Noble metal

About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.

Confined Ultrathin Pd‐Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion

Abstract: An efficient strategy (enhanced metal oxide interaction and core-shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd-CeOx nanowire (2.4 nm) catalysts for methane combustion, which enable CH4 total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al2 O3 catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO2 ), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO2 . Pd-CeOx solid solution nanowires (Pd-Ce NW) as cores and porous silica as shells (Pd-CeNW@SiO2 ) were rationally prepared by a facile and direct self-assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water-gas shift reaction).

Dynamic active sites over binary oxide catalysts: In situ/operando spectroscopic study of low-temperature CO oxidation over MnOx-CeO2 catalysts

Abstract: The determination of the dynamic active sites over binary oxide catalysts is of great challenge in heterogeneous catalysis. In this work, the origin of active sites toward low-temperature CO oxidation ( x -CeO 2 composite oxide catalysts with different Mn/Ce molar ratios, synthesized by a redox co-precipitation method. The optimum Mn 1 Ce 1 catalyst (T 100 = 190 °C), which showed excellent activity, has found to be composed of three phases: (1) CeO 2 ; (2) amorphous MnO x ; (3) MnO x -CeO 2 solid solution (active sites). With the combination of kinetics and characterization results, including Temperature-Programmed-Desorption/Reduction (TPD/TPR), operando Raman spectroscopy and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS), the dynamic structures of catalysts were rationalized with the identification of the interface of MnO x and CeO 2 . The mechanism for CO oxidation over MnO x -CeO 2 in the temperature range 100–190 °C were proposed that the direct and the formate routes were followed at T 130 °C. Notably, the Mars-van Krevelen mechanism was proceeded in the whole temperature range. We speculate that cheap binary oxides will substitute for noble metal as catalysts for the removal of CO and other toxic gases, especially operating under mild conditions.

Thermolysis of Noble Metal Nanoparticles into Electron‐Rich Phosphorus‐Coordinated Noble Metal Single Atoms at Low Temperature

Abstract: Noble metal single atoms coordinated with highly electronegative atoms, especially N and O, often suffer from an electron-deficient state or poor stability, greatly limiting their wide application in the field of catalysis. Herein we demonstrate a new PH3 -promoted strategy for the effective transformation of noble metal nanoparticles (MNPs, M=Ru, Rh, Pd) at a low temperature (400 °C) into a class of thermally stabilized phosphorus-coordinated metal single atoms (MPSAs) on g-C3 N4 nanosheets via the strong Lewis acid-base interaction between PH3 and the noble metal. Experimental work along with theoretical simulations confirm that the obtained Pd single atoms supported on g-C3 N4 nanosheets exist in the form of PdP2 with a novel electron-rich feature, conceptionally different from the well-known single atoms with an electron-deficient state. As a result of this new electronic property, PdP2 -loaded g-C3 N4 nanosheets exhibit 4 times higher photocatalytic H2 production activity than the state-of-art N-coordinated PdSAs supported on g-C3 N4 nanosheets. This enhanced photocatalytic activity of phosphorus-coordinated metal single atoms with an electron-rich state was quite general, and also observed for other active noble metal single atom catalysts, such as Ru and Rh.