Cobalt-doped ferrihydrite with silicon content for efficient decomposition of ozone under dry and humid conditions

Abstract

Background

Recently, the problem of ground-level ozone (O₃) pollution seriously endangers the health of human. The development of an effective catalyst for the catalytic decomposition of ozone at low temperatures is urgent but challenging.

Methods

This research aimed to develop a cobalt-doped silicon-containing ferrihydrite (Fh) catalyst (Co-SiFh) by a simple coprecipitation method. As comparisons, the single cobalt-doped and silicone-stabilized Fh were also prepared. ICP-OES, XRD, FT-IR, XPS, H₂-TPR, O₂-TPD were used to characterize the chemical structure of the different catalysts. Besides the catalytic performance test, in situ reaction experiments were used to explore the catalytic reaction mechanism.

Significant findings

Compared with the original Fh catalyst, the ozone conversion of Co-Sifh increased from ca. 95 % to ca. 100 % and from ca. 3 % to ca. 80 % under dry and humid conditions, respectively. Moreover, the Co-SiFh catalyst also maintained stable catalytic ozone degradation effect in a long-term reaction progress of 30 h. The excellent catalytic performance of the catalyst in humid airflow is attributed to the newly formed hydroxyl active sites around Co-O-Fe through the strong interaction between Fe and Co. In addition, the specific active site (O*-H₂O) in the modified catalyst is also a key factor to improve the moisture resistance of Fh.