Tailoring the fusion effect of phase-engineered 1T/2H-MoS towards photocatalytic hydrogen evolution

As a research hotspot, 2D-MoS 2 has been regarded as a low-cost substitute for platinum, and has fascinated researchers worldwide. Two crystalline phases of MoS 2 , i.e. the metallic octahedral 1T phase and semiconducting trigonal prismatic 2H phase, have been extensively analysed. In comparison to 2H-MoS 2 , the 1T phase exhibits enhanced and unique physicochemical properties. Designing a structure with two-dimensional mixed-phase MoS 2 , i.e. 1T/2H-MoS 2 nanosheets, via phase engineering for effective charge separation and migration has received growing interest in the field of photocatalytic hydrogen generation. In this study, by varying the wt% of ammonium bicarbonate via a facile hydrothermal technique, a series of 1T/2H-MoS 2 nanosheets have been fabricated. The presence of the corresponding elements, the electronic environment, phase purity, morphology and phase distinction were confirmed by Raman, XPS, XRD and HRTEM analyses. Additionally, the impedance data and the photocurrent density of the photocatalysts verify the efficient charge separation and transfer phenomenon. In accordance with the electrochemical measurements, the developed mixed-phase MoS 2 nanosheets exhibit a six times greater current density than 2H-MoS 2 . Furthermore, the highest response of photocatalytic hydrogen production is observed with the photocatalyst with 79% 1T phase, which is about 17 times greater than that of pristine 2H-MoS 2 due to the enrichment of active sites on both the edges and basal plane as well as the enhanced electronic conductivity due to the 1T phase. This study indicates that with the construction of a heterophase, i.e. 1T/2H-MoS 2 nanosheets, the photocatalytic hydrogen evolution capability can be boosted, providing new insights regarding these materials. Enhanced photocatalytic hydrogen evolution on 30-1T/2H-MoS 2 with a higher concentration of the 1T phase was achieved due to the higher availability of electrons and dense active sites after the incorporation of the 1T phase in 2H-MoS 2 .