文摘
An efficient and robust bifunctional electrocatalyst for both ORR and OER is highly desired for the applications in renewable energy technologies. Here, we prepare the carbonaceous microspheres (CMSs) by a facile hydrothermal treatment of glucose precursor and then dope the CMSs with La2O3, resulting in a high performance bifunctional electrocatalyst of La2O3@CMSs. In alkaline solution, the La2O3@CMSs catalyzes oxygen reduction reactions (ORR) with an onset potential of 0.80 V versus RHE and an overpotential only of 600 mV to achieve a current density of 1.3 mA cm鈥?. Meanwhile, oxygen evolution reaction (OER) at La2O3@CMSs electrode occurs at an onset potential of 1.60 V versus RHE and the overpotential is only 370 mV. Also, the as-prepared La2O3@CMSs exhibits high Faraday efficiency and long-term stability toward ORR and OER. Significantly, we demonstrate that La2O3@CMSs possesses surprisingly high mass activity, which is calculated to be 78.4 A g鈥? for ORR and 831.5 A g鈥? for OER, respectively. A potential window for ORR and OER at the modified electrode is estimated to be 0.80 V, implying a promising bifunctional electrocatalytical performance of La2O3@CMSs. The improvement of the bifunctional electrocatalytical activity may be due to the generation of active component of La鈥揙 and C鈥揙 at the surface and its synergistic interact with the La2O3@CMSs. This work not only provides a facile strategy for preparing highly efficient bifunctional electrocatalyst, but also offers an insight into the design of metal-oxides doped carbon materials for energy storage and conversion applications.