Superior Electrocatalyst for All-pH Hydrogen Evolution Reaction : Heterogeneous Rh/N and S Co-Doped Carbon Yolk–Shell Nanospheres

Design of efficient and robust electrocatalysts for hydrogen evolution reaction (HER) under all pH conditions has attracted significant attention. In particular, it is still a considerable challenge since the HER kinetics of Pt in alkaline solutions is about two to three orders of magnitude lower than that in acidic conditions. Herein, a heterogeneous yolk–shell nanostructure with Rh nanoparticles embedded in S, N co-doped carbon nanospheres prepared by a facile self-template method is reported. The optimized electrocatalyst can achieve an extremely small overpotential of 13.5 mV at 10 mA cm^-2, low Tafel slope of 25.5 mV dec^-1, high turnover frequency of 0.143 s^-1 (at −75 mV vs. reversible hydrogen electrode), and long-term durability for 10 h, which is the record-high alkaline HER activity among the ever-reported noble metal based catalysts. These striking performances are ascribed to the optimized electronic structure and unique heterogeneous yolk–shell nanostructure. More importantly, it is also demonstrated that the obtained electrocatalyst exhibits superior activities in all pH range, which is better than commercial Pt/C and Rh/C catalysts. This work proves that Rh-based nanomaterials are promising superior electrocatalysts in a wide pH range and nanostructure design is a powerful tool to increase the mass/electron transfer during reaction.