Oxidative Strong Metal–Support Interactions between Metals and Inert Boron Nitride

Abstract

The strong metal−support interaction (SMSI) is one of the most important concepts in heterogeneous catalysis, which has been widely investigated between metals and active oxides triggered by reductive atmospheres. Here, we report the oxidative strong metal− support interaction (O-SMSI) effect between Pt nanoparticles (NPs) and inert hexagonal boron nitride (h-BN) sheets, in which Pt NPs are encapsulated by oxidized boron (BO x ) overlayers derived from the h-BN support under oxidative conditions. De-encapsulation of Pt NPs has been achieved by washing in water, and the residual ultrathin BO x overlayers work synergistically with surface Pt sites for enhancing CO oxidation reaction. The O-SMSI effect is also present in other h-BN-supported metal catalysts such as Au, Rh, Ru, and Ir within different oxidative atmospheres including O 2 and CO 2 , which is determined by metal−boron interaction and O affinity of metals.

Hexagonal Boron Nitride Meeting Metal: A New Opportunity and Territory in Heterogeneous Catalysis

“…25−27 Furthermore, atmosphere-induced etching of h-BN at the metal/h-BN interfaces and subsequent encapsulation of metal nanoparticles (NPs) by h-BN-derived boron oxide overlayers are discovered in many metal/h-BN systems. 28,29 The finding expands the classical strong metal−support interaction (SMSI) effect from oxide supports to h-BN supports. Finally, metal catalysts covered by few-layer h-BN (metal@h-BN) are designed as nanoreactors to modulate the metal surfaces by 2D confinement effect.…”

“…Further investigations with other transition metals indicate the universality of the O-SMSI effect in metal/ h- BN systems . The necessary atmosphere to induce the O-SMSI phenomena is O 2 for Au, Ag, and Pt but CO 2 for Ni, Fe, Co, Ru, Rh, and Ir.…”

“…Multiple methods, , such as chemical exfoliation, solid-phase synthesis, and surface functionalization, are developed to synthesize h- BN nanomaterials with abundant edges, B/N vacancies, and surface functional groups, which are able to anchor and modify supported metal nanocatalysts, even single-atom catalysts (SACs). The metal/ h -BN interfacial MSI effects, including electron transfer, geometric effect, encapsulation, and synergistic mechanism, contribute to the promoted catalysis. − Furthermore, atmosphere-induced etching of h- BN at the metal/ h- BN interfaces and subsequent encapsulation of metal nanoparticles (NPs) by h- BN-derived boron oxide overlayers are discovered in many metal/ h- BN systems. , The finding expands the classical strong metal–support interaction (SMSI) effect from oxide supports to h- BN supports. Finally, metal catalysts covered by few-layer h- BN (metal@ h- BN) are designed as nanoreactors to modulate the metal surfaces by 2D confinement effect. , Different metal/ h- BN interfaces are summarized in Figure , indicating the impressive potential of h- BN as catalyst supports/promoters.…”

“…Metals colored in red have shown the etching phenomena under corresponding atmospheres. Adapted with permission from ref . Copyright 2021 American Chemical Society.…”

“…Further investigations with other transition metals indicate the universality of the O-SMSI effect in metal/h-BN systems. 29 The necessary atmosphere to induce the O-SMSI phenomena is O 2 for Au, Ag, and Pt but CO 2 for Ni, Fe, Co, Ru, Rh, and Ir. Figure 4e shows these etching results, as well as the formation enthalpy of metal−boron alloy and oxygen affinity (pO) of metals.…”