Mn-based oxides are promising for the selective catalytic reduction (SCR) of NOx with NH₃ at temperatures below 200 °C. There is a general agreement that combining Mn with another metal oxide, such as CeOx improves catalytic activity. However, to date, there is an unsettling debate on the effect of Ce. To solve this, here we have systematically investigated a large number of catalysts. Our results show that, at low-temperature, the intrinsic SCR activity of the Mn active sites is not positively affected by Ce species in intimate contact. To confirm our findings, activities reported in literature were surface-area normalized and the analysis do not support an increase in activity by Ce addition. Therefore, we can unequivocally conclude that the beneficial effect of Ce is textural. Besides, addition of Ce suppresses second-step oxidation reactions and thus N₂O formation by structurally diluting MnOx. Therefore, Ce is still an interesting catalyst additive.

Platinum single atoms are grafted by SOMC on morphology-controlled TiO₂. Their structure is characterized by EXAFS and other techniques, and their activity and stability in HER and backwards reaction are studied and compared to Pt nanoparticles.

Dissolved MoO₄²⁻ from NiMo electrodes during hydrogen evolution redeposits during high energy spectroscopy, providing misleading but important insights into Mo behavior.

Significance: Platinum group elements (PGE) are highly valued by many industrial applications, serve as important geochemical tracers of planetary processes, and are among eagerly sought natural resources of critical trace metals. We show here that aqueous sulfur-bearing fluids play a far more important role than believed in many natural and technological processes in which PGE are involved. This role is essentially ensured by the radical sulfur ion S ₃ ^•− that forms extremely stable and soluble complexes with both Pt ^II and Pt ^IV . By enabling enhanced dissolution, transport, and precipitation of Pt, these species may be key players in PGE transfer, fractionation, and accumulation in the Earth’s crust. They may also offer novel opportunities for optimizing ore processing and nanomaterial synthesis.

The speciation of highly-diluted elements by X-ray absorption spectroscopy in a diverse range of materials is extremely challenging, especially in biological matrices such as articular cartilage. Here we show that using a high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) technique coupled to an array of crystal analyzers, selenium speciation down to 400 ppb (μg kg⁻¹) within articular cartilage can be demonstrated. This is a major advance in the speciation of highly-diluted elements through X-ray absorption spectroscopy and opens new possibilities to study the metabolic role of selenium and other elements in biological samples.