Enhancing oxygen and hydrogen evolution activities of perovskite oxide LaCoO3 via effective doping of platinum

摘要

In this study, a series of perovskite oxides LaCo _(1? x ) Pt _( x ) O _(3? δ ) ( x = 0, 0.02, 0.04, 0.06, and 0.08) were prepared by the citric acid–ethylenediaminetetraacetic acid (CA–EDTA) complexing sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then, the samples were investigated as OER and HER bifunctional electrocatalysts in alkaline media. Compared with other catalysts, LaCo _(0.94) Pt _(0.06) O _(3? δ ) had good stability and presented more activity at a lower overpotential of 454 mV (at 10 mA cm ~(?2) ), a lower Tafel slope value of 86 mV dec ~(?1) and a higher mass activity of 44.4 A g ~(?1) for OER; it displayed a lower overpotential of 294 mV (at ?10 mA cm ~(?2) ), a lower Tafel slope value of 148 mV dec ~(?1) and a higher mass activity of ?34.5 A g ~(?1) for HER. The improved performance might depend on a larger ECSA, faster charge transfer rate and higher ratio of the highly oxidative oxygen species (O _(2) ~(2?) /O ~(?) ). Furthermore, the e _(g) orbital filling of Co approaching 1.2 in the B site might play a leading role.