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High-quality CdS, ZnS and alloyed Zn x Cd 1 2 x S nanocrystals are synthesized in the commonly available coordinating solvent, high boiling-point long-chain amines, using the corresponding metal salts (such as metal stearate, acetate, chloride, sulfate etc.) and elemental sulfur as the precursors. The obtained CdS and alloyed Zn x Cd 1 2 x S nanocrystals possess quantum-confinement wavelength-tunable optical absorption and band-edge emission with photoluminescence quantum yields of 25-45%. The photoluminescence spectra are dominated by the band-edge emission without deep-trap emission. Particular interests in this synthetic approach are that cubic zinc-blende CdS and Zn x Cd 1 2 x S nanocrystals are formed at high temperatures, and the rapid nucleation and instant termination of the crystal growth process is observed. This nucleation and growth feature makes the reproducible and controllable synthesis of nanocrystals with specific emission wavelengths feasible. The alloy structure of the Zn x Cd 1 2 x S nanocrystals is proved by the optical spectra and XRD diffractograms, in which the absorption onset and emission peak shift to shorter wavelength; the diffraction peaks systematically shift toward larger angles with an increase of the Zn molar ratio in the material.

Most previous efforts are devoted to developing transition metals as electrocatalysts guided by the d‐band center model. The metals of the s‐block of the periodic table have so far received little attention in the application of oxygen reduction reactions (ORR). Herein, a carbon catalyst with calcium (Ca) single atom coordinated with N and O is reported, which displays exceptional ORR activities in both acidic condition (E1/2 = 0.77 V, 0.1 m HClO4) and alkaline condition (E1/2 = 0.90 V, 0.1 m KOH). The CaN, O/C exhibits remarkable performance in zinc–air battery with a maximum power density of 218 mW cm–2, superior to a series of catalysts reported so far. X‐ray absorption near‐edge structure (XANES) characterization confirms the formation of N‐ and O‐atom‐coordinated Ca in the carbon matrix. Density functional theory (DFT) calculations reveal that the high catalytic activity of main‐group Ca is ascribed to the fact that its p‐orbital electron structure is regulated by N and O coordination so that the highest peak (EP) of the projected density of states (PDOS) for the Ca atom is moved close to the Fermi level, thereby facilitating the adsorption of ORR intermediates and electron transfer.