Crystalline–amorphous biphasic ZnMnO₃ was photodeposited by a one-step, room-temperature process from an aqueous precursor solution onto ZnO nanowires. The specific morphology of the photodeposit and its homogeneous dispersion at the nanowire surface give rise to an electrode architecture, where ZnMnO₃ shells act as an electroactive, pseudocapacitive phase in aqueous electrolytes.

Abstract

Compositionally and structurally complex semiconductor oxide nanostructures gain importance in many energy-related applications. Simple and robust synthesis routes ideally complying with the principles of modern green chemistry are therefore urgently needed. Here we report on the one-step, room-temperature synthesis of a crystalline–amorphous biphasic ternary metal oxide at the ZnO surface using aqueous precursor solutions. More specifically, conformal and porous ZnMnO₃ shells are photodeposited from KMnO₄ solution onto immobilized ZnO nanowires acting not only as the substrate but also as the Zn precursor. This water-based, low temperature process yields ZnMnO₃/ZnO composite electrodes featuring in 1 M Na₂SO₄ aqueous solution capacitance values of 80–160 F g⁻¹ (as referred to the total mass of the porous film i. e. the electroactive ZnMnO₃ phase and the ZnO nanowire array). Our results highlight the suitability of photodeposition as a simple and green route towards complex functional materials.