Small difference in the work function induced superior catalytic performance of MoS2/M2CO2 heterostructures for hydrogen evolution reaction: A computational study

Motivated by the unique structures and diverse properties of two-dimensional (2D) heterostructures, herein, we designed a series of heterojunction-based catalysts composed of MoS2 and M2CO2 monolayers (M = Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta) monolayers, and investigated their activities towards HER by means of density functional theory (DFT) computations. The results showed that these van der Waals heterostructures exhibit favorable stability, high stiffness, and versatile electronic properties. Interestingly, MoS2/Nb2CO2 and MoS2/Ta2CO2 candidates were expected to exhibit high HER catalytic activity at low H coverage due to their optimal H* adsorption strength, and the low barrier for H2 release via the Heyrovsky mechanism. More importantly, we for the first time proposed that the difference in the work functions between MoS2 and M2CO2 can be utilized as an ideal descriptor to rationalize the remarkably different HER catalytic activity of these MoS2/M2CO2 hybrid materials. This work not only suggested efficient catalysts for advancing sustainable H2 production, but also opened a new door to further explore the potential of 2D heterostructures in electrocatalysis.