Highly clean and efficient iron phosphates modified by Ru nanocrystals for water oxidation

Optimizing the architecture of non-polluting, highly efficient, robust, and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is extremely crucial for accelerating the application of water splitting. Herein, a highly green and active OER electrocatalyst composed of Ru nanocrystal modified iron-rich phosphates is successfully developed via a hydrothermal and post-annealing approach. The eco-friendly phosphorus source of lecithin is employed to fabricate transition metal phosphates for the first time, which avoids the use of toxic and dangerous phosphorus sources. Meanwhile, it is found that Ru nanocrystals could form heterostructures with iron phosphates and induce conversion to iron-rich phosphates, which would greatly enhance the conductivity of the substrate and elevate the catalytic activity. As a result, overpotentials of only 250 mV and 290 mV are required to deliver 10 and 100 mA cm^-2 using this typical electrocatalyst. Also, the j-t curve shows no distinct variations in current over 45 h at a constant overpotential of 334 mV, indicating the outstanding activity and durability of the catalyst. Furthermore, nickel/cobalt-rich phosphates and phosphides were also acquired using similar experimental procedures, manifesting the wide applicability of Ru actuation. Hence, this work offers a convenient and scalable method for designing highly efficient, green, clean, and cost-effective electrocatalysts for water splitting.