Single-Walled Carbon Nanotube Induced Optimized Electron Polarization of Rhodium Nanocrystals to Develop an Interface Catalyst for Highly Efficient Electrocatalysis

Carbon nanomaterials have been employed as crucial supports to increase surface loading and electronic conductivity. In addition, there are widely synergistic effects between the metallic species and the carbon supports for accelerated and stable electrocatalysis. In this work, a rhodium nanocrystal hybrid with single-walled carbon nanotubes (Rh/SWNTs) is reported to be an advanced catalyst for electrocatalytic reactions. SWNTs, as good electron acceptors, could modulate the electronic structure of Rh NPs and produce optimized electron polarization, which can give a high-performance interface catalyst. More eye catching are the excellent hydrogen evolution reaction (HER) properties in acid and alkali achieved by Rh/SWNTs with small overpotential (at 10 mA cm^-2) and Tafel slope (25 mV and 20 mV dec^-1 in 0.5 M H₂SO₄, 48 mV and 27 mV dec^-1 in 1.0 M KOH, respectively). Meanwhile, such electron polarization could also improve the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) properties. The Rh/SWNTs show high efficiency in overall water splitting and an integrated zinc-air battery with a low cell voltage of 1.59 V at 10 mA cm^-2 and a high open-circuit voltage of 1.42 V. This work highlights an electron polarization strategy on the interface between Rh and SWNTs to develop a high-performance multifunctional hydrogen and oxygen catalyst.