Synthesis of phosphorus-iridium nanocrystals and their superior electrocatalytic activity for oxygen evolution reaction

We here demonstrate a high efficient phosphorus-iridium (P-Ir) electrocatalyst for oxygen evolution reaction (OER). The P-Ir particles show an atomic ratio of 2:1 (P:Ir) and a highly uniform size of 1.8-3.6 nm (>90%). Compared to the Ir nanoparticles, the present P-Ir catalyst displays higher catalytic activities in acidic, alkaline, and neutral solutions. The P-Ir catalyst only requires an onset-potential of 190 mV for oxygen evolution in the solution of 0.1M HClO4. Compared with Ir catalyst, the P-Ir reduces the overpotential similar to 30 mV to achieve the oxygen-evolution current densities of 10 and 30 mA cm(-2), respectively. Additionally, at an overpotential of 266 mV, P-Ir obtains a mass activity 1.7 times higher than Ir. Importantly, the P-Ir catalyst shows ultrahigh stability in acidic condition. The enhancement in electrocatalysis should be ascribed to the phosphorus introduction. The work demonstrates that the present P-Ir nanocrystals are promising catalysts in electrochemical splitting water in a broad pH range.