Stabilization of Exposed Metal Nanocrystals in High-temperature Heterogeneous Catalysis.

Colloidal metal nanocrystals with uniform sizes, shapes, compositions and architectures are ideal building blocks for constructing heterogeneous catalysts with well-defined characteristics towards the investigation of accurate structure-property relationships and better understanding of catalytic mechanism. However, their applications in high-temperature heterogeneous catalysis are often restricted by the difficulty in maintaining the high metal dispersity and easy accessibility to active sites under harsh operating conditions. Here, we propose a partial-oxide-coating strategy to stabilize metal nanocrystals against sintering and meanwhile enable an effective exposure of active sites. As a proof-of-concept, we demonstrate controlled partial silica coating of colloidally prepared Pd0.82 Ni0.18 nanocrystals with the size of 8 nanometers. This partially coated catalyst exhibits excellent activity, selectivity and stability, outperforming its counterparts with fully coated and supported structures, in reverse water gas shift catalysis particularly at high operating temperatures. Our study opens a new avenue for the exploration of colloidal metal nanocrystals in high-temperature heterogeneous catalysis. This article is protected by copyright. All rights reserved.