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Published online: 23 July 2008 | doi:10.1038/nchina.2008.170

Carbon monoxide oxidation: Gold finds a partner

Felix Cheung

Introduction

© (2008) RSC

Gold, in bulk form, is completely inert. But when finely dispersed as nanoparticles on a supporting material, gold is a great catalyst for oxidizing highly toxic CO into non-toxic CO₂. Tao Zhang at the Chinese Academy of Sciences in Dalian and co-workers¹ have alloyed gold with copper to form a catalyst that is highly efficient in oxidizing CO.

A gold-plating (HAuCl₄) solution was poured onto a pre-treated mesoporous support, which was then reduced by a reducing agent (NaBH₄). After filtration and washing, the mesoporous support was dipped into a copper-plating (Cu(NO₃)₂) solution, and then reduced again. After further filtration, washing, drying and calcination, a gold–copper catalyst was obtained. The gold-to-copper ratio of the catalyst can be varied by adjusting the amount of HAuCl₄ and Cu(NO₃)₂ used.

The researchers characterized and measured the activity of the catalyst. They found that gold–copper nanoparticles were uniformly distributed in the channels of the support (pictured). Moreover, the particles were extremely fine — even smaller than when pure gold was used.

Alloying gold with copper allows oxygen to be adsorbed and activated more easily. The fineness and enhanced oxygen affinity gave the gold–copper catalyst a turnover rate superior to other catalysts. The catalyst remained active even below 0 °C and in hydrogen-rich environments, which would normally reduce the effectiveness of the catalyst.

It has been known that CO can 'poison' platinum catalysts in hydrogen fuel cells. The gold–copper catalyst is therefore a practical method for reducing CO down to tolerant levels.

The authors of this work are from:
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China; Graduate University of Chinese Academy of Sciences, Beijing, China; Department of Chemistry, National Taiwan University, Taipei, Taiwan.

Reference

1. Liu, X., Wang, A., Wang, X., Mou, C. Y. & Zhang, T. Au–Cu alloy nanoparticles confined in SBA-15 as a highly efficient catalyst for CO oxidation. Chem. Comm. 27, 3187–3189 (2008). | PubMed |