Pd Nanoparticles Loaded on Ceramic Membranes by Atomic Layer Deposition with Enhanced Catalytic Properties

Abstract

Atomic layer deposition (ALD) was adopted for the first time to load Pd nanoparticles on Al2O3 ceramic membranes (CMs) for fabricating catalytic membranes (Pd/CMs). The membrane surface was functionalized with the deposition of TiO2 by ALD and subsequent calcination under different atmospheres [CM-TiO2-A, obtained by calcination under an atmosphere of pure argon; CM-TiO2-H, obtained by calcination under a mixed atmosphere of H2 and Ar (H2/Ar = 1:9 in volume)]. The influence of the TiO2 deposition on the microstructure of catalytic membranes and their catalytic performance in p-nitrophenol reduction to p-aminophenol were investigated in detail. The catalytic activity of Pd/CM-TiO2-H improved by 1.9 times compared to Pd/CM, and 100% conversion of p-nitrophenol to p-aminophenol can be achieved. The X-ray photoelectron spectroscopy (XPS), inductively coupled plasma emission spectroscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy results indicate that the ALD of TiO2 and subsequent calcination under a 10% H2 atmosphere can produce more surface oxygen vacancies, providing more active sites for Pd­(hfac)2 adsorption and then promoting the loading of Pd nanoparticles. The XPS and H2 temperature-programmed reduction results suggest that calcining TiO2 under the 10% H2 atmosphere is more beneficial for the removal of the hfac ligands and the reduction of Pd­(hfac)2, leading to a higher Pd0 ratio. These two aspects contribute to the superior catalytic activity of Pd/CM-TiO2-H.

Keys Unlocking Redispersion of Reactive PdOx Nanoclusters on Ce-Functionalized Perovskite Oxides for Methane Activation

“…A Pd 3d 3/2 binding energy peak at ∼336.7 eV is observed in both Pd/LFO 3 and Pd/LCFO 3 , corresponding to the Pd 2+ species in PdO on the surface of the perovskite (Figure a). Pd 0 species (335.1 eV) are clearly present in the Pd/LFO 3 -N 2 and Pd/LCFO 3 -N 2 catalysts after N 2 treatment, suggesting that the oxide is nearly completely transformed to metal. Due to the phase change from oxide to metal, the redispersion process may result in a change in oxygen stoichiometry, which must be monitored.…”

Porous Membrane Reactors for Liquid-Phase Heterogeneous Catalysis

“…More importantly, this catalytic membrane reactor system could operate continuously and stably for more than 240 min. Lu et al adopted the atomic layer deposition (ALD) to load Pd nanoparticles on Al 2 O 3 ceramic membranes for fabricating catalytic membranes. The membrane surface was functionalized with the deposition of TiO 2 by ALD and subsequent calcination under different atmospheres.…”

Facile synthesis of an α-Bi2O3/BiO2 heterojunction for enhanced piezoelectric catalytic degradation of dye wastewater

“…This result has been confirmed by studies such as (Bi 1/2 Na 1/2 ) (1− x ) Ba x TiO 3 , 32 (Na 0.8 K 0.2 ) 0.5 Bi 0.5 TiO 3 , 33 and 0.51Pb(Hf 0.35 Ti 0.65 )O 3 –0.49Pb(Nb 2/3 Ni 1/3 )O 3 . 34 The deposition of metal cocatalysts such as Pt, 35 Pd, 36 Ag 37 and Co 38 on the semiconductor surface can enhance the effect of catalytic degradation. 39 By constructing a heterojunction, the position of the energy band structure can be adjusted, the separation efficiency of electrons and holes can be enhanced, and the catalyst performance can be improved, 40 such as Bi 2 O 3 /Bi 2 SiO 5 , 41 CdS/In 2 S 3 , 42 and MoS 2 /SrTiO 3 .…”