Dual polarization in CoMoO4-NiMoO4 heterojunction boosted electrochemical charge storage

Binary transition metal oxides (BTMOs) stand out as a focal point due to their distinctive electrochemical properties. However, they encounter challenges like low conductivity and limited active sites. To tackle these obstacles, we have meticulously designed a CoMoO ₄-NiMoO ₄ (CMNM) heterostructure featuring significant compressive-tensile strain. This design facilitates the robust integration of CoMoO ₄ (CM) and NiMoO ₄ (NM), initiating interfacial polarization, and establishing a built-in electric field (BIEF) that significantly enhances electron transfer between the phases. Moreover, the strain serves as a driving force for the electric field, promoting the rearrangement of interface electrons and further boosting interfacial polarization. This avant-garde approach propels the CMNM electrode to achieve a remarkable specific capacity of 530.45 C g ⁻¹ at 1 A g ⁻¹, maintaining 327 C g ⁻¹ even at 10 A g ⁻¹, thus showcasing a superior rate capability. Furthermore, an asymmetric supercapacitor employing CMNM as the positive and FeOOH as the negative achieves a high energy density of 78.9 Wh kg ⁻¹ at a power density of 927.02 W kg ⁻¹. Our methodology, leveraging heterostructures coupled with the interfacial strain tactics, paves a novel avenue for high-performance supercapacitors.