Recent theoretical and experimental studies have indicated the existence of a new stable phase of carbon with mixed sp² and sp³ hybridized bonds—diaphite. Such a two-layered structure with sp²/sp³ bonds may be observed after the photostimulation of highly oriented pyrolytic graphene with femtosecond laser pulses. This hidden multistability of graphene may be used to create a semiconducting phase immersed in the semimetallic continuum, resulting in bandgap opening. We demonstrate that bandgap opening and light emission from graphene is possible using continuous-wave laser beams with wavelengths from the visible (405 nm) to the near-infrared range (975 nm). We demonstrate that without the application of cooling, the effective temperature of the emitting sample remains lower than 900 K, which is far below the value predicted by the theory of black-body radiation. Moreover, light emission from a graphene sample may be observed at temperatures as low as 10 K.

In this work, a new bulk Li_3.6PO_3.4N_0.6 crystalline polymorph has been prepared from low-cost precursors, following a simple ball-milling procedure. The densified powder exhibits a conductivity of 5.0 × 10^–6 S cm^–1 at 70 °C and an electrochemical stability allowing operation with high-voltage materials up to 5.0 V vs Li/Li⁺. Stripping and plating of lithium in a symmetric cell demonstrates the forthcoming bulk application of LiPON in electrochemical devices. Widening the use of lithium phosphorus oxynitride compositions to bulk solid-state batteries will have relevant implications because of its unique compatibility with both high-voltage electroactive materials and lithium metal and its low density.

Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

In the present study, alkaline earth metal scheelite-type ABO₄ compounds (A = Ca, Sr, and Ba; B = Mo and W) synthesized by a hydrothermal method were systematically studied. The as-obtained photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, UV–vis diffuse reflectance (DR/UV–vis) spectroscopy, photoluminescence, and thermoluminescence (TL) spectroscopy together with charge carrier lifetime measurements, electron paramagnetic resonance (EPR) spectroscopy, and electrochemical impedance spectroscopy (EIS). The photocatalytic activity was studied in the reaction of phenol degradation under simulated solar light. The obtained tungstates and molybdates revealed excellent photocatalytic activity despite the low surface area and wide bandgap typical for insulators. The mechanism of phenol degradation proceeded through hydroquinone and catechol formation in the presence of hydroxyl and superoxide radicals. The presence of electron traps allowed absorption of light with lower energy than resulting from the absorption edge. BaWO₄ and SrWO₄, with the most extended average carrier lifetime, were the most efficient photocatalysts from the obtained series. In general, molybdates exhibited lower photocatalytic activity toward phenol degradation due to deeper trap states and lower average charge carrier lifetimes than tungstates. Additionally, electrochemical studies demonstrated that molybdates exhibit more insulating behavior than tungstates. The overall results showed that wide-bandgap semiconductors, mainly tungstates, can be applied as earth-abundant photocatalytic materials for the degradation of persistent organic pollutants.