Synergistic Interfacial Effect of Ru/Co 3 O 4 Heterojunctions for Boosting Overall Water Splitting.

Low-cost bifunctional electrocatalysts capable of efficiently driving the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are needed for the growth of a green hydrogen economy. Herein, a Ru/Co 3 O 4 heterojunction catalyst rich in oxygen vacancies (V O ) and supported on carbon cloth (RCO-V O @CC) is prepared via a solid phase reaction (SPR) strategy. A RuO 2 /Co 9 S 8 @CC precursor (ROC@CC) is first prepared by loading Co 9 S 8 nanosheets onto CC, following the addition of RuO 2 nanoparticles (NPs). After the SPR process in an Ar atmosphere, Ru/Co 3 O 4 heterojunctions with abundant V O are formed on the CC. The compositionally optimized RCO-V O @CC electrocatalyst with a Ru content of 0.55 wt.% exhibits very low overpotential values of 11 and 253 mV at 10 mA cm -2 for HER and OER, respectively, in 1 m KOH. Further, a low cell voltage of only 1.49 V is required to achieve a current density of 10 mA cm -2 . Density functional theoretical calculations verify that the outstanding bifunctional electrocatalytic performance originates from synergistic charge transfer between Ru metal and V O -rich Co 3 O 4 . This work reports a novel approach toward a high-efficiency HER/OER electrocatalyst for energy storage and conversion.