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

摘要

Hierarchical core-shell SnO2/Ag/Co(OH)2 spheres have been synthesized for efficient oxygenevolution reaction (OER) in alkaline solution using Ag-modified SnO2 hollow spheres (SnO2/Ag) assupport. SnO2/Ag hollow spheres can provide not only large surface area for the growth of Co(OH)2but also better conductivity and stability derived from Ag. XRD shows the formation of amorphousCo(OH)2 supported on SnO2/Ag. XPS confirms the existence and valence state of Sn, Ag and Co. EDXand SEM elemental mapping show the composition and good distribution of Sn, O, Ag and Co. SEMand TEM show that the wrinkled Co(OH)2 nanosheets homogeneously covered on the surface ofSnO2/Ag hollow spheres, which implying more exposed active sites. OER measurements show thatSnO2/Ag/Co(OH)2 has the enhanced performances with lower onset potential (1.4 V vs. RHE), smallerTafel slope (80.04 mV dec-1) than SnO2/Co(OH)2 and unsupported Co(OH)2. Ag modification may bethe key for enhancement performances for OER due to providing faster electron transfer rate. Theexcellent long-time stability of SnO2/Ag/Co(OH)2 may be ascribed to the close combination betweenCo(OH)2 and SnO2/Ag and stability of Ag in alkaline solution. The suitable support with gooddispersion and conductivity can provide a facile way to prepare effective electrocatalysts for OER.