The lack of highly efficient, durable, and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) working at high current densities poses a significant challenge for the large-scale implementation of hydrogen production from renewable energy. Herein, amorphous molybdenum tungsten sulfide/nitrogen-doped reduced graphene oxide nanocomposites (a-MoWSx /N-RGO) are synthesized by plasma treatment for use as high-performance HER catalysts. By adjusting the plasma treatment duration and chemical composition, an optimal a-MoWSx /N-RGO catalyst is obtained, which exhibits a low overpotential of 348 mV at a current density of 1000 mA cm-2 and almost no decay after 24 h of working at this current density, outperforming commercial platinum/carbon (Pt/C) and previously reported heteroatom-doped MoS2 -based catalysts. Based on density functional theory (DFT) calculations, it is found that with a reasonable tungsten doping level, the catalytic active site (2S2 - ) shows excellent catalytic performance working at high current densities because extra electrons preferentially fill at 2S2 - . The introduction of tungsten tends to lower the electronic structure energy, resulting in a closer-to-zero positive . Excessive tungsten introduction, however, can lead to structural damage and a worse HER performance under high current densities. The work provides a route towards rationally designing high-performance catalysts for the HER at industrial-level currents using earth-abundant elements.
Keywords: amorphous molybdenum tungsten sulfide; amorphous transition-metal sulfides; density functional theory; high current density; hydrogen evolution reaction; plasma treatment.
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