Highly Dispersive Cobalt Oxide Constructed in Confined Space for Oxygen Evolution Reaction

Cobalt-based catalysts are highly promising for the oxygen evolution reaction (OER) in terms of both cost and performance. The dispersion state of Co3O4 impacts the catalyst performances directly, while development of an efficient method for Co3O4 dispersion remains a pronounced challenge. In this study, it is the first time that the confined space strategy (CSS) is employed to make highly dispersive Co3O4 on the mesoporous silica (MS) SBA-15. The precursor of Co3O4 is successfully introduced into the confined space inherent in as-prepared SBA-15 (between the silica walls and the template). The CSS facilitates the formation of Co304 with extremely high dispersion after the decomposition of Co precursor. Up to 4 mmol of Co3O4 can be dispersed in per gram of MS without any X-ray diffraction lines (the obtained sample is denoted as 4CoAS), while obvious diffraction lines are detected in the counterpart prepared from calcined SBA-15 (the sample is denoted as 4CoCS). Further calculation indicates that the size of Co3O4 nanoparticles in 4CoCS is 9.8 nm, which is much larger than that in 4CoAS by using the CSS (below detection limits). Our results also show that high dispersion of Co3O4 corresponds to high activity in OER. The typical catalyst 4CoAS exhibits a potential of 0.73 Vat the current density of 10 mA.cm(-2). It is superior to that of 4CoCS (0.78 V) and of the reference catalyst 4Co(3)O(4)/CS (0.90 V) with the same Co content. Furthermore, the catalyst 4CoAS presents quite good stability in OER and is obviously better than 4CoCS.