No abstract

Single atom CoN -C can be used as a low-cost cathode catalyst for Li-O 2 batteries (LOBs) with abundant highly active sites and high efficient atom utilizations. In the present work, hierarchical porous single atom CoN -C catalyst was prepared through acid etching from a Co/Co-N-C intermediate, featuring an efficient slack of volume expansion, easy mass transmission via the interconnected carbon-framework, and sufficient surface area to accommodate discharge products. The single atom CoN -C catalyst exhibited a superior catalytic capacity for LOBs with a large specific capacity of 14075 mAh g-1 and a long cycle life of 340 cycles. The oxygen reduction reaction (ORR) / oxygen evolution reaction (OER) mechanisms of the discharge products of single atom CoN -C catalyst were identified by using density functional theory (DFT) calculations, showing avenues for improving the future design of single atom catalyst.

Amplification of the intensity and dissymmetry factors (glum) of circularly polarized light is desired to broaden the range of applications of circularly polarized luminescence (CPL) because of the small glum values commonly observed for CPL materials and the loss of intensity resulting from circular polarization. In this study, enhanced CPL produced by metal‐enhanced fluorescence is successfully achieved by the self‐assembly of Au@SiO2 triangular nanoprisms (Au@SiO2TNPs) and fluorophores (sulforhodamine 101 and methylene blue) in chiral cellulose nanocrystal films. By overlapping the plasmon bands of Au@SiO2TNPs and the excitation–emission spectra of fluorophores, both the fluorescence intensity and glum value of CPL are significantly enhanced. For sulforhodamine 101 in the metal‐enhanced CPL system, a 52‐fold fluorescence enhancement is achieved, and the glum value increased from −0.038 to −0.126. For methylene blue in the metal‐enhanced CPL system, a 201‐fold enhancement of fluorescence is obtained, and the glum value is enhanced from −0.055 to −0.085. This metal‐enhanced CPL film is expected to generate superior circularly polarized light for extensive CPL applications because of its outstanding enhanced CPL, fluorescence amplification, and feasibility for different fluorophores.

The surface conditions of MoSi2 particles and the stable crystal structure contribute to the great electrochemical performance of Li–O2 batteries.