Hierarchical Cu2S nanorods with different crystal phases for asymmetrical supercapacitors and visible-light photocatalysis

Abstract

Nanomaterials with hierarchical structures have attracted much attention recently due to their impressive behavior in many fields. Herein, hierarchical Cu₂S nanorods with monoclinic and hexagonal phases are first in situ grown on copper sheets by simple hydrothermal methods. The solvent largely influences the feature of Cu₂S nanorods during the growth process and the proposed mechanism is elaborately elucidated for these different Cu₂S nanorods. Owing to their wheat-like architecture and higher electrical conductivity, the hexagonal Cu₂S nanorods exhibit superior electrochemical performance with a specific capacitance of 346 mF cm⁻² at 5 mA cm⁻² and more than 90% capacitance after 2000 cycles. The solid-state asymmetrical supercapacitors based on the hexagonal Cu₂S electrodes have a specific capacitance of 172 mF cm⁻² at 5 mA cm⁻² and excellent electrochemical stability with ∼90% capacitance after 2000 cycling tests. Moreover, the hierarchical Cu₂S nanorods show great photocatalytic ability in the degradation of methylene blue (MB) and rhodamine B (RhB) dyes with the assistance of H₂O₂ under visible light. This work provides a way to fabricate copper sulfides with hierarchical structures and multi-functions.