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6 Single‐Atom Heterogeneous Catalysts
Yaxin Chen, Zhen Ma, and Xingfu Tang
Fudan University, Department of Environmental Science & Engineering, 2005 Songhu Rd., Shanghai, 200438, PR China
6.1 Introduction
Supported noble metal catalysts have been widely used in the production of chemicals [1], the remediation of environmental pollution [2, 3], and the processing of fuels [4, 5]. However, it is still desirable to increase the efficiency of supported noble metal catalysts due to the high prices and limited supplies of noble metals. To achieve this goal, one may attempt to design better supported catalysts by decreasing the content of the noble metals while maintaining their high catalytic efficiency. Thus, the sustainability of related industries can be improved, and the costs of production can be minimized.
Liang et al. gave an example to illustrate the advantage of supported noble metal catalysts over bulk metals (Figure 6.1) [6]. Assuming that the price of pure gold is US$ 38.1 g−1, a gold brick with the dimensions of 20 × 10 × 5 cm3 is worth approximately US$ 736 000. For comparison, if a common brick (20 cents) with the same dimensions is coated with an atomic ultrathin layer of gold (1 cent), the total value of the brick is only 21 cents (if the cost of coating processing is not counted), much lower than that of a gold brick. Thus, dispersing noble metals as ultrafine nanoparticles (NPs), clusters, or single atoms (SAs) on solid supports is effective for the efficient use of noble metals and the minimization of catalysts' costs. Then what is the effect of downsizing metal NPs on the catalytic activity of supported metal catalysts?