Engineering Two-Dimensional Mass-Transport Channels of the MoS Nanocatalyst toward Improved Hydrogen Evolution Performance.

In addition to the intrinsic catalytic activity, the mass transport should be taken into adequate account in order to realize the superior performance of electrocatalysts. Here, we engineer the interstitial space between MoS nanosheets via the introduction of "spacers" to construct two-dimensional (2D) channels for favorable mass transport. The nano-sized spacers effectively separate MoS nanosheets, generating open and connective channels to fulfill timely reactant supply and rapid gas release. Besides, the spacer served as the physical support can prevent the collapse of 2D channels. Because of the engineering of nanostructured channels, a reduction in overpotential by approximately 100 and 360 mV at -10 and -100 mA cm, respectively, a decrease in the Tafel slope from 66.7 to 39.4 mV dec, and a more stable operation can be achieved. After being integrated by carbon paper, a further improved performance of 198 mV at -200 mA cm and 36 mV dec can be obtained. This work emphasizes the importance of mass-transport channels and paves a way to enhance the hydrogen evolution reaction performance.