the yet too high Pt‐content in the films. Another issue discovered in this work is a non‐graphitic state of carbon resulting in its high resistivity. Still, the GFS deposition technique providing by nature high deposition rates and a substance‐to‐material yield of 80–90 % is advantageous than other sputtering techniques and especially chemical methods in that sense. This technique is scalable to areas in the range of square meters and thus represents an attractive way to efficiently produce large‐scale cathode coatings for industrial electrolysers.