Constructing multilevel structure with microdomains of oxides on Three-Dimensional High-Entropy alloy support toward efficient oxygen evolution

The MnCr2O4 microdomains self-precipitating out from solid solution during reducing treatment can change the local coordination environment of the densely oxygen micro-alloying HEA matrix and reconstruct its surface, which is benefit for enhancing charge transfer efficient, modulating the adsorption energy and increasing the electro-active sites for OER process. [Display omitted] •A large-scaled dual-phase MnCr2O4@O-HEA electrode is prepared by modified metallurgy approach.•The precipitation of MnCr2O4 from O-HEA induces lattice shrinking and surface reconstruction of HEA.•The multilevel structure exhibits fast charge transportation and multiple catalytically active sites.•The O-HEA2 sample exhibits impressive oxygen evolution properties. High-entropy alloy (HEA) with maximized configurational entropy has shown a great promise for anodic water splitting, but still limited to their unsatisfactory configuration and large-scaled application. In the present study, a series of dual-phase electrodes with spinel MnCr2O4 microdomains pinning on large-scaled and flexible surface oxidized high-entropy alloys (O-HEA) as highly efficient electrocatalysts is prepared by combining modified non-solvent induced phase separation (NIPs) and metallurgy approaches. The precipitation of MnCr2O4 microdomains from HEA support not only result in a shrinking of lattice constant, but also lead to a surface reconstruction. Besides, the MnCr2O4 microdomains can synergy with reconstructed O-HEA support to increase the hydrophilic property and provide high-efficient electron/ion transport, thus promoting the oxygen evolution performance. By virtues of the multilevel structure, the O-HEA2 electrode exhibits impressive OER properties with a low overpotential of 268 mV and Tafel slope of 51.6 mV dec−1 in 1 M KOH at 10 mA cm−2. It also exhibits a long durability exceed 70 h at 25 mA cm−2. This work provides a new prospect for the rational design of large-scaled and self-supported 3D HEA based electrodes for energy conversion applications.