CO₂-Induced Phase Engineering: Protocol for Enhanced Photoelectrocatalytic Performance of 2D MoS₂ Nanosheets

Abstract

Molybdenum disulfide (MoS2) is a promising non-precious-metal catalyst, but its performance is limited by the density of active sites and poor electrical transport. Its metallic 1T phase possesses higher photoelectrocatalytic activity. Thus, how to efficiently increase the concentration of the 1T phase in the exfoliated two-dimensiaonal (2D) MoS2 nanosheets is an important premise. In this work, we propose a strategy to prepare a 2D heterostructure of MoS2 nanosheets using supercritical CO2-induced phase engineering to form metallic 1T-MoS2. Theoretical calculations and experimental results demonstrate that the introduced CO2 in the 2H-MoS2 host can prompt the transformation of partial 2H-MoS2 lattices into 1T-MoS2. Moreover, the electrical coupling and synergistic effect between 2H and 1T phases can greatly facilitate the efficient electron transfer from the active sites of MoS2, which significantly improves the photocatalytic performance.

Two-Dimensional Material Molybdenum Disulfides as Electrocatalysts for Hydrogen Evolution

“…Therefore, strategies that can increase the electrons' hopping efficiency in the vertical direction or lower the resistance are expected to be able to enhance the electrocatalytic performance of MoS 2 materials. [79]. Reproduced from [76,79] with permission from copyright American Chemical Society and [78] with permission from copyright 2016 The Royal Society of Chemistry.…”

“…[79]. Reproduced from [76,79] with permission from copyright American Chemical Society and [78] with permission from copyright 2016 The Royal Society of Chemistry.…”

“…Fabricating TMDs/metal heterostructures is an effective way to further enhance their light absorption due to an increase in the local density of states (LDOS) near the semiconductor/metal interface [79][80][81]. The high light absorption combined with the active electrocatalytic performance make the semiconducting TMDs an excellent photoelectrocatalyst [78][79][80][81]. Lewis's group investigated the photoelectrochemical performance of Pt-decorated p-type WSe2 photocathodes by using scanning photocurrent microscopy [78].…”

“…The linear sweep voltammograms indicated that the photocurrent increased markedly when the laser beam was irradiated on the Pt-decorated p-type WSe2 photocathodes (Figure 9c). For the MoS2, the metallic 1T phase possesses higher photoelectrocatalytic activity because it can serve as a good electron acceptor and transporter material [79]. Faster electron transport can effectively suppress the recombination processes of photogenerated charges and thus enhance photocatalytic activity under visible light.…”

“…As expected, the photocurrent of 1T@2H MoS2-based photoelectrochemical cells (Figure 9d) at −0.6 V was −1400 µA/cm 2 , much higher than that of pure 2H MoS2 (−400 µA/cm 2 ). [79]. Reproduced from [76,79] with permission from copyright American Chemical Society and [78] with permission from copyright 2016 The Royal Society of Chemistry.…”