Rational Regulation of High-Entropy Perovskite Oxides through Hole Doping for Efficient Oxygen Electrocatalysis
Gaoliang Fu, Ruipeng Hou, Li Sun, Huili Liu, Yaru Wei, Ruixue Wei, Xiangyu Meng, Shouren Zhang, Baocheng Yang
Abstract
Due to the high configuration entropy, unique atomic arrangement, and electronic structures, high-entropy materials are being actively pursued as bifunctional catalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc–air batteries (ZABs). However, a relevant strategy to enhance the catalytic activity of high-entropy materials is still lacking. Herein, a hole doping strategy has been employed to enable the high-entropy perovskite La(Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 to effectively catalyze the ORR and OER. Hole doping experiments rely on the substitution of Sr 2+ for La 3+ . The optimized La 0.7 Sr 0.3 (Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 displays remarkable activity for the ORR and the OER, with a low potential difference of 0.880 V between the half-wave potential of the ORR and the OER potential at 10 mA cm –2, exceeding the majority of perovskite bifunctional catalysts. Further analysis of the electronic structures reveals that hole doping could regulate the e g -orbital filling of the transition-metal cations in high-entropy perovskites to an ideal position and thereby generate many highly active sites to promote the redox activity of oxygen. The assembled rechargeable ZAB with the targeted high-entropy perovskite as the cathode affords a specific capacity of 774.5 mAh g Zn –1 under 10 mA cm –2 and durability for a period of 300 cycles, comparable to that of the 20%Pt/C + RuO 2 ZAB. This work offers an important approach for the advancement of efficient high-entropy perovskites for ZABs.