Interfacial charge transfer on hierarchical synergistic shell wall of MXene/MoS2 on CdS nanospheres: heterostructure integrity for visible light responsive photocatalytic H2 evolution

Abstract

Energy scarcity and environmental pollution have prompted research in hydrogen generation from solar to develop clean energy through highly efficient, effective, and long-lasting photocatalytic systems. Designing a catalyst with robust stability and an effective carrier separation rate was achieved through heterostructure assembly, but certain functionalities must be explored. In this paper we designed a ternary heterostructure assembly of CdS nanospheres wrapped with hierarchical shell walls of layered MXene-tagged MoS2 nanoflakes, forming intimate interfaces through an in-situ growth process. An in-layered shell wall of MXene with surface-wrapped MoS2 nanoflakes as a core-shell assembly improved the photo-corrosion resistance and accelerated the production of photocatalytic H-2 (38.5 mmol g(-1) h(-1)), which is 10.7, 3.1, and 1.9 times faster than that of CdS, CdS-MXe, and CdS-MoS2 nanostructures, respectively. The apparent quantum efficiency of the CdS-MXe2.4/MoS2 heterostructure was calculated to be 34.6% at lambda = 420 nm. X-ray and ultraviolet photoelectron spectroscopies validated the electronic states, energy band alignment, and work function of the heterostructures, whilst time-resolved photoluminescence measured the carrier lifespan to evaluate the effective charge migration in the CdS-MXe/MoS2 heterostructure. The dual surface wrapping of MXe/MoS2 over CdS nanospheres confirmed the structural durability that remained intact throughout the photocatalytic reaction, promoting approximately 93.1% of its catalytic property even after five repeatable cycles. This study examined how the MXene heterostructure template improves the catalytic efficiency and opens a new way to design MXene-based durable heterostructure catalysts for solar-energy conversion.