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Non-precious metal catalysts with enhanced low-temperature activity and improved water resistance are highly demanded for emission control. CuO-based catalysts are promising alternatives to precious metal catalysts due to their acceptable activity and cost-effectiveness. However, there is an urgent need to further enhance their low-temperature activity and water resistance for industrial applications. Herein, CuO catalysts supported by various SiO2-TiO2 supports were prepared and evaluated for CO oxidation and NO reduction by CO reactions under the testing conditions with and without water. Among the studied catalysts with different SiO2 contents, CuO/5SiO2-TiO2, in which CuO was supported by SiO2-TiO2 with 5 wt.% SiO2, exhibited the best performance for CO oxidation. Compared with CuO/TiO2 and CuO/SiO2 reference catalysts, the CuO/5SiO2-TiO2 catalyst showed enhanced catalytic activity in both CO oxidation and NO reduction by CO under dry and wet conditions. Comprehensive characterizations revealed that the presence of SiO2 in TiO2 support facilitated the CuO/5SiO2-TiO2 catalyst with a high dispersion and reduced oxidation states of CuOx species. This not only improved the low-temperature reducibility but also enhanced the adsorption of reactive CO species. As a result, the CuO/5SiO2-TiO2 catalyst demonstrated superior catalytic activity. Furthermore, the inclusion of SiO2 in the catalyst inhibited H2O adsorption, contributing to the enhanced water resistance on CuO/5SiO2-TiO2 catalyst. These advantages in catalytic activity and water resistance make CuO/5SiO2-TiO2 a promising candidate for applications in emission control. [ABSTRACT FROM AUTHOR]

Non-precious metal catalysts with enhanced low-temperature activity and improved water resistance are highly demanded for emission control. CuO-based catalysts are promising alternatives to precious metal catalysts due to their acceptable activity and cost-effectiveness. However, there is an urgent need to further enhance their low-temperature activity and water resistance for industrial applications. Herein, CuO catalysts supported by various SiO2-TiO2 supports were prepared and evaluated for CO oxidation and NO reduction by CO reactions under the testing conditions with and without water. Among the studied catalysts with different SiO2 contents, CuO/5SiO2-TiO2, in which CuO was supported by SiO2-TiO2 with 5 wt.% SiO2, exhibited the best performance for CO oxidation. Compared with CuO/TiO2 and CuO/SiO2 reference catalysts, the CuO/5SiO2-TiO2 catalyst showed enhanced catalytic activity in both CO oxidation and NO reduction by CO under dry and wet conditions. Comprehensive characterizations revealed that the presence of SiO2 in TiO2 support facilitated the CuO/5SiO2-TiO2 catalyst with a high dispersion and reduced oxidation states of CuOx species. This not only improved the low-temperature reducibility but also enhanced the adsorption of reactive CO species. As a result, the CuO/5SiO2-TiO2 catalyst demonstrated superior catalytic activity. Furthermore, the inclusion of SiO2 in the catalyst inhibited H2O adsorption, contributing to the enhanced water resistance on CuO/5SiO2-TiO2 catalyst. These advantages in catalytic activity and water resistance make CuO/5SiO2-TiO2 a promising candidate for applications in emission control. [ABSTRACT FROM AUTHOR]

Low-loading Pd supported on Fe 2 O 3 nanoparticles was synthesized. A common nanocatalyst system with previously reported synergistic enhancement of reactivity that is attributed to the electronic interactions between Pd and the Fe 2 O 3 support. Fe 2 O 3 -selective precoalescence overcoating with ZnO atomic layer deposition (ALD), using Zn(CH 2 CH 3 ) 2 and H 2 O as precursors, dampens competitive hydrogenation reactivity at Fe 2 O 3 -based sites. The result is enhanced efficiency at the low-loading but high reactivity Pd sites. While this increases catalyst efficiency toward most aqueous redox reactions tested, it suppresses reactivity toward polyaromatic core substrates. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) show minimal electronic impacts for the ZnO overcoat on the Pd particles, implying a predominantly physical site blocking effect as the reason for the modified reactivity. This serves as a proof-of-concept of not only stabilizing supported nanocatalysts but also altering reactivity with ultrathin ALD overcoats. The results point to a facile ALD route for selective enhancement of reactivity for low-loading Pd-based supported nanocatalysts.

