A durable and pH-universal self-standing MoC-Mo2C heterojunction electrode for efficient hydrogen evolution reaction

Efficient water electrolyzers are constrained by the lack of low-cost and earth-abundant hydrogen evolution reaction (HER) catalysts that can operate at industry-level conditions and be prepared with a facile process. Here we report a self-standing MoC-Mo2C catalytic electrode prepared via a one-step electro-carbiding approach using CO2 as the feedstock. The outstanding HER performances of the MoC-Mo2C electrode with low overpotentials at 500 mA cm(-2) in both acidic (256 mV) and alkaline electrolytes (292 mV), long-lasting lifetime of over 2400 h (100 d), and high-temperature performance (70 C-o) are due to the self-standing hydrophilic porous surface, intrinsic mechanical strength and self-grown MoC (001)-Mo2C (101) heterojunctions that have a Delta G(H*) value of -0.13 eV in acidic condition, and the energy barrier of 1.15 eV for water dissociation in alkaline solution. The preparation of a large electrode (3 cm x 11.5 cm) demonstrates the possibility of scaling up this process to prepare various carbide electrodes with rationally designed structures, tunable compositions, and favorable properties. Scalable fabrication of Low-cost hydrogen evolution reaction (HER) catalysts that can operate at industry-relevant conditions is highly needed for efficient water electrolyzers. Here the authors show a scalable synthesis of a MoC-Mo2C heterojunction electrode with efficient HER activity and high stability at industrial conditions.

Automated summary

The study presents a MoC-Mo2C catalytic electrode prepared using CO2, with excellent performance in both acidic and alkaline electrolytes, showing low overpotentials, long-lasting lifetime, and high-temperature performance. The self-standing hydrophilic porous surface, intrinsic mechanical strength, and self-grown MoC-Mo2C heterojunctions contribute to its outstanding hydrogen evolution reaction activity. Further, scalable fabrication of various carbide electrodes with rationally designed structures, tunable compositions, and favorable properties is demonstrated, highlighting the importance of efficient low-cost catalysts for water electrolyzers operating at industrial conditions.