Hierarchical Core-shell SnO2/Ag/Co(OH)2 Spheres Comprising Wrinkled Nanosheets for Highly Efficient Oxygen Evolution Reaction

Hierarchical core-shell SnO2/Ag/Co(OH)(2) spheres have been synthesized for efficient oxygen evolution reaction (OER) in alkaline solution using Ag-modified SnO2 hollow spheres (SnO2/Ag) as support. SnO2/Ag hollow spheres can provide not only large surface area for the growth of Co(OH)(2) but also better conductivity and stability derived from Ag. XRD shows the formation of amorphous Co(OH)(2) supported on SnO2/Ag. XPS confirms the existence and valence state of Sn, Ag and Co. EDX and SEM elemental mapping show the composition and good distribution of Sn, O, Ag and Co. SEM and TEM show that the wrinkled Co(OH)(2) nanosheets homogeneously covered on the surface of SnO2/Ag hollow spheres, which implying more exposed active sites. OER measurements show that SnO2/Ag/Co(OH)(2) has the enhanced performances with lower onset potential (1.4 V vs. RHE), smaller Tafel slope (80.04 mV dec(-1)) than SnO2/Co(OH)(2) and unsupported Co(OH)(2). Ag modification may be the key for enhancement performances for OER due to providing faster electron transfer rate. The excellent long-time stability of SnO2/Ag/Co(OH)(2) may be ascribed to the close combination between Co(OH)(2) and SnO2/Ag and stability of Ag in alkaline solution. The suitable support with good dispersion and conductivity can provide a facile way to prepare effective electrocatalysts for OER.