The artificial photosynthesis of hydrogen peroxide (H₂O₂) is of great interest, yet simultaneously boosting the oxygen reduction reaction (ORR) while maintaining an efficient water oxidation reaction (WOR) poses a significant challenge. Herein, we present an innovative strategy to construct precisely engineered photocatalysts with adjacent dual active sites, which effectively promote both the ORR and WOR. Specifically, isolated tungsten (W) atoms are strategically positioned next to the triazine rings of polymeric carbon nitride, creating synergistic reactive regions with complementary ORR and WOR activities. Through a combination of experimental investigations and theoretical simulations, we demonstrate that by tuning the isolated W species, the adjacent coordinating triazine units can activate a highly selective two-electron ORR pathway, facilitating the production of H₂O₂. Simultaneously, the WOR occurs at the dedicated W site, and the in situ generated O₂ is rapidly consumed by the adjacent ORR active sites. This interplay between the two active sites is crucial for improving the overall reaction kinetics. The optimized catalyst exhibits exceptional performance, with a high activity of 556 μmol g⁻¹ h⁻¹ for overall H₂O₂ production with an apparent quantum yield of 8.53% and a remarkable solar-to-chemical conversion efficiency of 0.31%, outperforming most previously reported catalysts under similar conditions. The promising efficiency in H₂O₂ generation, accomplished through the intricate design of catalysts with cooperative dual sites, broadens the avenue for converting solar energy into valuable chemical products in a sustainable and environmentally friendly manner.

The nature and evolution of the hydrocarbon pool (HP) species during the Methanol-to-Olefins (MTO) process for three small-pore zeolite catalysts, with a different framework consisting of large cages interconnected by small eight-ring windows (CHA, DDR, and LEV) was studied at reaction temperatures between 350 and 450 °C using a combination of operando UV–vis spectroscopy and online gas chromatography. It was found that small differences in cage size, shape, and pore structure of the zeolite frameworks result in the generation of different hydrocarbon pool species. More specifically, it was found that the large cage of CHA results in the formation of a wide variety of hydrocarbon pool species, mostly alkylated benzenes and naphthalenes. In the DDR cage, 1-methylnaphthalene is preferentially formed, while the small LEV cage generally contains fewer hydrocarbon pool species. The nature and evolution of these hydrocarbon pool species was linked with the stage of the reaction using a multivariate analysis of the operando UV–vis spectra. In the 3-D pore network of CHA, the reaction temperature has only a minor effect on the performance of the MTO catalyst. However, for the 2-D pore networks of DDR and LEV, an increase in the applied reaction temperature resulted in a dramatic increase in catalytic activity. For all zeolites in this study, the role of the hydrocarbon species changes with reaction temperature. This effect is most clear in DDR, in which diamantane and 1-methylnaphthalene are deactivating species at a reaction temperature of 350 °C, whereas at higher temperatures diamantane formation is not observed and 1-methylnaphthalene is an active species. This results in a different amount and nature of coke species in the deactivated catalyst, depending on zeolite framework and reaction temperature.

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.