Cobalt silicate hydroxide nanosheets in hierarchical hollow architecture with maximized cobalt active site for catalytic oxidation

A facile dissolution-regrowth strategy was developed in synthesis of hierarchical hollow nanospheres of cobalt silicate hydroxide (CSH-80) for maximizing cobalt active sites on unit mass basis, which is different from the conventional supported cobalt catalysts. Due to the unique design and elaborative nanoarchitecture, the cobalt active center can be homogeneously dispersed into the structured catalyst, achieving the maximum exposure of the cobalt center for reaction. In activation of peroxymonosulfate (PMS) for degradation of organic contaminants, CSH-80 exhibited outstanding catalytic performance, excellent physicochemical stability and long-term durability, giving 1.9-3.1 folds higher efficiency than that of the conventional supported cobalt catalysts. The turnover frequency of CSH-80 in organic oxidation was 2.0-3.2 folds higher than that of the conventional supported cobalt catalysts. The effects of reaction parameters on contaminant degradation were systematically investigated. The catalytic oxidation mechanism was further elucidated by the quenching tests, electron paramagnetic resonance and photoluminescence studies. The design concept in this study will provide new opportunities for future development of high-performance cobalt-based heterogeneous catalysts in environmental remediation.