Robust tuning metal/carbon heterointerfaces via ketonic oxygen enables hydrogen evolution reaction outperforming Pt/C

Large-scale synthesis of metal/carbon hybrids with tunable metal/carbon heterointerfaces is vital for practical application of such hybrids in electrocatalysis. Herein, we developed a facile route for large-scale crafting of ultrafine Ru nanoparticles (NPs) anchored on the ketonic C=O groups of carbon nanotubes (CNTs) (9.6 g in one batch). From both experimental results and theoretical calculations, we demonstrate that C=O (rather than C-O) groups can be exploited to engineer the heterointerface of CNTs and Ru NPs. In fact, the electronic structure of Ru becomes considerably improved because the high polarity of C=O facilitates the interface electron transfer of Ru/CNTs. Consequently, the obtained Ru-O-CNTs hybrids with low Ru loading of 1.5 wt% display a small overpotential of 25 mV at 10 mA cm(-2) and with fast kinetics as deduced from a small Tafel slope of 20.4 mV dec(-1) for hydrogen evolution reaction (HER) in 1 M KOH. Impressively, at 70 mV overpotential, the hybrids exhibit a record mass activity of 20.4 mA mu g(Ru)(-1) , which is more than 50-fold of that for commercial Pt/C. Therefore, for the first time, we identified the vital role of C=O groups for engineering metal/carbon heterointerfaces towards robust and efficient electrocatalysis.