Tensile Strain-Mediated Spinel Ferrites Enable Superior Oxygen Evolution Activity
Yaotian Yan, Jinghuang Lin, Keke Huang, Xiaohang Zheng, Liang Qiao, Shude Liu, Jian Cao, Seong Chan Jun, Yusuke Yamauchi, Junlei Qi
Abstract
Exploring efficient strategies to overcome the performance constraints of oxygen evolution reaction (OER) electrocatalysts is vital for electrocatalytic applications such as H 2 O splitting, CO 2 reduction, N 2 reduction, etc . Herein, tunable, wide-range strain engineering of spinel oxides, such as NiFe 2 O 4, is proposed to enhance the OER activity. The lattice strain is regulated by interfacial thermal mismatch during the bonding process between thermally expanding NiFe 2 O 4 nanoparticles and the nonexpanding carbon fiber substrate. The tensile lattice strain causes energy bands to flatten near the Fermi level, lowering e g orbital occupancy, effectively increasing the number of electronic states near the Fermi level, and reducing the pseudoenergy gap. Consequently, the energy barrier of the rate-determining step for strained NiFe 2 O 4 is reduced, achieving a low overpotential of 180 mV at 10 mA/cm 2 . A total water decomposition voltage range of 1.52–1.56 V at 10 mA/cm 2 (without iR correction) was achieved in an asymmetric alkaline electrolytic cell with strained NiFe 2 O 4 nanoparticles, and its robust stability was verified with a voltage retention of approximately 99.4% after 100 h. Furthermore, the current work demonstrates the universality of tuning OER performance with other spinel ferrite systems, including cobalt, manganese, and zinc ferrites.