Hetero-structured noble metal-free high-entropy alloy CrFeCoNiCu/Mn-based oxide for highly efficient ORR/OER bifunctional catalysis

While bifunctional electrocatalysts enabling both oxygen reduction (ORR) and oxygen evolution (OER) reactions are recognized as pivotal chemical steps for next-generation energy devices, their practical implementation persists as a formidable scientific challenge. In this study, hetero-structured catalyst (CrFeCoNiCu/Mn 3 O 4 /MnO/NC) was successfully synthesized in situ containing both high-entropy alloy and spinel manganese-based oxide by a simple heat treatment process while two control samples (CrFeCoNiCu/Mn 3 O 4 /NC and CrFeCoNiCu/NC) were also prepared. It exhibited excellent catalytic performance and stability for both ORR and OER compared with commercial Pt/C and RuO 2 catalysts. The superior bifunctional performance was further observed with the overpotential gaps (ΔE gap ) of the three electrodes being 0.634 V, 0.655 V, and 0.698 V, respectively, which were lower than those of the combination of RuO 2 and Pt/C at 0.723 V. The enhanced catalytic performance was subsequently corroborated by density-functional theory (DFT). This study proposes an alternative method for the synthesis and design of high-performance bifunctional electrocatalysts.