Bigger is not always better: Rhodium metal particles smaller than 2.5 nm are oxidized and stabilized by reducible supports such as ceria under CO oxidation conditions, whereas metal particles larger than 4 nm remain metallic. The very small Rh oxide particles are more active by two orders of magnitude in CO oxidation than Rh metal particles (see picture; TOF=turnover frequency).

中文翻译：

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负载的氧化铑纳米颗粒作为高活性CO氧化催化剂

更大并不总是更好：小于2.5 nm的铑金属颗粒在CO氧化条件下被可还原的载体（例如二氧化铈）氧化并稳定，而大于4 nm的金属颗粒则保持金属性。与Rh金属颗粒相比，非常小的Rh氧化物颗粒在CO氧化中的活性高两个数量级（参见图片； TOF =周转频率）。