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NiOx/CeO2catalysts have shown promising results in various catalytic reactions, including the NO reduction by CO. In this study, we investigated the effect of oxidation and reduction treatments on the NO reduction by CO over pretreated NiOx/CeO2catalysts. A series of oxidized and reduced supported NiOxcatalysts were synthesized in two steps: (1) the pretreatment of CeO2supports at different temperatures (400, 500, and 700 °C) under oxidizing and reducing conditions and (2) the synthesis of NiOx/CeO2catalysts by an incipient wetness impregnation method (IWI) with a fixed surface density of 5.3 Ni per nm2under specific conditions (oxidation/reduction) applied during the CeO2treatment. The prepared catalysts were characterized viaBET, ICP/OES, Raman, XPS, and XRD to understand their physicochemical properties. The results showed that as the pretreatment temperature increased, the physicochemical properties of NiOx/CeO2catalysts were changed: a decreased specific surface area (SSA), decreased oxygen vacancy/defect sites, and an increased crystallite size. The oxidized NiOx/CeO2catalyst at a lower pretreatment temperature displayed a better catalytic activity, indicating that the physicochemical properties of the catalysts were key factors in enhancing the catalytic activity. To understand the intermediate species and reaction mechanism during the NO reduction by CO, an in situDRIFTS study was performed and a possible reaction mechanism was also discussed.

The flammability of silicone rubber (SR) significantly limits its broad use in areas that require high flame retardancy. In this study, heptazine-covered Fe2O3, which exhibits effective flame retardancy, was prepared using simple ball milling and heat treatment, which are advantageous for large-scale production. The prepared filler was incorporated into SR. The addition of 7.02 wt% FM filler increased the thermal degradation onset temperature at 5 % weight loss from 492.5 °C for neat SR to 502.7 °C (FM 1:1 composite). Moreover, the peak heat release rate and peak smoke production rate of the FM 1:1 composite significantly decreased by 43.15 % and 68.42 %, respectively, indicating a significant enhancement in the fire safety and smoke suppression of the FM composites. The chemical, morphological, and electronic structures of the FM fillers, pyrolysis gas production, and char residue were thoroughly investigated to reveal the possible flame-retarding mechanisms of the SR composites.

Herein, bimetallic sulfide with sulfur vacancies and N, S co-doped reduced graphene oxide (Vs-CoxFe1-xS2/N,S-rGO) are synthesized and employed as bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media. Generation of sulfur vacancies into the bimetal sulfides not only modifies the electronic structure but enhances the surface charge and polarity, which is beneficial for the electrocatalytic performance in alkaline condition. Furthermore, homogeneously introduced heteroatom dopants in rGO provides numerous defect sites, leading to the effective adsorption of reactants for both ORR and OER. Based on the above features, the electrocatalyst exhibits exceptional performance with high half-wave potential and low overpotential for ORR and OER, respectively, outperforming precious metal-based catalysts. Also, the Vs-CoxFe1-xS2/N,S-rGO-based rechargeable Zn-air battery (ZAB) displayed outstanding battery performances with high specific capacity (754.8 mAh gZn−1) and superior long-term cyclability over 420 cycles. These findings highlight the Vs-CoxFe1-xS2/N,S-rGO catalyst as a promising candidate for high performance electrochemical energy conversion and storage devices.