Electrodepositing Ru on carbon cloth supported Co(OH)2 nanosheet array for active overall water electrolysis

Exploring bifunctional electrocatalysts with high activity for practical overall water splitting is urgent but challenging. Boosting low-cost catalysts with trace amount of noble metals supplies a promising scheme. Herein, Ru nanoparticles decorated Co(OH)2 nanosheet array on carbon cloth substrate (Ru-Co(OH)2/CC) is prepared via a two-step electrodeposition strategy. Trace Ru in the sample activates the bifunctionality of Co(OH)2 in alkaline media. For oxygen evolution, the synergism between Ru and Co(OH)2 can generate abundant oxygen vacancies for much improved catalysis activity, achieving low overpotential of 203 mV at 10 mA cm−2. For hydrogen evolution, Ru endows Co(OH)2 with Pt-like catalysis activity, for instance, the exchange current density of 1.32 mA cm−2 for Ru-Co(OH)2/CC that is comparable to that of Pt/C (1.44 mA cm−2), as well as low overpotential of 55 mV at 10 mA cm−2 that is close to that of Pt/C (35 mV). The excellent bifunctionality is demonstrated in a Ru-Co(OH)2/CC constructed two-electrode configuration. The robust catalytic activity (cell voltage of 1.54 V at 10 mA cm−2) with high durability of 60 h is obtained for overall water splitting. Moreover, a single AAA battery can drive the sustainable overall water splitting in such a cell.