A high-entropy and low-cobalt perovskite of La0.7Sr0.3Co0.2Mn0.2Ni0.2Fe0.2Al0.2O3-x for both oxygen evolution and methanol oxidation reactions

The cobalt (Co)-based perovskites as the promising oxygen evolution reaction (OER) catalysts have gained the significant attentions owing to their exceptional intrinsic catalytic activity. However, the major B-site element of Co in these perovskites is high cost and scarcity, which seriously limits their large-scale applications. In this work, we synthesize a high-entropy perovskite (HEP) with the low Co content and high OER catalytic activity. Also, the OER catalytic performances of the perovskites with the different B-site configurational entropies and compositions are systematically investigated. The optimized HEP with the composition of La0.7Sr0.3Co0.2Mn0.2Ni0.2Fe0.2Al0.2O3-x (L5) exhibits the outstanding OER activity with a low overpotential of 339 mV at 10 mA cm−2. Furthermore, no degradation of L5 is observed during long-term OER stability test for 100 h. Interestingly, L5 also shows the superior catalytic activity toward the methanol oxidation reaction (MOR). During the MOR catalytic process, a low overpotential of 219 mV can be achieved at 10 mA cm−2, and the value-added product of formate with the selectivity of ∼70% can be simultaneously obtained. The excellent OER and MOR performances of L5 can be related to the synergistic effects of the major B-site components and configuration entropy effect of HEPs. Our work proposes a promising high-entropy strategy to reduce the Co content in the Co-based perovskites as well as enhance their electrocatalytic activities.