A decomposed copper based metal–organic framework containing amorphous Cu species was found to be a highly reactive carbon supported catalyst (a-Cu@C). This catalyst is active for reduction, oxidation, and N-arylation reactions without further tuning or optimization. Higher catalyst turnover numbers for each of these transformations are obtained when comparing a-Cu@C activity to similar Cu-based materials.

Discovery of new materials plays a critical role in developing advanced high-temperature thermoelectric (TE) applications. Transition metal oxides (TMOs) are one of the attractive candidates for high-temperature TE applications due to their thermal and chemical stability. However, the trade-off relationship between thermopower (S) and electrical conductivity (σ) limits the maximum attainable power factor (PF), thereby hindering improvements in TE conversion efficiency. To overcome this trade-off relationship, the emerging approach of the redox-driven metal exsolution in TMOs shows promise in improving both S and σ. However, the effect of metal exsolution with different particle sizes and densities on S and σ is still largely unexplored. This study demonstrates an unusually large enhancement in PF through the exsolution of Ni nanoparticles in epitaxial La_0.7Ca_0.2Ni_0.25Ti_0.75O₃ (LCNTO) thin films. Metal exsolution leads to a decrease in the carrier concentration while increasing the carrier mobility due to energy filtering effects. In addition, the exsolved metal particles introduce the high-mobility electron carriers into the low-mobility LCNTO matrix. Consequently, the exsolution of metal particles results in a significant enhancement in S along with a substantial increase in σ, compared to the pristine film. Overall, the TE power factor of LCNTO is dramatically enhanced by up to 8 orders of magnitude owing to the presence of exsolved metal particles. This enhancement is attributed to the selective filtering of carriers caused by energy band bending at the metal-oxide interfaces and the high-mobility carriers from the exsolved Ni particles with a high Ni⁰ fraction. This study unequivocally demonstrates the impact of metal exsolution on oxide TE properties and provides a novel route to tailor the interconnected physical and chemical properties of oxides, leading to enhanced thermoelectric power output.

Ammonia synthesis is one of the most important chemical reactions. Due to thermodynamic restrictions and the reaction requirements of the current commercial iron catalysts, it is also one of the worst reactions for carbon dioxide emissions and energy usage. Ruthenium-based catalysts can substantially improve the environmental impact as they operate at lower pressures and temperatures. In this work, we provide a screening of more than 40 metals as possible promoter options based on a Ru/Pr₂O₃ catalyst. Cesium was the best alkali promoter and was held constant for the series of double-promoted catalysts. Ten formulations outperformed the Ru-Cs/PrO_x benchmark, with barium being the best second promoter studied and the most cost-effective option. Designs of experiments were utilized to optimize both the pretreatment conditions and the promoter weight loadings of the doubly promoted catalyst. As a result, optimization led to a more than five-fold increase in activity compared to the unpromoted catalyst, therefore creating the possibility for low-ruthenium ammonia synthesis catalysts to be used at scale. Further, we have explored the roles of promoters using kinetic analysis, X-ray Photoelectron Spectroscopy (XPS), and in situ infrared spectroscopy. Here, we have shown that the role of barium is to act as a hydrogen scavenger and donor, which may permit new active sites for the catalyst, and have demonstrated that the associative reaction mechanism is likely used for the unpromoted Ru/PrO_x catalyst with hydrogenation of the triple bond of the dinitrogen occurring before any dinitrogen bond breakage.

Completely selective hydrodeoxygenation achieved using a hybrid molecular/heterogeneous catalyst.

Inorganic ultraviolet (UV) filters in mineral sunscreens (MSCs) are known to generate reactive oxygen species (ROS), including transient free radicals, under light exposure. Recent findings indicate that these filters (titanium dioxide [TiO₂] and zinc oxide [ZnO]) also assist in generating long-lived free radicals. The photochemical formation of these radicals during routine sunscreen use and as they enter the environment remains unknown, highlighting the need for studies to inform safer sunscreen formulation, reduce adverse health risks, and protect aquatic ecosystems. Here, we provide the first evidence that all commercial sunscreen formulations we used in this study generated substantial amounts of persistent free radicals (PFRs), which remain long after light exposure ends. Both MSCs and organic chemical sunscreens (OSCs) yielded PFRs, though MSCs generated higher levels overall. In most formulations, water exposure significantly reduced PFRs, except in MSC with ZnO-only content, where PFR yields increased. ZnO-only MSCs formed substantial levels of PFRs even when irradiated underwater, producing twice the radical signal observed under ambient air. Among OSCs, UV filters with phenolic groups produced more PFRs, though bulky substituents suppress their formation. Under typical application, we estimate 10¹⁷ PFRs may form. These results raise concerns about potential environmental and health risks associated with MSC use that persist beyond exposure and may lead to prolonged oxidative stress in human skin and aquatic environments.

The temperature stability window of mesoporous niobium tungstates is improved by 500 °C using pore backfilling strategies with carbon precursors.