Inkjet-printed MoS2-based 3D-structured electrocatalysts on Cu films for ultra-efficient hydrogen evolution reaction.

[Display omitted] • An all-in-one MoS 2 -based electrocatalyst for hydrogen evolution is constructed by inkjet printing. • Inkjet-printed 3D architecture contributes to the exposure of active catalytic sites. • 1T-MoS 2 surrounded by graphene reduces the charge-transfer impendence. • Cu contact supports the efficient electron injection from the electrode to catalytic materials. • The facile and scalable avenue allows the fabrication of electrocatalysts with high throughput. 2D transition metal dichalcogenides (TMDs) are emerging as promising alternative electrocatalysts for hydrogen evolution reaction (HER). However, key challenges are the limited density of available activity sites and poor electron accessibility. Herein, Cu film supported MoS 2 -based electrocatalyst with partial 1T phase and 3D architecture is constructed by inkjet printing. We aim to investigate if this configuration could provide largely exposed edge sites and enhance electron transfer for ultra-efficient hydrogen production. Towards this end, an ink containing few-layer MoS 2 nanosheets and reduced graphene oxide (RGO) is firstly prepared by liquid-phase exfoliation, in which semiconducting 2H-MoS 2 is partially transformed to metallic 1 T-MoS 2. We demonstrate that 1) nanosized few-layer MoS 2 spatially patterned by inkjet-printing provides sufficient active site exposure, 2) the 1T-MoS 2 and RGO conductive network reduce the charge-transfer impedance, and 3) the Cu support enhances the catalyst-electrode charge injection. Our all-in-one structure exhibits outstanding HER activities with low overpotential (51 mV at 10 mA cm−2 and 126 mV at 100 mA cm−2) and very low Tafel slope (32 mV dec-1). Also, the as-engineered electrode demonstrates ultrahigh cathodic current density. This work provides a facile, inexpensive, and scalable way for designing and fabricating TMDs-based electrocatalysts with excellent HER activity. [ABSTRACT FROM AUTHOR]