Gradient porous electrode with high mass loading derived by ultrafast self-combustion for supercapacitor and oxygen evolution reaction

Abstract

Robustly coupling high mass loading with bi-continuous porous architecture is highly desirable for high-property energy storage devices and electrocatalysts. Herein, we report that a gradient porous hybrid electrode is highly efficient for aqueous supercapacitor and alkaline electrocatalyst applications. The heterostructured NixCoyMn1-x-yO and Mn3O4 oxides (GHPO) with ultrahigh mass loading (>8 mg cm−2) was in situ grown on gradient porous alloy precursors by a fast self-combustion method. The gradient architecture with aligned transport channels outside and bi-continuous pores inside can synergy with heterointerfaces and hydrophilic nature to realize optimal local charge and mass transport dynamics inside the thick electrode, thus accelerates electrochemical reaction kinetics. Consequently, the GHPO3 electrode achieves high areal capacitances of 4.0 and 2.6 F cm−2 at 10 and 50 mA cm−2, and maintains a superior cyclic stability. The assembled symmetric supercapacitor delivers high capacitance of 0.46 F cm−2 and a considerable energy density of 0.13 mWh cm−2. Meanwhile, the GHPO3 sample obtains low overpotentials of 340 mV to reach 10 mA cm−2 during oxygen evolution reaction process. This study on gradient architecture design with high mass-loading brings perspectives in high-energy density batteries and high-performance electrocatalysts.