Boron Nitride as a Novel Support for Highly Stable Palladium Nanocatalysts by Atomic Layer Deposition

Abstract

The ability to prepare controllable nanocatalysts is of great interest for many chemical industries. Atomic layer deposition (ALD) is a vapor phase technique enabling the synthesis of conformal thin films and nanoparticles (NPs) on high surface area supports and has become an attractive new route to tailor supported metallic NPs. Virtually all the studies reported, focused on Pd NPs deposited on carbon and oxide surfaces. It is, however, important to focus on emerging catalyst supports such as boron nitride materials, which apart from possessing high thermal and chemical stability, also hold great promises for nanocatalysis applications. Herein, the synthesis of Pd NPs on boron nitride (BN) film substrates is demonstrated entirely by ALD for the first time. X-ray photoelectron spectroscopy indicated that stoichiometric BN formed as the main phase, with a small amount of BNxOy, and that the Pd particles synthesized were metallic. Using extensive transmission electron microscopy analysis, we study the evolution of the highly dispersed NPs as a function of the number of ALD cycles, and the thermal stability of the ALD-prepared Pd/BN catalysts up to 750 °C. The growth and coalescence mechanisms observed are discussed and compared with Pd NPs grown on other surfaces. The results show that the nanostructures of the BN/Pd NPs were relatively stable up to 500 °C. Consequent merging has been observed when annealing the samples at 750 °C, as the NPs’ average diameter increased from 8.3 ± 1.2 nm to 31 ± 4 nm. The results presented open up exciting new opportunities in the field of catalysis.

Atomic Layer Deposition of Two-Dimensional Layered Materials: Processes, Growth Mechanisms, and Characteristics

“…In the first study, the ALD BN was deposited nearly stoichiometrically at both 400 C and 750 C. 50 X-ray diffraction (XRD) analyses revealed that the BN films were less ordered at 400 C but had improved crystallinity at 750 C, showing a turbostratic BN structure (t-BN). This BBr 3 /NH 3 process of ALD BN has been practiced on various substrates at 750 C. [52][53][54][55][56][57] Aimed at improving this ALD process at a lower temperature and with a higher growth rate, a subsequent study used a laser to assist the ALD in a wider range of 250 C-750 C. 51 The laser helped create more reactive fragments, and this laser-assisted ALD (LALD) process resulted in higher growth per cycle (GPC), two times higher than that in thermal ALD. At a temperature higher than 750 C, however, the GPC for both the LALD and conventional ALD processes decreased, probably due to thermal desorption of precursors.…”

Cancer Cell–Membrane Biomimetic Boron Nitride Nanospheres for Targeted Cancer Therapy

“…[2][3][4][5][6] Recently, boron nitride nanomaterials have drawn extensive attention from the academic community. 7,8 As a promising novel inorganic nanomaterial, boron nitride has been applied in many biomedical fields. 9,10 Boron nitride has a hexagonal structure similar to that of graphene, and possesses remarkable properties of biocompatibility, corrosion resistance, and large thermal neutroncapture cross-sections.…”

Atomic layer deposition of rhodium and palladium thin film using low-concentration ozone

“…Depositions of Pd thin lm coordinated with H 2 (ref. 31 and 32 ) and formalin 33,34 on Al 2 O 3 have been proven feasible. However, in those studies, the growth of Pd thin lm was hampered by Al(hfac) surface species, leading to a longer nucleation period and growth delay at the beginning of the ALD process.…”