Praseodymium and nickel co-doped Co3O4 enhances oxygen evolution reaction performance via interfacial water optimization and cobalt pre-oxidation for proton exchange membrane water electrolysis

Spinel Co 3 O 4 is theoretically predicted as a promising cost-effective anodic electrocatalyst for proton exchange membrane water electrolysis (PEMWE) owing to favorable adsorption energetics. However, the inevitable surface reconstruction under operating conditions severely compromises its long-term activity and stability. Here we report a praseodymium (Pr) and nickel (Ni) co-doped cobalt spinel (PrNi-Co 3 O 4 ) catalyst featuring a spatially selective distribution of uniform bulk Ni doping and spontaneous surface Pr segregation, which realizes a surface-interface synergistic optimization strategy to effectively overcome this bottleneck. Density functional theory calculations and voltammetric investigations reveal that the nickel dopants induce surface pre-oxidation, boosting intrinsic activity while simultaneously increasing the energy for lattice cobalt leaching. Besides, in-situ surface-enhanced infrared absorption spectroscopy demonstrates that surface praseodymium species lowers the water dissociation barrier by decreasing the hydrogen bonding degree, while simultaneously reinforcing stability through the mitigation of metal-oxygen bond polarization and the anchoring of oxygenated intermediates. The assembled PEMWE cell employing the PrNi-Co 3 O 4 anode operates at only 2.02 V at 1 A cm −2 and sustains stable operation for 490 h, placing it at the forefront of reported non-noble metal catalysts. This study helps advance the commercial viability and scalability of green hydrogen production by circumventing the reliance on precious iridium.