Enhancing electrical conductivity of single-atom doped Co₃O₄ nanosheet arrays at grain boundary by phosphor doping strategy for efficient water splitting

High electrical conductivity guarantees a rapid electron transfer and thus plays an important role in electrocatalysis. In particular, for the single atom catalysts (SACs), to facilitate interaction between the single atom and supports, precisely engineering the conductivity represents a promising strategy to design SACs with high electrochemical efficiency. Here we show rhodium (Rh) SAC anchored on Co₃O₄ nanosheets arrays on nickel foam (NF), which is modified by a facile phosphorus (P-doped Rh SAC-Co₃O₄/NF), possessing an appropriate electronic structure and high conductivity for electrocatalytic reaction. With the introduction of P atom in the lattice, the electrocatalyst demonstrates outstanding alkaline oxygen evolution reaction (OER) activity with 50 mA·cm⁻² under overpotential of 268 mV, 6 times higher than that of Ir/C/NF. More interestingly, the P-doped Rh SAC-Co₃O₄/NF can get 50 mA·cm⁻² at only 1.77 V for overall water splitting. Both electrical conductivity studies and density functional theory (DFT) calculations reveal that the high conductivity at grain boundary improves the charge transfer efficiency of the Rh catalytic center. Furthermore, other noble-metal (Ir, Pd, and Ru) doped Co₃O₄ nanosheets arrays are prepared to exhibit the general efficacy of the phosphorus doping strategy.