Cobalt-based catalysts are highly promising for the oxygen evolution reaction (OER) in terms of both cost and performance. The dispersion state of Co 3 O 4 impacts the catalyst performances directly, while development of an efficient method for Co 3 O 4 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 Co 3 O 4 on the mesoporous silica (MS) SBA-15. The precursor of Co 3 O 4 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 Co 3 O 4 with extremely high dispersion after the decomposition of Co precursor. Up to 4 mmol of Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 corresponds to high activity in OER. The typical catalyst 4CoAS exhibits a potential of 0.73 V at 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.

Single-atom catalysts (SACs) show expressively enhanced activity toward diverse reactions due to maximized atomic utilization of metal sites, while their facile, universal, and massive preparation remains a pronounced challenge. Here we report a facile strategy for the preparation of SACs by use of the inherent confined space between the template and silica walls in template-occupied mesoporous silica SBA-15 (TOS). Different transition metal precursors can be introduced into the confined space readily by grinding, and during succeeding calcination single atoms are constructed in the form of M−O− Si (M = Cu, Co, Ni, and Zn). In addition to the generality, the present strategy is easy to scale up and can allow the synthesis of 10 g of SACs in one pot through ball milling. The Cu SAC has been applied for CO 2 cycloaddition of epichlorohydrin, and the activity is obviously higher than the counterpart prepared without confined space and various reported Cu-containing catalysts.

Solid superbases can catalyze diverse reactions under mild conditions, while they suffer from aggregation of basic sites and poor stability during recycling.Here we report a new generation of solid superbases derived from K single atoms (SAs) prepared by a tandem redox strategy. The initial redox reaction takes place between base precursor KNO 3 and graphene support, producing K 2 O at 400 °C. Further increasing the temperature to 800 °C, the graphene reduces K 2 O to K anchored by its vacancies, leading to the generation of K SAs (denoted as K 1 /G). The source of basicity in the K 1 / G is K SAs, and neighboring single atoms (NSAs) possess superbasicity, which is different from conventional basicity originated from oxygen and nitrogen atoms. Due to the superbasicity as well as high dispersion and anchoring of basic sites, the K 1 /G shows excellent catalytic activity and stability in transesterification reaction, which is much superior to the reported catalysts.