Insights into structural properties of Cu species loaded on Bi2O3 hierarchical structures for highly enhanced photocatalysis

- Significant photocatalytic activity enhancement for Bi2O3 by Cu loading is observed.
- High loading of Cu is detrimental to photocatalytic activity.
- Cu is loaded onto the Bi2O3 surface in the form of amorphous nanoclusters.
- Cu exists solely in the +2 oxidation state.
- Cu is coordinated to four oxygen atoms with bond lengths of ∼1.93 Å.

Pristine Bi2O3 is known to possess poor photocatalytic activity due to its low conduction band potential. Here, we attempt to enhance the photocatalytic activity of Bi2O3 by loading Cu species through a very simple impregnation method. After Cu loading at the optimum amount, we observe significant enhancements of photocatalytic activity for degradation and mineralization of atrazine under visible light by maximum factors of 9.4 (0.2 wt.% Cu) and 11.7 (0.1 wt.% Cu), respectively. Microstructural properties of Bi2O3 are not altered upon Cu loading, yet its light absorption ability is greatly improved. On the basis of EXAFS and XANES analysis, we suggest that Cu species exists in the +2 oxidation state, coordinated with four O atoms with bond lengths of ∼1.93 Å in the form of amorphous nanoclusters.

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