Two-Step Carbothermal Welding To Access Atomically Dispersed Pd₁ on Three-Dimensional Zirconia Nanonet for Direct Indole Synthesis

Abstract

Herein, we report a novel carbothermal welding strategy to prepare atomically dispersed Pd sites anchored on a three-dimensional (3D) ZrO2 nanonet (Pd1@ZrO2) via two-step pyrolysis, which were evolved from isolated Pd sites anchored on linker-derived nitrogen-doped carbon (Pd1@NC/ZrO2). First, the NH2–H2BDC linkers and Zr6-based [Zr6(μ3-O)4(μ3-OH)4]12+ nodes of UiO-66-NH2 were transformed into amorphous N-doped carbon skeletons (NC) and ZrO2 nanoclusters under an argon atmosphere, respectively. The NC supports can simultaneously reduce and anchor the Pd sites, forming isolated Pd1–N/C sites. Then, switching the argon to air, the carbonaceous skeletons are gasified and the ZrO2 nanoclusters are welded into a rigid and porous nanonet. Moreover, the reductive carbon will result in abundant oxygen (O*) defects, which could help to capture the migratory Pd1 species, leaving a sintering-resistant Pd1@ZrO2 catalyst via atom trapping. This Pd1@ZrO2 nanonet can act as a semi-homogeneous catalyst to boost the direct synthesis of indole through hydrogenation and intramolecular condensation processes, with an excellent turnover frequency (1109.2 h–1) and 94% selectivity.

A Supported Nickel Catalyst Stabilized by a Surface Digging Effect for Efficient Methane Oxidation

“…By continuously elevating the annealing temperature to 900 °C, the sunk Ni NPs could be converted in situ into Ni SAs through a thermal atomization within the surface holes (Supporting Information, Figure S13–S16). Thermogravimetric analysis (TGA) was used to track the weight loss throughout the whole evolution process, during which thermal degradation of linkers started over 200 °C (Supporting Information, Figure S18) . TEM and HAADF images show the presence of pores and the absence of Ni NPs, demonstrating the digging effect and transformation from Ni NPs to Ni SAs (Figure e,f).…”

Designing Atomic Active Centers for Hydrogen Evolution Electrocatalysts

“…[59][60][61] 100 %atom utilization efficiency,unique structures,e xceptional catalytic properties,a nd convenient separation process are realized. [62][63][64] Furthermore,o ther catalysts with atomic active centers (single-atom alloys,c atalysts with dual sites,e tc.) show high HER activity [65][66][67] and offer an alternative to platinum SACs.F igure 1g ives an up-to-date summary of the atomic active centers reported as well as the existing synthetic methods.…”

Design aktiver atomarer Zentren für HER‐Elektrokatalysatoren

“…Aus dem Inhalt prozess gewährleistet. [62][63][64] Auch andere Katalysatoren mit aktiven atomaren Zentren (Einzelatomlegierungen,Z wei-Zentren-Katalysatoren usw.) weisen eine hohe HER-Aktivitätauf [65][66][67] und bieten somit eine Alternative zu Platin-SACs.…”

“…SACs erreichen eine gleichmäßige Dispersion und Verankerung der Metallatome, wobei sie die Vorzüge von Heterogen‐ und Homogenkatalysatoren vereinen [59–61] . So werden eine 100‐prozentige Atomökonomie, die Bildung einzigartiger Strukturen, außergewöhnliche katalytische Eigenschaften und ein bequemer Reinigungsprozess gewährleistet [62–64] . Auch andere Katalysatoren mit aktiven atomaren Zentren (Einzelatomlegierungen, Zwei‐Zentren‐Katalysatoren usw.)…”