The ultrathin hollow core-shell heterojunction in Co3O4/Ti3 + -TiO2/Cd0.8Zn0.2S towards enhanced overall water splitting and photodegradation via synergism of HER/OER matching and Ti3+/Ov-bimetallic affect

The hydrogen evolution reaction/oxygen evolution reaction (HER/OER) kinetic equilibrium is the fundamental issue for overall water splitting. The Co 3 O 4 /Ti 3+ -TiO 2 /Cd 0.8 Zn 0.2 S hollow core-shell heterojunction is fabricated by an approach of chemical-annealing-reduction-hydrothermal method via ZIF-67 auxiliary. The prepared Co 3 O 4 /Ti 3+ -TiO 2 /Cd 0.8 Zn 0.2 S shows signally increased HER (∼5717.57 μmol∙g −1 ∙h −1 )/photodegradation(∼0.04980 min −1 ) than that of TiO 2 (∼90/15 folds), Cd 0.8 Zn 0.2 S (∼70/10 folds) and Co 3 O 4 (∼115/30 folds), achieves overall water splitting of ∼321.90(H 2 )/159.52(O 2 ) μmol∙g −1 ∙h −1 , and shows a good stability. It is primarily ascribed to the synergism of HER/OER matching, Ti 3+ /O v -bimetallic affect and hollow structure. In this system, the Ti 3+ /O v owns increased solar efficiency and potential barrier regulation for HER, the Co 3 O 4 owns H 2 O 2 decomposition and anion absorption for OER, the Ti 3+ -TiO 2 /Cd 0.8 Zn 0.2 S heterojunction owns bimetallic affect and potential gradient to improve carrier efficiency, including increasing transport, extending lifetime, and reducing recombination, as well as the hollow core-shell structure can increase structural stability and active sites for inhibiting photocorrosion. With the matched kinetic equilibrium, the Co 3 O 4 /Ti 3+ -TiO 2 /Cd 0.8 Zn 0.2 S achieves remarkable overall water splitting. • HER/OER synergism shows overall water splitting ∼321.9(H 2 )/159.52(O 2 ) μmol∙g −1 ∙h −1 • Ti 3+ /O v with potential regulation for solar efficiency/electron diffusion(0.093 eV). • Co 3 O 4 can increase H 2 O 2 decomposition and anion absorption for OER. • Heterojunction provide appropriate potential gradient (0.721 eV). • Hollow core-shell structure can increase active sites, solar efficiency, stability.