Engineering Nanostructured Interfaces of Hexagonal Boron Nitride-Based Materials for Enhanced Catalysis

Abstract

Hexagonal boron nitrides (h-BNs) are attractive two-dimensional (2D) nanomaterials that consist of alternating B and N atoms and layered honeycomblike structures similar to graphene. They have exhibited unique properties and promising application potentials in the field of energy storage and transformation. Recent advances in utilizing h-BN as a metal-free catalyst in the oxidative dehydrogenation of propane have triggered broad interests in exploring h-BN in catalysis. However, h-BN-based materials as robust nanocatalysts in heterogeneous catalysis are still underexplored because of the limited methodologies capable of affording h-BN with controllable crystallinity, abundant porosity, high purity, and defect engineering, which played important roles in tuning their catalytic performance. In this Account, our recent progress in addressing the above issues will be highlighted, including the synthesis of high-quality h-BN-based nanomaterials via both bottom-up and top-down pathways and their catalytic utilization as metal-free catalysts or as supports to tune the interfacial electronic properties on the metal nanoparticles (NPs). First, we will focus on the large-scale fabrication of h-BN nanosheets (h-BNNSs) with high crystallinity, improved surface area, satisfactory purity, and tunable defects. h-BN derived from the traditional approaches using boron trioxide and urea as the starting materials generally contains carbon/oxygen impurities and has low crystallinity. Several new strategies were developed to address the issues. Using bulk h-BN as the precursor via gas exfoliation in liquid nitrogen, single-or few-layered h-BNNS with abundant defects could be generated. Amorphous h-BN precursors could be converted to h-BN nanosheets with high crystallinity assisted by a magnesium metallic flux via a successive dissolution/precipitation/crystallization procedure. The as-fabricated h-BNNS featured high crystallinity and purity as well as abundant porosity. An ionothermal metathesis procedure was developed using inorganic molten salts (NaNH 2 and NaBH 4 ) as the precursors. The h-BN scaffolds could be produced on a large scale with high yield, and the asafforded materials possessed high purity and crystallinity. Second, utilization of the as-prepared h-BN library as metal-free catalysts in dehydrogenation and hydrogenation reactions will be summarized, in which they exhibited enhanced catalytic activity over the counterparts from the previous synthesis method. Third, the interface modulation between metal NPs with the as-prepared defects' abundant h-BN support will be highlighted. The h-BN-based strong metal−support interaction (SMSI) nanocatalysts were constructed without involving reducible metal oxides via the ionothermal procedure we developed by deploying specific inorganic metal salts, acting as robust nanocatalysts in CO oxidation. Under conditions simulated for practical exhaust systems, promising catalytic efficiency together with high thermal stability and sintering resistance was achieved. Across all of these ...

Nonclassical Strong Metal–Support Interactions for Enhanced Catalysis

“…81 This can be counterintuitive as h-BN itself is known for compelling stability under oxidizing conditions. 82 For the h-BN-supported metal catalyst, the interfacial metal sites function as the autocatalytic sites triggering oxidative etching. Fu and co-workers discovered that the h-BN-supported Ni nanoparticles become encapsulated by atomically thin boron oxide (BO x ) layers during the methane dry reforming reaction.…”

“…Controllable surface oxidation of h -BN also gives rise to unanticipated surface reactivities driving SMSI . This can be counterintuitive as h -BN itself is known for compelling stability under oxidizing conditions . For the h -BN-supported metal catalyst, the interfacial metal sites function as the autocatalytic sites triggering oxidative etching.…”

Boron Nitride- and Carbon-Supported Iridium–Iron Catalysts for Synthesizing Mono-Alcohols from Biomass-Derived Vicinal Diols

“…Hexagonal boron nitride (h-BN), the most stable crystal form of BN under standard conditions, has been widely applied to the fields of physics and electronics due to its optoelectrical properties and structural stability . Likewise, in the catalysis field, h-BN with prospective application potentials has gradually attracted attention owing to the promoting support–metal-interaction effect of h-BN such as electron transfer, geometric effect, encapsulation, and synergistic effect. , h-BN has been reported to be effective in various reactions such as oxidative dehydrogenation of propane to propene (h-BN as a catalyst or support), dry reforming of methane (BO x encapsulation overlayers as a promoter), and hydrogenation of crotonaldehyde, nitro aromatics, hydroxymethylfurfural, esters, CO 2 , and 1-hexyne (h-BN as support). However, applications of h-BN to the hydrogenolysis of polyols are very limited.…”

Highly Dispersed Ru Nanoclusters Anchored on Hexagonal Boron Nitride for Efficient and Stable Hydrogenation of Aromatic Amines to Alicyclic Amines

“…As a structural and isoelectronic analog of graphene, hexagonal boron nitride (h-BN) possesses high mechanical strength and thermal conductivity. , Compared to graphene, h-BN has gained attention as a catalyst carrier in various heterogeneous catalytic reactions. For instance, h-BN has been utilized in the oxidation of alcohols, benzene hydrogenation of nitroaromatic amines, selective hydrogenation of α-β-unsaturated aldehydes, and semihydrogenation of alkynes . Additionally, the two-dimensional structure h-BN has proven to be a fitting support for supported metal catalysts. , For instance, Zhang et al prepared a series of Pd@h-BN composite materials using modified BN as the carrier to achieve a suitable hydrogen overflow and successfully used benzaldehyde in a hydrogenation reaction .…”