The extremely poor solution stability and massive carrier recombination have seriously prevented III-V semiconductor nanomaterials from efficient and stable hydrogen production. In this work, an anodic reconstruction strategy based on group III-V active semiconductors is proposed for the first time, resulting in 19-times photo-gain. What matters most is that the device after anodic reconstruction shows very superior stability under the protracted photoelectrochemical (PEC) test over 8100 s, while the final photocurrent density does not decrease but rather increases by 63.15%. Using the experiment and DFT theoretical calculation, the anodic reconstruction mechanism is elucidated: through the oxidation of indium clusters and the migration of arsenic atoms, the reconstruction formed p + -GaAs/a-InAsN. The hole concentration of the former is increased by 10 times (5.64 × 10 18  cm -1 increases up to 5.95 × 10 19  cm -1 ) and the band gap of the latter one is reduced to a semi-metallic state, greatly strengthening the driving force of PEC water splitting. This work turns waste into treasure, transferring the solution instability into better efficiency., (© 2024 Wiley‐VCH GmbH.)

Fine-tuning the dispersion of active metal species on widely used supports is a research hotspot in the catalysis community, which is vital for achieving a balance between the atomic utilization efficiency and the intrinsic activity of active sites. In this work, using bayerite Al(OH) 3 as support directly or after precalcination at 200 or 550 °C, Pt/Al 2 O 3 catalysts with distinct Pt dispersions from single atoms to clusters ( ca . 2 nm) were prepared and evaluated for CO and NH 3 removal. Richer surface hydroxyl groups on AlO x (OH) y support were proved to better facilitate the dispersion of Pt. However, Pt/Al 2 O 3 with relatively lower Pt dispersion could exhibit better activity in CO/NH 3 oxidation reactions. Further reaction mechanism study revealed that the Pt sites on Pt/Al 2 O 3 with lower Pt dispersion could be activated to Pt 0 species much easier under the CO oxidation condition, on which a higher CO adsorption capacity and more efficient O 2 activation were achieved simultaneously. Compared to Pt single atoms, PtO x clusters could also better activate NH 3 into -NH 2 and -HNO species. The higher CO adsorption capacity and the more efficient NH 3 /O 2 activation ability on Pt/Al 2 O 3 with relatively lower Pt dispersion well explained its higher CO/NH 3 oxidation activity. This study emphasizes the importance of avoiding a singular pursuit of single-atom catalyst synthesis and instead focusing on achieving the most effective Pt species on Al 2 O 3 support for targeted reactions. This approach avoids unnecessary limitations and enables a more practical and efficient strategy for Pt catalyst fabrication in emission control applications.

Transition metal catalysts, such as copper oxide, are more attractive alternatives to noble metal catalysts for emission control due to their higher abundance, lower cost, and excellent catalytic activity. In this study, we report the preparation and application of a novel CuO/CeO 2 catalyst using a hydroxyl-rich Ce(OH) x support for CO oxidation and NO reduction by CO. Compared to the catalyst prepared from a regular CeO 2 support, the new CuO/CeO 2 catalyst prepared from the OH-rich Ce(OH) x (CuO/CeO 2 -OH) showed significantly higher catalytic activity under different testing conditions. The effect of OH species in the CeO 2 support on the catalytic performance and physicochemical properties of the CuO/CeO 2 catalyst was characterized in detail. It is demonstrated that the abundant OH species enhanced the CuO x dispersion on CeO 2 , increased the CuO x -CeO 2 interfaces and surface defects, promoted the oxygen activation and mobility, and boosted the NO adsorption and dissociation on CuO/CeO 2 -OH, thus contributing to its superior catalytic activity for both CO oxidation and NO reduction by CO. These results suggest that the OH-rich Ce(OH) x is a superior support for the preparation of highly efficient metal catalysts for different applications.