Atomically dispersed transition metal sites have been extensively studied for CO 2 electroreduction reaction (CO 2 RR) to CO due to their robust CO 2 activation ability. However, the strong hybridization between directionally localized d orbits and CO vastly limits CO desorption and thus the activities of atomically dispersed transition metal sites. In contrast, s-block metal sites possess nondirectionally delocalized 3s orbits and hence weak CO adsorption ability, providing a promising way to solve the suffered CO desorption issue. Herein, we constructed atomically dispersed magnesium atoms embedded in graphitic carbon nitride (Mg-C 3 N 4 ) through a facile heat treatment for CO 2 RR. Theoretical calculations show that the CO desorption on Mg sites is easier than that on Fe and Co sites. This theoretical prediction is demonstrated by experimental CO temperature program desorption and in situ attenuated total reflection infrared spectroscopy. As a result, Mg-C 3 N 4 exhibits a high turnover frequency of % 18 000 per hour in H-cell and a large current density of À300 mA cm À2 in flow cell, under a high CO Faradaic efficiency ! 90 % in KHCO 3 electrolyte. This work sheds a new light on s-block metal sites for efficient CO 2 RR to CO.

An eco‐friendly bio‐filler was prepared by reusing of chicken eggshell (CES), and well characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM)‐energy dispersive X‐ray spectroscopy (EDS), X‐ray fluorescence spectrometry (XRF), and thermo‐gravimetric (TG) analysis. The influence of CES on the thermal stability, flame‐retardant, and smoke suppression properties of epoxy‐based traditional intumescent system was investigated by limited oxygen index (LOI), UL 94 test, cone calorimeter test, and TG analysis. The results shows that the incorporation of CES improves the LOI value of the samples, and IFR‐3 with 37 wt% intumescent flame retardant (IFR) and 3 wt% CES exhibits the maximum LOI value of 31.5%. The results from cone calorimeter and smoke density tests reveal that the addition of CES greatly decreases the heat release and smoke production of the samples concomitant with an increase in the residual weight, which is ascribed to the formation of a more compact, thermally stable, and intumescent char against heat and mass transfer during burning. The synergistic effect on fire performance between CES and IFR depends on the content of CES, and an excessive content of CES diminishes this synergistic effect. The TG analysis shows that the intumescent system containing CES exhibits high thermal stability and char‐forming ability. Overall, CES can serve as an environmentally friendly bio‐filler and a promising synergist for intumescent systems. POLYM. COMPOS., 40:2712–2723, 2019. © 2018 Society of Plastics Engineers

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