Molten salt synthesis of 1T phase dominated O-MoS2 for enhancing photocatalytic hydrogen production performance of CdS via Ohmic junction.

Abstract

In photocatalysis, establishing an Ohmic junction could create an internal electric field between semiconductors and cocatalysts [1,2], effectively enhancing the transfer of photogenerated electrons. In this study, the 1T phase dominated oxygen atom doped MoS₂ cocatalyst (O-MoS₂), synthesized from KSCN molten salt with in-situ oxidation for the first time, is combined with CdS for boosting photocatalytic hydrogen production. In the hybrid photocatalyst, electrons could be efficiently extracted from CdS to O-MoS₂ due to the presence of Ohmic contact, thereby significantly enhancing the utilization of photogenerated electrons and the photocatalytic hydrogen evolution performance. The results demonstrate that an initial hydrogen evolution rate of 532.8 μmol^-1 could be achieved for CdS with the optimum loading amount of O-MoS₂ (CdS-5), 26.6 times higher than that of CdS alone. Additionally, CdS-5 exhibits an apparent quantum yield (AQY) of 80.4 % at 420 nm. The increased photocatalytic performance of CdS-5 is primarily attributed to the efficient electron transfer (ET) process between the CdS and O-MoS₂ in the presence of Ohmic junction, which accelerates the separation of the photogenerated carriers from CdS. It is strongly confirmed by the (photo)electrochemical experiments, steady-state/time-resolved photoluminescence (PL) spectra, Kelvin probe force microscope (KPFM), femtosecond transient absorption spectra (fs-TAS) and Density functional theory (DFT) calculation.