Surface Facet of CuFeO 2 Nanocatalyst: A Key Parameter for H 2 O 2 Activation in Fenton-Like Reaction and Organic Pollutant Degradation

The development of efficient heterogeneous Fenton catalysts is mainly by “trial-and-error” concept and the factor determining H 2 O 2 activation remains elusive. In this work, we demonstrate that suitable facet exposure to elongate O–O bond in H 2 O 2 is the key parameter determining the Fenton catalyst’s activity. CuFeO 2 nanocubes and nanoplates with different surface facets of {110} and {012} are used to compare the effect of exposed facets on Fenton activity. The results indicate that ofloxacin (OFX) degradation rate by CuFeO 2 {012} is four times faster than that of CuFeO 2 {110} (0.0408 vs 0.0101 min –1 ). In CuFeO 2 {012}-H 2 O 2 system, OFX is completely removed at a pH range 3.2–10.1. The experimental results and theoretical simulations show that • OH is preferentially formed from the reduction of absorbed H 2 O 2 by electron from CuFeO 2 {012} due to suitable elongation of O–O (1.472 Å) bond length in H 2 O 2 . By contrast, the O–O bond length is elongated from 1.468 to 3.290 Å by CuFeO 2 {110} facet, H 2 O 2 tends to be dissociated into −OH group and passivates {110} facet. Besides, the new formed ≡Fe 2+ * on CuFeO 2 {012} facet can accelerate the redox cycle of Cu and Fe species, leading to excellent long-term stability of CuFeO 2 nanoplates.