Search Results (2)

Currently, the electrochemical reduction of carbon dioxide faces significant challenges, including poor selectivity for C₂ products and low conversion efficiency. An effective strategy for optimizing the reduction reaction pathway and enhancing catalytic performance involves manipulating highly unsaturated atomic sites on the catalyst’s surface, thereby increasing the number of active sites. In this study, we employed sodium dodecylbenzenesulfonate (SDBS) as a surfactant in the electrodeposition method to synthesize copper cubes encapsulated with an amorphous shell (100 nm–250 nm) containing numerous defect sites on its surface. The electrocatalytic CO₂ reduction reactions in an H-type reactor showed that, compared to ED-Cu synthesized without additives, AS (amorphous shell)-Cu-5 exhibited a Faradaic efficiency value for ethylene that was 1.7 times greater than that of ED-Cu while significantly decreasing the Faradaic efficiency of hydrogen production. In situ attenuated total reflectance surface-enhanced infrared spectroscopy (ATR-SEIRAS) revealed that introducing an amorphous shell and abundant defects altered both the intermediate species and reaction pathways on the AS-Cu-5 catalyst’s surface, favoring C₂H₄ formation. The density functional theory (DFT) calculations further confirmed that amorphous copper lowers the energy barrier required for C-C coupling, resulting in a marked enhancement in FE-C₂H₄. Therefore, additive-assisted electrodeposition presents a simple and rapid synthesis method for improving ethylene selectivity in copper catalysts. Full article

This paper investigates the effect of equivalence ratio on pollutant formation characteristics of CH₄O/H₂/NH₃ ternary fuel combustion and analyzes the pollutant formation mechanisms of CO, CO₂, and NO_X at the molecular level. It was found that lowering the equivalence ratio accelerates the decomposition of CH₄O, H₂, and NH₃ in general. The fastest rate of consumption of each fuel was found at φ = 0.33, while the rates of CH₄O and NH₃ decomposition were similar for the φ = 0.66 and φ = 0.4. CO shows an inverted U-shaped trend with time, and peaks at φ = 0.5. The rate and amount of CO₂ formation are inversely proportional to the equivalence ratio. The effect of equivalence ratio on CO₂ is obvious when φ > 0.5. NO₂ is the main component of NO_X. When φ < 0.66, NO_X shows a continuous increasing trend, while when φ ≥ 0.66, NO_X shows an increasing and then stabilizing trend. Reaction path analysis showed that intermediates such as CH₃ and CH₄ were added to the CH₄O to CH₂O conversion stage as the equivalence ratio decreased with φ ≥ 0.5. New pathways, CH₄O→CH₃→CH₂O and CH₄O→CH₃→CH₄→CH₂O, were added. At φ ≤ 0.5, new intermediates CHO₂ and CH₂O₂ were added to the CH₂O to CO₂ conversion stage, and new pathways are added: CH₂O→CO→CHO₂→CO₂, CH₂O→CO→CO₂, CH₂O→CHO→CO→CHO₂→CO₂, and CH₂O→CH₂O₂→CO₂. The reduction in the number of radical reactions required for the conversion of NH₃ to NO from five to two directly contributes to the large amount of NO_X formation. Equivalent ratios from 1 to 0.33 corresponded to 12%, 21.4%, 34%, 46.95%, and 48.86% of NO₂ remaining, respectively. This is due to the fact that as the equivalence ratio decreases, more O₂ collides to form OH and some of the O₂ is directly involved in the reaction forming NO₂. Full article