2D/2D heterojunction interface: Engineering of 1T/2H MoS2 coupled with Ti3C2Tx heterostructured electrocatalysts for pH-universal hydrogen evolution

Abstract

Two-dimensional (2D) materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties. 2D molybdenum disulfide (MoS2) nanosheet has aroused considerable attention due to its tunable surface chemistry and high electrochemical surface area. Nonetheless, several shortcomings associated with MoS2, such as its naturally existing semiconducting 2H phase, which has limited active sites due to the inert basal plane, restrict its application in water electrocatalysis. Taking into account the benefits of the 1T/2H phase of MoS2, as well as the importance of engineering 2D/2D heterojunction interface for boosted electrocatalysis, metallic Ti3C2Tx was integrated with 1T/2H MoS2 to develop 2D/2D 1T/2H MoS2/Ti3C2Tx heterostructured nanocomposites. Herein, with only 25 % of the intercalating agent, 1T/2H MoS2 with the highest 1T phase content of ∼82 % was successfully synthesized. It was further incorporated with 1 wt% of Ti3C2Tx through a combination of ultrasonication and mechanical stirring process. The 1T/2H MoS2 (25D)/ Ti3C2Tx-1 (MTC-1) manifested outstanding electrocatalytic performance with an overpotential and Tafel slope of 280 mV (83.80 mV dec–1) and 300 mV (117.2 mV dec–1), for catalyzing acidic and alkaline medium HER, respectively. Pivotally, the as-prepared catalysts also illustrated long-term stability for more than 40 h. The coupling method for the 2D nanosheets is crucial to suppress the oxidation of Ti3C2Tx and the restacking issue of 2D nanosheets. The superior HER activity is ascribed to the synergistic effect between the heterostructure, enhancing the electronic structure and charge separation capability. The intrinsic property of the catalyst further confirms by turnover frequency (TOF) calculation. As such, this research paves the way for designing high-efficiency 2D electrocatalysts and sheds light on the further advancement of tunable 2D electrocatalysts for robust water splitting and beyond.