Enhanced and stabilized hydrogen production from methanol by ultrasmall Ni nanoclusters immobilized on defect-rich h-BN nanosheets

Abstract

Employing liquid organic hydrogen carriers (LOHCs) to transport hydrogen to where it can be utilized relies on methods of efficient chemical dehydrogenation to access this fuel. Therefore, developing effective strategies to optimize the catalytic performance of cheap transition metal-based catalysts in terms of activity and stability for dehydrogenation of LOHCs is a critical challenge. Here, we report the design and synthesis of ultrasmall nickel nanoclusters (∼1.5 nm) deposited on defect-rich boron nitride (BN) nanosheet (Ni/BN) catalysts with higher methanol dehydrogenation activity and selectivity, and greater stability than that of some other transition-metal based catalysts. The interface of the two-dimensional (2D) BN with the metal nanoparticles plays a strong role both in guiding the nucleation and growth of the catalytically active ultrasmall Ni nanoclusters, and further in stabilizing these nanoscale Ni catalysts against poisoning by interactions with the BN substrate. We provide detailed spectroscopy characterizations and density functional theory (DFT) calculations to reveal the origin of the high productivity, high selectivity, and high durability exhibited with the Ni/BN nanocatalyst and elucidate its correlation with nanocluster size and support–nanocluster interactions. This study provides insight into the role that the support material can have both regarding the size control of nanoclusters through immobilization during the nanocluster formation and also during the active catalytic process; this twofold set of insights is significant in advancing the understanding the bottom-up design of high-performance, durable catalytic systems for various catalysis needs.

Low-Temperature Synthesis of Single Palladium Atoms Supported on Defective Hexagonal Boron Nitride Nanosheet for Chemoselective Hydrogenation of Cinnamaldehyde

“…43,44 As shown in SI Figure S9, the peak at 1367 cm −1 corresponds to the high-frequency interlayer Raman active E 2g mode. 35 The peak intensity of bulk h-BN was the highest among the samples. This suggests after exfoliation, the thickness of the h-BN nanosheet was reduced and defects were created.…”

“…The peaks intensity of bulk h-BN is stronger than that of the exfoliated h-BN, implying the lower stacking level of h-BN nanosheet. 35 Typical metallic palladium peaks are noticed on Pd NPs/h-BN (Figure 3a, SI Figure S8), whereas none was observed on Pd 1 /h-BN. Raman tests were carried out to detect the defects in graphene-like materials.…”

Multiple Promotional Effects of Vanadium Oxide on Boron Nitride for Oxidative Dehydrogenation of Propane

“…The characteristic G band of BN, namely, the interlayer Raman active E 2g mode, is observed at 1370.8 cm –1 for fresh BN, while the band slightly red shifts to 1369.8 cm –1 for 0.75V/BN-T, implying the VO x -induced localized fixation effect on reduced in-plane strain ( Figure S10 ). 32 Figure 3 A shows the Raman spectra of dehydrated VO x /BN-T catalysts. The two peaks, centered at 819 and 922 cm –1 , are not due to any fundamental modes of h-BN but have been observed in previous studies with UV Raman.…”

2D Boron Nitride Heterostructures: Recent Advances and Future Challenges

“…In a similar study, nickel (Ni) nanoclusters (ultrasmall size, ≈1.5 nm) have been immobilized on defect‐rich h‐BN sheets for improving hydrogen production from methanol. [ 12 ] The bulk precursor has been preexfoliated by thermal treatment at 800 °C followed by immersion in liquid nitrogen to obtain h‐BN sheets with abundant oxygen vacancies. Sonication in a solution of tetrahydrofuran (THF) and lithium–naphthalenide produces the final exfoliation.…”

“…[ 10,11 ] Although obtaining a less‐defective h‐BN layer is an important technological task, several of the functional properties of h‐BN in the 2D form depends on the presence of defects, which can be of different nature. [ 12,13 ] Furthermore, multiple defects can co‐occur, such as carbon, oxygen and hydrogen impurities, boron/nitrogen vacancies. [ 14 ] The defects are also not homogeneously distributed in the material, while the edges also play a primary role because of dangling bonds.…”