High‐performance Te‐doped Co 3 O 4 nanocatalysts for oxygen evolution reaction

To reduce the overpotential of electrocatalytic oxygen evolution reaction (OER) for high-efficiency water splitting, a series of 2 to 5 nm ultrafine spinel Co3O4 nanoparticles (NPs) with varied amount of lattice-doped Te (XTe-Co3O4, X represents the nominal molar ratio Te/Co of 0, 2, 4, 6, 8%) as catalysts were prepared through a simple hydrothermal synthesis method. The 6%Te-Co3O4 catalyst was optimized to obtain the overpotential as low as 313 mV at 10 mA cm−2, a small Tafel slope of 75 mV dec−1 in 1 M KOH for OER, outperforming this series and many reported Co3O4-based catalysts. Te doping introduced lattice distortion and resulted in smaller size of Te-Co3O4 NPs with enlarged surface area for more accessible active sites. Oxygen vacancies were created to modify the electronic structure, improve the active sites density, and decrease the kinetic energy barriers of XTe-Co3O4. The electronic conductivity of 6%Te-Co3O4 was improved to accelerate the charge transfer efficiency. All these effects contributed to promoting the reaction kinetics and minimizing the OER overpotentials for high-performance electrocatalysis.