Abstract
To replace Pt for economical and scalable H2O to H2 conversion in proton exchange membranes (PEM) water electrolysis, efforts are being made to find cost-effective catalysts that delicately co-ordinate key parameters such as high mass activity and long durability. We found that by engineering the small size (<5 nm) of RuMo bimetallic nanoparticles (NPs) on carbon nanotube (CNT) with a strong metal-support interaction (SMSI) effect, we could obtain Mo2.8-Ru@CNT-2.8 catalysts with optimal activity and stability in acidic HER (Mo amount is 2.8 wt% and NPs size is about 2.8 nm). Experimental and theoretical studies reveal that reducing the size to about 2.8 nm can simultaneously obtain the optimal Gibbs free energy of H intermediate adsorption and the bonding energy between Ru-Ru/Ru-Mo, which contribute to the improvement of the catalytic activity and stability of Mo2.8-Ru@CNT-2.8. In addition, Mo doping can greatly increase the formation energy of Ru vacancies, which contribute to the improvement of the catalytic stability of Mo2.8-Ru@CNT-2.8. Specially, the optimized Mo2.8-Ru@CNT-2.8 catalyst represent an advance in mass activity (4.4 A mg−1Ru) compared to commercial Pt/C catalysts (3.1 A mg−1Ru) and high per-site activity (32.7 s−1) under acidic conditions while remaining the excellent stability. At the same time, Mo2.8-Ru@CNT-2.8 as a cathode in the proton exchange membrane (PEM) water electrolyser exhibits excellent cell voltages with a Ru loading of 0.06 mgRu cm−2 (1.7 V to 1 A cm−2), 0.12 times that of commercial Pt/C with a Pt loading of 0.5 mgPt cm−2 (1.74 V up to 1 A cm−2), and maintains long-term stability for 700 h at 1 A cm−2.
Published Version
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