Heterogeneous molecular catalysts built from β-substituted cobalt porphyrins and carbon nanotubes afford tunable activity for H ₂ O ₂ synthesis via the two-electron transfer oxygen reduction reaction.

Sulfur-containing iron materials such as sulfidized nanoscale zerovalent iron (SNZVI) have shown outstanding water remediation performance in many recent studies, which is largely attributed to its high hydrophobicity compared to that of NZVI. However, the role of sulfur in the reactions, and the origin of the hydrophobicity of SNZVI, were still unclear. In this paper, for the first time, we conducted ab initio molecular dynamics simulation using an explicitly solvated model on both Fe and S-containing Fe surfaces, to explore the hydrophobicity of S-containing Fe materials. We found that the high hydrophobicity of these S-containing Fe surfaces originates from the hydrophobic nature of S: both doping S on top of the Fe surface and inserting S onto an Fe surface can significantly improve the surface hydrophobicity by increasing the distance between the water layer and the Fe surface. This exposes empty Fe sites which do not interact with water and in turn reduces hydrogen evolution. To compare with the theoretical analysis, we experimentally analyzed the hydrophobicity of both NZVI and SNZVI surfaces, leading to a good agreement with our theoretical analysis. We then theoretically show that the doping of other p-block elements (e.g., N and P) to iron surfaces can also create a hydrophobic phenomenon. Most importantly, this study points out that the potential contribution of hydrophobicity to the reactivity on liquid-phase reaction materials should not be ignored in the mechanistic analysis.

In this review, the synthesis methods of single-atom catalysts (SACs), and the mechanisms of SACs for CO₂electrochemical reduction, photocatalytic reduction, and thermo-catalytic reduction were thoroughly summarized.

For human safety, efficient removal of formaldehyde in indoor environments is essential. However, removing formaldehyde from indoor environments given the low-temperature and moisture content remains a challenge. In this study, a metal–organic framework-based single-atom iron catalyst (Fe_SA) is proposed as a candidate catalyst for formaldehyde oxidation. The adsorption characteristic and the reaction path over Fe_SA with different coordination environments were explored using density functional theory (DFT) calculation. Guided by the theoretical results, Fe_SA with 5-nitrogen coordination (Fe_SA–N₅–C) was selected and prepared for activity testing. The activity tests revealed that the removal efficiency of formaldehyde reached 85.8% at 25 °C and 75% relative humidity, which is far higher than currently reported data. More importantly, moisture can boost catalytic oxidation of formaldehyde through reduction of the energy barrier and activation of the O₂ molecule, illustrating that Fe_SA–N₅–C is robust enough for practical applications. We propose a new catalyst design route for removing formaldehyde from indoor environments, aiming for high low-temperature activity, strong water-resistance, and long-term stability.