Tailoring the fusion effect of phase-engineered 1T/2H-MoS₂ towards photocatalytic hydrogen evolution

Abstract

Enhanced photocatalytic hydrogen evolution on 30-1T/2H-MoS2 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-MoS2.

Tailoring of 1T Phase-Domain MoS2 Active Sites with Bridging S22–/Apical S2– Phase-Selective Precursor Modulation for Enriched HER Kinetics

“…Besides, shifting of the peak belonging to the (002) plane from the 2θ value of 14.1 to 9.4° and arising of a novel peak at 18.4° corresponding to the (004) plane was noticed. This observation infers the rise of interlayer spacing owing to the intercalation of NH 4 + ions between the layers of MoS 2 since it is from the Mo precursor. ,,, …”

“…The XRD patterns of all the MoS 2 materials are almost identical, where it is very obvious that the peaks observed at the 2θ values of 9.3, 18.4, 32.5, 35.8, 43.0, and 57.3°are corresponding to the planes of (002), (004), (100), ( 102), (106), and (110), respectively. 13,27,39,40 Unlike 2H−MoS 2 , the shifting of the peak belonging to the (002) plane to a lower 2θ value (9.3°) and arising of a novel peak at 18.4°corresponding to the (004) plane has been noticed in all MoS 2 materials, which is mainly due to the rise of interlayer spacing owing to the intercalation of NH 4 + ions from the precursor (ATTM). 27,39 In addition, in the samples synthesized in the DMF solvents, that is, 1T-MoS 2 (DMF), 1T-MoS 2 (HyH+DMF), and 1T-MoS 2 (SBH +DMF), further extension of the (002) plane with higher intensity has been observed, which reveals the intercalation of DMF molecules along with the NH 4 + ions.…”

“…This observation infers the rise of interlayer spacing owing to the intercalation of NH 4 + ions between the layers of MoS 2 since it is from the Mo precursor. 13,31,39,40 Next, to inspect the influence of NH 4 + ions in phase selectivity, Raman spectral analysis was carried out and their spectrum is given in Figure S2 in Supporting Information. In the Raman spectrum, the peaks related to both 1T (J 1 , J 2 , and J 3 at 147.7, 236.5, and 336.0 cm −1 ) and 2H phase (E 1g , E 2g 1 , and A 1g at 282.1, 375.9, and 403.4 cm −1 ) are observed in the relatively equal intensity.…”

“…35,36,39 Even the external addition of ammonium salt (NH 4 OH or NH 4 X or NH 4 HCO 3 ) along with precursors (incapable to produce NH 4 + ions) was also done by the researchers to realize the advantage of NH 4 + ions in the formation of 1T-MoS 2 . 27,29,34,40 Moreover, ATTM is the only chemical that contains both Mo and S sources for the synthesis of MoS 2 . Although in ATTM Mo is in the oxidation state of Mo +6 , it is capable of undergoing intra-molecular auto-oxidation and concomitant reduction at S and Mo centers, respectively.…”

“…In a later stage, the importance of NH 4 + ions as an intercalant to raise the interlayer spacing and for the formation of 1T phase has been realized well. Hence, the precursors with the capability of producing NH 4 + ions have been intentionally used in the synthesis of MoS 2 to achieve the catalytically active 1T phase. ,, Even the external addition of ammonium salt (NH 4 OH or NH 4 X or NH 4 HCO 3 ) along with precursors (incapable to produce NH 4 + ions) was also done by the researchers to realize the advantage of NH 4 + ions in the formation of 1T-MoS 2 . ,,, …”