PNNL

Abstract

An important goal of heterogeneous catalyst synthesis is the dispersion of the active metal uniformly on a catalyst support, ideally achieving atomic dispersion. Isolated single atoms dispersed on oxide supports provide efficient utilization of scarce platinum group metals (PGMs). The enhanced reactivity of Pt1/FeOx by Qiao et al. [1] generated a lot of excitement in this field and helped set in motion the field of single atom catalysis (SAC). Since then we see numerous reports of higher reactivity and better selectivity for SACs in a range of catalytic reactions. Synthesis methods for depositing transition metals, through strong electrostatic adsorption (SEA), ion exchange, co-precipitation, grafting, impregnation or deposition-precipitation are well developed. To generate and maintain single-atom catalysts using these currently available methods, it is necessary to use low metal loading, and to limit the operating temperatures to prevent agglomeration of single atoms into nanoparticles [2]. For industrial applications, it would be desirable to achieve high metal loadings and stable performance at high temperatures, which can be achieved by the methods of atom trapping that we describe here.