Magnetron Sputter-Coated Nanoparticle MoS2 Supported on Nanocarbon: A Highly Efficient Electrocatalyst toward the Hydrogen Evolution Reaction (original) (raw)

The design and fabrication of inexpensive highly efficient electrocatalysts for the production of hydrogen via the hydrogen evolution reaction (HER) underpin a plethora of emerging clean energy technologies. Herein, we report the fabrication of highly efficient electrocatalysts for the HER based on magnetron-sputtered MoS 2 onto a nanocarbon support, termed MoS 2 /C. Magnetron sputtering time is explored as a function of its physiochemical composition and HER performance; increased sputtering times give rise to materials with differing compositions, i.e., Mo 4+ to Mo 6+ and associated S anions (sulfide, elemental, and sulfate), and improved HER outputs. An optimized sputtering time of 45 min was used to fabricate the MoS 2 /C material. This gave rise to an optimal HER performance with regard to its HER onset potential, achievable current, and Tafel value, which were −0.44 (vs saturated calomel electrode (SCE)), −1.45 mV s −1 , and 43 mV dec −1 , respectively, which has the highest composition of Mo 4+ and sulfide (MoS 2). Electrochemical testing toward the HER via drop casting MoS 2 /C upon screen-printed electrodes (SPEs) to electrically wire the nanomaterial is found to be mass coverage dependent, where the current density increases up to a critical mass (ca. 50 μg cm −2), after which a plateau is observed. To allow for a translation of the bespoke fabricated MoS 2 /C from laboratory to new industrial applications, MoS 2 /C was incorporated into the bulk ink utilized in the fabrication of SPEs (denoted as MoS 2 /C-SPE), thus allowing for improved electrical wiring to the MoS 2 /C and resulting in the production of scalable and reproducible electrocatalytic platforms. The MoS 2 /C-SPEs displayed far greater HER catalysis with a 450 mV reduction in the HER onset potential and a 1.70 mA cm −2 increase in the achievable current density (recorded at −0.75 V (vs SCE)), compared to a bare/unmodified graphitic SPE. The approach of using magnetron sputtering to modify carbon with MoS 2 facilitates the production of mass-producible, stable, and effective electrode materials for possible use in electrolyzers, which are cost competitive to Pt and mitigate the need to use timeconsuming and low-yield exfoliation techniques typically used to fabricate pristine MoS 2 .