Facile Transformation of Ni‐based Colloids into Highly Stable Nanocatalysts Embedded within h‐BN for the Water‐Gas Shift Reaction

Abstract

Advances in colloidal chemistry allow to prepare well‐controlled nanostructures, while application of the colloids in heterogeneous catalysis is strongly impeded by the presence of organic capping layers. However, removal of the protection layers inevitably results in changes of the well‐defined nanostructures such as sintering and agglomeration. Here, a simple way is suggested to solve the dilemma by replacing the organic capping layers with another flexible but robust capping layers made of two‐dimensional materials. We show simultaneous removal of surfactant layers in B‐containing Ni, Co, and Fe colloids and formation of hexagonal boron nitride (h‐BN) capping layers over metal nanoparticles. Metal particle size can be well kept even upon thermal treatment at 850 °C and Ni nanocatalysts embedded within h‐BN shells present high catalytic performance in water‐gas shift reaction. This work suggests a facile strategy to promote the application of metal colloids in heterogeneous catalysis.

Designing Nanoparticles and Nanoalloys for Gas-Phase Catalysis with Controlled Surface Reactivity Using Colloidal Synthesis and Atomic Layer Deposition

“…While Ni [194] is a cost-effective alternative to noble metal-based [195] catalysts, it suffers from two intrinsic drawbacks under WGS conditions [196]: simultaneous CH 4 formation, which restricts the H 2 yield; and sintering of Ni. As a solution to these problems, Gao et al [197] synthesized core-shell hexagonal boron nitride (h-BN)-encapsulated Ni NPs through a facile thermal NH 3 treatment of PVP-capped Ni NPs. These core-shell Ni@h-BN catalysts retained their particle size under thermal treatments up to 850 • C and showed high WGS activity at low temperatures (~250 • C).…”

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

“…Catalytic activity promoted by confinement effect is reported with various metal@ h- BN nanostructures in electrochemical reaction, CO methanation, water–gas shift reaction, and CO oxidation. ,− In situ characterization and DFT calculations indicate that the interactions of the O, H, and OH intermediate species with the Ni surface are weakened by the h- BN shell, which are proposed to be critical factors for optimum hydrogen oxidation reaction (HOR) performance. As shown in Figure c, the exchange current density of HOR by Ni@ h- BN with moderate thickness overlayers is six times greater than that of the bare Ni catalyst even after the accelerated durability tests …”