A cage-confinement strategy to fabricate Pt-Mo6Co6C heterojunction for highly efficient PH-universal hydrogen evolution.

A molecular-cage strategy is employed to encapsulate H 3 PMo 12 O 40 into cavities of ZIF-67. The fabricated Pt-Mo 6 Co 6 C heterojunctions uniformly embedded on dodecahedron carbon matrix and exhibit superior HER activity and stability than commercial Pt/C in universal PH solutions. [Display omitted] • A cage-confinement strategy was employed to encapsulate H 3 PMo 12 O 40 cluster into cavities of ZIF-67 without destroy its structure. • The Mo 6 Co 6 C nanoparticles was homogeneously embedded on dodecahedron carbon matrix without aggregation during pyrolysis process. • The Pt-Mo 6 Co 6 C heterojunction was fabricated through galvanic replacement which presents superior HER activity than commercial Pt/C in PH-universal solutions. • DFT calculation suggested that hydrogen adsorption free energy (ΔG H*) of Pt-Mo 6 Co 6 C heterojunction delivered a closer value to 0 eV than metallic Pt. Electrochemical water splitting has been highly considered as a promising technology to produce hydrogen with high purity and large quantity. Herein, a cage-confinement strategy is proposed to encapsulate H 3 PMo 12 O 40 clusters into cavities of ZIF-67. The ZIF-67 with cavity diameter of 1.16 nm and cavity window of 0.34 nm can appropriately confine H 3 PMo 12 O 40 with diameter of 1.0 nm. The H 3 PMo 12 O 40 served as guest species were also homogeneously encapsulated in well-defined cavities of ZIF-67 host without destroying the structure of ZIF-67. This cage-confinement strategy endow Mo 6 Co 6 C nanoparticles uniformly embedded in carbon matrix without aggregation and exposed abundant active sites during pyrolysis process. Furthermore, the heterojunction of Pt-Mo 6 Co 6 C was fabricated through galvanic replacement with H 2 PtCl 6. The prepared Pt-PMo/ZIF-67-800 electrocatalyst with a low Pt amount of 3.0 % exhibits excellent HER activity and stability and even superior to commercial Pt/C in PH-universal solutions. Density functional theory (DFT) calculation reveals that Pt-Mo 6 Co 6 C heterostructure results in a lower hydrogen adsorption free energy than commercial Pt/C and thus enhances its intrinsic catalytic activity. The outstanding HER performance of Pt-Mo 6 Co 6 C heterostructure confined on dodecahedron carbon matrix opens new perspectives for rational design polyoxometalate (POM) based catalyst for hydrogen evolution. [ABSTRACT FROM AUTHOR]