The Ni2+-LaNiO3/CdS hollow core–shell heterojunction towards enhanced visible light overall water splitting H2 evolution via HER/OER synergism of Ni2+/Ov

[Display omitted] •HER/OER synergism of Ni2+/Ov is the core issue for overall water splitting.•Ni2+ ions with high solar efficiency and rapidly electron diffusion can promote HER.•Ov can decrease OER energy barrier and promote holes transportation for OER.•Heterojunction with appropriate potential gradient can improve carrier efficiency.•Hollow core–shell structure can increase active sites and solar efficiency. The synergetic HER/OER (hydrogen evolution reaction/oxygen evolution reaction) is the crucial issue for overall water splitting. Herein, the Ni2+-LaNiO3/CdS hollow core–shell heterojunction with HER/OER synergism of Ni2+/Ov (oxygen vacancy) is synthesized by a hybrid hydrothermal-reductive-chemical method. As shown, the Ni2+-LaNiO3/CdS (∼15480.79 μmol∙g−1∙h−1) exhibits an obvious visible light photocatalytic enhancement (HER/Photodegradation) than that of single LaNiO3 (∼200/∼15 folds) and single CdS (∼120/∼6 folds), and achieves a better overall water splitting performance of ∼ 645.23(H2)/321.62(O2) μmol∙g−1∙h−1 (∼110 folds of LaNiO3), and a respectable stability (∼5.64% decreasing during 24 h). It mainly ascribes to the synergetic HER/OER via the Ni2+/Ov, formed heterojunction and hollow core–shell structure. There, the Ni2+ ions can increase solar efficiency and promote photo-generated electron diffusing for HER, the Ov induced by Ni2+ can decrease OER energy barrier and promote hole­related species transportation for OER, the LaNiO3/CdS heterojunction with appropriate potential gradient can improve carrier efficiency, and the hollow core–shell structure can increase active sites and solar efficiency. Furthermore, the quickly carrier diffusion can inhibit photocorrosion and hollow spherical structure can increase photocatalytic stability.