Unique multi-mode nanoporous CoCrFeNiAl high entropy alloy for hydrogen peroxide sensor

•The self-supporting hierarchical nanoporous CoCrFeNiAl1.5 high entropy alloy ribbons were prepared by one step phase dealloying.•Unique hierarchical nanoporous structure possess high specific surface area and provide reaction channels for the transport of reactant molecule and ions.•The Co, Cr, Fe oxides in fine nanopores forming as reactive center provide sufficient active sites for the reduction reaction of H2O2 molecules.•NPCCF-1.5 with visible Fe-Cr GB increase H2O2 molecule diffusion coefficient and speed electron transfer, which is benefit to accelerate reactant process. High entropy alloys (HEAs) are promising materials in electrocatalytic fields due to inherent compositional designability and structural diversity. Herein, unique hierarchical CoCrFeNiAl1.5 high entropy nanoporous structure (NPCCF-1.5) with two-level pores of ∼580 nm and ∼13 nm in size, and visible inherited Fe-Cr(Co) rich disordered BCC phase grain boundary (Fe-Cr(Co) GB) was constructed from CoCrFeNiAl1.5 HEA ribbons by preferential dissolution of the Al-Ni rich ordered BCC phase (B2). The self-supporting NPCCF-1.5 electrodes as H2O2 sensor exhibit an ultra-high sensitivity of 510.4 μA mM-1 cm-2, a wide linear detection range up to 49.95 mM and low limit of quantitation of 4 μM (S/N ≥ 3), along with excellent anti-interference ability. The hierarchical nanoporous structure supports mass transferring channels and large amounts of active sites for catalytic reaction, and inherited Fe-Cr(Co) GB facilitates reactive molecule/electron transfer to the active sites of the fine pores composed of Co, Cr, and Fe oxides. The strategy that utilizes the inherited microstructural advantage of HEAs provides a reliable route for the development of low-cost, high-performance porous electrocatalysts. [Display omitted]