In this review, we highlight recent advancements in 3D graphene foam synthesis by template-assisted chemical vapor deposition, as well as their potential energy storage and conversion applications. This method offers good control of the number of graphene layers and porosity, as well as continuous connection of the graphene sheets. The review covers all the substrate types, catalysts, and precursors used to synthesize 3D graphene by the CVD method, as well as their most viable energy-related applications.

The unique photoluminescent properties of carbon dots (CDs) continue to encourage a great interest in their development for a wide range of applications in energy conversion, optoelectronics or sensing. Engaging carbon dots in resonance energy transfer processes with organic dyes could enable the design of functional materials to greatly enhance the performance of solar cells and other optoelectronic devices, or to create new types of sensors. In this work, CDs were functionalized with Rhodamine B (RhB) isothiocyanate, (CD–PEG_1500N–Rh) via a simple procedure after surface modification of bare carbon nanoparticles with poly(ethylene glycol) bis(3-aminopropyl) (PEG_1500N). The morphology of CD–PEG_1500N was ascertained using HR-TEM while the covalent linkage of Rhodamine B at the surface of PEG_1500N capped CDs was proved by spectroscopic analysis. The overlap between the emission spectra of CDs and the absorption spectrum of RhB molecules favoured fluorescent (Förster) resonance energy transfer (FRET) from the CDs to the dye molecules. The FRET mechanism was firstly demonstrated by steady-state fluorescence measurements and its efficiency was estimated by photoluminescence lifetime measurements, using the time correlated single photon counting (TCSPC) method with the excitation of picosecond pulse lasers. The synthetic accessibility and the transfer efficiency of these conjugates make them reliable candidates for fluorescent materials to be later used in FRET based sensing platforms and photovoltaic devices.

The versatility of the surface chemistry of carbon dots (CDs) can generate high flexibility in engineering their surface functionality for a wide and precise array of applications. In respect of this, we perform for the first time the surface passivation of carboxylated carbon nanoparticles with p-phenylenediamine to prepare water soluble photoluminescent CDs exhibiting intriguing physicochemical properties. The new strategy used to engineer the surface functionality allows us to synthesize CDs with a stable excitation independent green photoluminescence with a quantum yield of 14% and lifetime of 11.8 ns, suitable for application in bioimaging, sensing and optoelectronics.

Polymeric nanocomposite materials that are highly thermally conductive are important to a variety of applications, with examples ranging from flexible radiators in space to high-performance aircrafts and vehicles and to cutting-edge electronics. Among widely used nanoscale fillers in the development of these materials are carbon nanotubes and graphene sheets. As concluded in previous reviews, the performance of carbon nanotubes for imparting high thermal conductivity into polymeric matrices was generally poor. Here recent results associated with the effort on significant performance improvements are reviewed as an update. By contrast, graphene sheets have emerged as effective nanoscale fillers for polymeric nanocomposites of excellent thermal transport performance, reaching levels that are competitive to those achieved by metals. The significant recent results on thermally conductive polymeric nanocomposites with graphene sheets are highlighted, and their potential applications and issues on their further performance improvements are discussed.

We unveiled the effect of doping on the morpho-structural and opto/electrical properties of Ca-doped ZnO:Al thin films obtained by RF magnetron sputtering. Scanning electron microscopy (SEM) was performed to reveal the surface morphology, while the composition and crystal structure were investigated by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The correlation between the microstructure and the electrical conductivity identifies an increase in electrical conductivity up to 145 × 10⁻³ Ω⁻¹·m⁻¹ at 5 wt.% Ca doping level with the decrease in the grain size. Furthermore, the presence of Ca dopant triggers the occurrence of the emission peak at 430 nm and an increase of the green emission peak in PL spectra. Corroborating the electrical measurements with X-ray diffraction and optical measurements, one can infer that the electrical conductivity is dominated by intrinsic defects developed during deposition and by the existence of dopants.