The polyol synthesis of nanoparticles is reviewed, including metals, oxides, main-group elements and recent strategies to expand the method's limits.

C-dots (3-5 nm in diameter) obtained by most simple heating of polyols (glycerol, diethylene glycol and PEG 400) show intense blue and green emission (50% quantum yield). Upon modification with TbCl3/EuCl3, energy transfer from the C-dots to the rare-earth metal results in line-type Tb(3+) (green)/Eu(3+) (red) emission with quantum yields up to 85%.

Synthesis of nanoparticles in high‐boiling alcohols (so‐called polyol synthesis) and surface functionalization of nanoparticles with polyethylene glycol (so‐called PEGylation) in combination with certain heating are often accompanied with an intense fluorescence in the blue to green spectral range. Based on the polyol synthesis of Zn3(PO4)2 nanoparticles and a critical consideration of the relevant experimental conditions—including the presence of nanoparticles, the role of dissolved metal salts (ZnCl2, MgCl2, KCl), the type of the polyol (DEG, GLY, PEG400), the temperature and time of heating (150–230 °C, 1–6 h)—we can correlate the observed fluorescence to the formation of carbon dots (C‐dots) stemming from thermal decomposition (i.e., dehydration and carbonization) of the polyol. Thus, the thermal decomposition of polyols results in C‐dots with a diameter of 3–5 nm at narrow size distribution. The formation of C‐dots is confirmed by transmission electron microscopy (TEM), high‐resolution TEM (HRTEM), X‐ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), and fluorescence spectra.

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Eu3+-modified carbon dots (C-dots), 3–5 nm in diameter, were prepared, functionalized, and stabilized via a one-pot polyol synthesis. The role of Eu2+/Eu3+, the influence of O2 (oxidation) and H2O (hydrolysis), as well as the impact of the heating procedure (conventional resistance heating and microwave (MW) heating) were explored. With the reducing conditions of the polyol at the elevated temperature of synthesis (200–230 °C), first of all, Eu2+ was obtained resulting in the blue emission of the C-dots. Subsequent to O2-driven oxidation, Eu3+-modified, red-emitting C-dots were realized. However, the Eu3+ emission is rapidly quenched by water for C-dots prepared via conventional resistance heating. In contrast to the hydroxyl functionalization of conventionally-heated C-dots, MW-heating results in a carboxylate functionalization of the C-dots. Carboxylate-coordinated Eu3+, however, turned out as highly stable even in water. Based on this fundamental understanding of synthesis and material, in sum, a one-pot polyol approach is established that results in H2O-dispersable C-dots with intense red Eu3+-line-type emission.

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Tellurium nanorods with a diameter of 10–20 nm and a length of 30–60 nm are prepared via hydrazine‐driven reduction of telluric acid. The size of the nanorods is controlled by the experimental conditions, including the N2H4·H2O–to–H2TeO4·2H2O ratio and the addition of polyvinylpyrrolidone (PVP). Although obtained at 0 °C, the as‐prepared tellurium nanorods are readily crystalline. For low aspect ratios (<5), the colloid and shape stability of the nanoparticles turned out as low; they show rapid agglomeration and merging due to storage and/or due to gentle heating (e.g., stirring, centrifugation). To increase the colloid and shape stability, a thin capping of Bi2Te3 is therefore established after the synthesis by addition of Bi(C6H5)3. As a result, Te@Bi2Te3 core@shell nanorods are obtained, exhibiting a Bi2Te3 capping layer of 6 nm in thickness. Composition and structure are validated by low‐energy STEM, HRTEM, HAADF‐STEM, XRD, FT‐IR, and line‐scan EDXS. The shape‐stabilized Bi2Te3‐capped tellurium nanorods can become an interesting precursor for Bi‐Te‐based thin‐film solar cells, thermoelectrics, or topological insulators.