Non-platinum-based electrocatalysts for high performance acidic hydrogen evolution reactions in proton exchange membrane water electrolysis

To replace Pt for economical and scalable H 2 O to H 2 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 Mo 2.8 -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 Mo 2.8 -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 Mo 2.8 -Ru@CNT- 2.8 . Specially, the optimized Mo 2.8 -Ru@CNT- 2.8 catalyst represent an advance in mass activity (4.4 A mg −1 Ru ) compared to commercial Pt/C catalysts (3.1 A mg −1 Ru ) and high per-site activity (32.7 s −1 ) under acidic conditions while remaining the excellent stability. At the same time, Mo 2.8 -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 mg Ru 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 mg Pt cm −2 (1.74 V up to 1 A cm −2 ), and maintains long-term stability for 700 h at 1 A cm −2 . • Bimetallic nanoparticles combining SMSI and size effects. • The optimal H* adsorption energy and binding energy between Ru-Ru/Ru-Mo can be obtained by adjusting the particle size. • The introduction of Mo and the SMSI effect improve stability. • [email protected] exhibits outstanding HER performance in PEM.