The rational design of heterojunctions based on metal halide perovskites (MHPs) is an effective route to create novel photocatalysts to run relevant solar‐driven reactions. In this work, an experimental and computational study on the synergic coupling between a lead‐free Cs₃Bi₂Br₉ perovskite derivative and g‐C₃N₄ is presented. A relevant boost of the hydrogen photogeneration by more than one order of magnitude is recorded when going from pure g‐C₃N₄ to the Cs₃Bi₂Br₉/g‐C₃N₄ system. Effective catalytic activity is also achieved in the degradation of the organic pollutant with methylene blue as a model molecule. Based upon complementary experimental outputs and advanced computational modeling, a rationale is provided to understand the heterojunction functionality as well as the trend of hydrogen production as a function of perovskite loading. This work adds further solid evidence for the possible application of MHPs in photocatalysis, which is emerging as an extremely appealing and promising field of application of these superior semiconductors.

One of the most recent developments at the forefront of nanotechnology is the attempt to exploit quantum phenomena in nanometer scale materials, exploring novel applications of quantum effects. An effective exploitation of quantum phenomena must necessarily pass through a deep understanding of how to generate, manipulate and characterize coherent superposition of quantum states in the nanosystems. However, despite the lively interest on this topic, the study of coherent effects in nanomaterials still represents relatively unexplored territory. Here we report an investigation on the ultrafast coherent dynamics of colloidal CdSe quantum dots (QDs) by mean of two-dimensional electronic spectroscopy (2DES). The time evolution of specific coherent superpositions of fine structure levels in these nanomaterials is clearly demonstrated. The obtained results represent an important step forward towards a deeper understanding of quantum properties of nanomaterials.

Currently, intensive research efforts focus on the fabrication of meso-structures of assembled colloidal quantum dots (QDs) with original optical and electronic properties. Such collective features originate from the QDs coupling, depending on the number of connected units and their distance. However, the development of general methodologies to assemble colloidal QD with precise stoichiometry and particle-particle spacing remains a key challenge. Here, we demonstrate that dimers of CdSe QDs, stable in solution, can be obtained by engineering QD surface chemistry, reducing the surface steric hindrance and favoring the link between two QDs. The connection is made by using alkyl dithiols as bifunctional linkers and different chain lengths are used to tune the interparticle distance from few nm down to 0.5 nm. The spectroscopic investigation highlights that coupling phenomena between the QDs in dimers are strongly dependent on the interparticle distance and QD size, ultimately affecting the exciton dissociation efficiency.

In recent years, the progress toward lighting miniaturization is focused on luminescent nanomaterials. Among them, fluorescent carbon dots (CDs) are receiving increasing attention thanks to their astonishing optical properties complemented by their intrinsic biocompatibility and low toxicity. The CDs can be easily dispersed in water, organic solvents or incorporated in polymeric matrices, preserving their emission properties. However, the relationship between their structural and optical properties is still not fully elucidated, motivating a consistent research effort for the comprehension of their features. Nevertheless, CDs demonstrate to be efficient gain materials for lasing, thanks to their high quantum yield (QY), emission tunability in the visible and near infrared (NIR) range, short lifetimes, and high absorption cross section, even if the synthetic reproducibility, the low reaction yield and the spectral width of the emission may limit their effective exploitation. This review summarizes the latest advancements in the investigation of the characteristic properties of CDs that make laser action possible, illustrating optical geometries for lasing and random lasing, both in solution and solid state, and the few currently demonstrated breakthroughs. While the journey toward their effective application is still long, the potential of CD‐based laser sources is promising in various technological fields and futuristic perspectives will be discussed.