Highly efficient photocatalytic hydrogen generation of PtPdy nanoframe/2D-CdS: Shape-controlled preparation and property modulation

Abstract

This work focuses on the structure design of Pt-based alloys, and their influences on 2D-CdS semiconductor photocatalyst in hydrogen (H2) generation reaction from water-splitting under visible light, using traditional experimental techniques and DFT calculations as Pd concave nanocube (Pd CNCs) as a template, PtPdx alloy with cuboctahedron core-shell structure (PtPdx NPs) and cuboctahedron nanoframe (PtPdy NFs) were successfully synthesized via wet chemical routes. The structure of Pt-based alloys was certified by XRD, HRTEM, XPS, and ICP. The Pt-based co-catalysts were photo-deposited on 2D-CdS in an aqueous solution of (NH4)2SO3 while the reaction for photo-generating of H2 occurred. The obtained photocatalysts show excellent activity towards hydrogen generation, i.e., in ascending order, Pd CNCs/2D-CdS (46.1 mmol/h/g) < PtPd1.8 NPs/2D-CdS (55.4 mmol/h/g) < PtPd0.2 NFs/2D-CdS (71.7 mmol/h/g, QE=61.46%, λ=420 nm). Photoelectrochemical tests, ESR, and work functions results indicate that PtPd0.2 NFs have excellent photoelectrochemical performance, the longest lifetime of electrons, and the highest work function, respectively. Moreover, DFT calculations unveil that PtPd0.2 has the largest surface energy and the lowest activation energy ΔGH* which results in the fast charge transfer rate at the PtPd0.2/2D-CdS interface. This work offers a novel thought into the structural design of Pt-based co-catalysts applied in photocatalytic hydrogen generation from water-splitting.