Precious metal-based catalysts exhibit superior performance over non-precious metal-based counterparts in acidic water splitting due to their relatively high corrosion resistance. However, their catalytic performance, especially in terms of mass activity and durability, is yet to be improved to meet commercial requirements. Herein, ultrathin porous Ir−Co−P alloy nanosheets (∼2.14 nm thick) with abundant grain boundaries, denoted as Ir−Co−P 340, were successfully synthesized via a KOH-assisted calcination and sequent phosphidation. The distinctive two-dimensional morphology exposes more surface atoms, shortens charge diffusion distances, and induces strong physical repulsion to prevent aggregation, while numerous pores facilitate efficient electrolyte penetration. The abundant grain boundaries not only proliferate active sites but also stabilize microstructures through a pinning effect. Dual alloying with Co and P enhances intrinsic catalytic activity and conductivity while reducing the cost of the catalyst. As a bifunctional catalyst in 0.5 M H2SO4 solution, Ir−Co−P 340 exhibited remarkable precious metal mass activities of 11.09 A mgIr−1 (HER, −0.03 Vvs.RHE) and 2.56 A mgIr−1 (OER, 1.26 Vvs.RHE), approximately 2.04 and 8.5 times higher than those of Pt/C and rutile-IrO2, respectively. A symmetric PEM electrolysis cell (Ir−Co−P 340||Ir−Co−P 340) delivered an ultralow cell voltage of 1.49 V at 10 mA cm−2 and outstanding durability over 200 h at a high current density of 50 mA cm−2.
Cao et al. (Fri,) studied this question.