Hexagonal boron nitride (hBN) has emerged as a promising two-dimensional (2D) material for photonics device due to its large bandgap and flexibility in nanophotonic circuits. Here, we report bright and localized luminescent centres can be engineered in hBN monolayers and flakes using laser irradiation. The transition from hBN to cBN emerges in laser irradiated hBN large monolayers while is absent in processed hBN flakes. Remarkably, the colour centres in hBN flakes exhibit room temperature cleaner single photon emissions with g2(0) ranging from 0.20 to 0.42, a narrower line width of 1.4 nm and higher brightness compared with monolayers. Our results pave the way to engineering deterministic defects in hBN induced by laser pulse and show great prospect for application of defects in hBN used as nano-size light source in photonics.

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This critical review focuses on advanced recycling strategies to enable or increase recovery of chemical elements present in waste printed circuit boards (WPCBs). Conventional recycling involves manual removal of high value electronic components (ECs), followed by raw crushing of WPCBs, to recover main elements (by weight or value). All other elements remain unrecovered and end up highly diluted in post-processing wastes or ashes. To retrieve these elements, it is necessary to enrich the waste streams, which requires a change of paradigm in WPCB treatment: the disassembly of WPCBs combined with the sorting of ECs. This allows ECs to be separated by composition and to drastically increase chemical element concentration, thus making their recovery economically viable. In this report, we critically review state-of-the-art processes that dismantle and sort ECs, including some unpublished foresight from our laboratory work, which could be implemented in a recycling plant. We then identify research, business opportunities and associated advanced retrieval methods for those elements that can therefore be recovered, such as refractory metals (Ta, Nb, W, Mo), gallium, or lanthanides, or those, such as the platinum group elements, that can be recovered in a more environmentally friendly way than pyrometallurgy. The recovery methods can be directly tuned and adapted to the corresponding stream.

Liquid-liquid extraction is a complex chemical purification process, which is associated with many thermodynamic and kinetic values. This makes its application in the recycling industry difficult, as it deals with waste streams that have highly variable compositions. In this regard, modelling an extraction process using microfluidics proves to be a useful approach to allow rapid adaptation to such composition changes, if development can be shown to be more accurate, faster, and safer than the classical batch approach with separate analysis. Here, the first automated microfluidic tool integrated with online X-ray fluorescence (XRF) is reported to study liquid-liquid extraction processes by enabling metal concentration quantification. The measurement is automated and performed for both aqueous and organic phases to improve accuracy.Overall, this fully automated approach shows that: (i) Thermodynamic and kinetic values associated with these processes can rapidly and efficiently be obtained simultaneously (in less than 13 hours with a resulting liquid use of less than 20 mL). (ii) Numerical simulations are consistent with the experimental data and provide rare insights regarding the respective contributions to the overall kinetic of the extraction system.

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Graphene nanogap systems are promising research tools for molecular electronics, memories, and nanodevices. Here, a way to control the propagation of nanogaps in monolayer graphene during electroburning is demonstrated. A tightly focused femtosecond laser beam is used to induce defects in graphene according to selected patterns. It is shown that, contrary to the pristine graphene devices where nanogap position and shape are uncontrolled, the nanogaps in prepatterned devices propagate along the defect line created by the femtosecond laser. Using passive voltage contrast combined with atomic force microscopy, the reproducibility of the process with a 92% success rate over 26 devices is confirmed. Coupling in situ infrared thermography and finite element analysis yields a real-time estimation of the device temperature during electrical loading. The controlled nanogap formation occurs well below 50 °C when the defect density is high enough. In the perspective of graphene-based circuit fabrication, the availability of a cold electroburning process is critical to preserve the full circuit from thermal damage.

Liquid-liquid extraction processes, characterized on-line by instrumented microfluidic platform, significantly enhance the development of predictive thermodynamic models, such as ienaics, and lay the foundations for new approaches to improve kinetic models which combine transport and chemistry. Instrumented microfluidics enables precise measurement of free energy of transfer of species at equilibria and their associated characteristic transfer times, faster and more accurately than its batch mode counterpart. Computer controlled and fully automatized, our platform illustrated the kinetic differences of high extraction's of Ytterbium (Yb) and Iron (Fe), two elements reported as having very different extraction efficiencies due to different molecular forces competing with complexation when modifiers are used together with extractants. Once collected and processed, the kinetics show two distinct behaviors of these two metallic elements: depending on the temperature, Fe could display a very slow extraction profile when compared to Yb.