Selective etching of Sm0.5Sr0.5CoO3-δ ceramic for solar evaporator with photocatalytic purification

•The photo-thermal conversion material (Sm0.5Sr0.5CoO3-δ) carrying catalytic material (Co3O4) was prepared via a facile one-step nitric acid etching method.•The surface of Sm0.5Sr0.5CoO3-δ was selectively reconstructed through the acid-etching treatment and then the catalytic active cobalt cation was randomly exposed.•The acid-etched Sm0.5Sr0.5CoO3-δ exhibited a higher solar absorbance and better catalytic ability, which showed promising application in the pure water production.