Self-assembly of homointerface engineered IrCo0.14 bracelet-like nanorings as efficient and stable bifunctional catalysts for electrochemical water splitting in acidic media

To develop robust and highly active bifunctional electrocatalysts for electrochemical water splitting in acidic media is still a great challenge for proton exchange membrane (PEM) electrolyzer. Herein, a self-assembled IrCox nanorings (NRs) with bracelet-like architecture is fabricated as a bifunctional high-efficient overall water splitting electrocatalyst by a facile, controllable and surfactant-free strategy. The unique nanoring architecture enriches in abundant homointerface and strong synergistic electronic interaction between Ir and Co. The optimized IrCo0.14 NRs exhibits remarkable electrocatalytic performance with a low overpotential of 16 mV for hydrogen evolution reaction (HER) and 278 mV for oxygen evolution reaction (OER) at 10 mA cm−2 in 0.1 M HClO4, respectively, significantly outperforming the commercial Pt/C, Ir/C and reported Ir-based catalysts. As both anode and cathode, a cell voltage of only 1.53 V to reach 10 mA cm−2 is obtained for overall water splitting and no obvious activity loses after a long-term electrolysis for 14 h. Combined with a PV cell, this catalyst also shows excellent water splitting performance with a solar-to-hydrogen conversion efficiency of 12.8%. This work provides further insights on designing promising and efficient bifunctional electrocatalysts for clean energy electrochemical conversion in the future. [Display omitted] •Bracelet-like IrCox nanorings (NRs) assembled by alloy nanoparticles are fabricated.•The homointerface and alloy effects of IrCox NRs boost the catalytic performance.•IrCo0.14 NR catalyst exhibits superior HER and OER performance in acidic media.•IrCo0.14 NR enables stable water splitting in acidic media for 14 h at 10 mA cm−2.•IrCo0.14 NR also exhibits excellent solar-driven overall water splitting performance.