Utilization of Strong Charge Transfer Efficiency at 2H-1T Phase Boundary of MoS2 for Superb High-Performance Charge Storage

TL;DR

This study demonstrates that the phase boundary between 2H and 1T MoS2 enhances charge transfer, leading to high-capacity energy storage devices with superior performance, by combining theoretical and experimental approaches.

Contribution

It reveals the strong charge transfer at 2H/1T MoS2 boundaries and utilizes this for high-performance supercapacitors, a novel approach in phase boundary engineering.

Findings

Achieved gravimetric capacitance of 272 F g-1

Attained volumetric capacitance of 685 F cm-3

Fabricated flexible supercapacitor with 46.3 mWh cm-3 energy density

Abstract

Transition metal dichalcogenides like MoS2 can exist many phases like the semiconducting 2H and the metallic 1T phases which have shown intriguing properties for energy and electrocatalytic applications. However, the 2H and 1T phases normally distribute coherently in a single-layered MoS2 sheet which is accompanied with ubiquitous hetero-phase boundaries. In this work, by using density functional theory and electrochemical measurement, we report strong charge transfer ability between 2H/1T phase boundary of MoS2 and graphene which accounts for a superb coexistence of gravimetric and volumetric capacitances of 272 F g-1 and 685 F cm-3. As a proof-of-concept application, a flexible solid-state asymmetric supercapacitor based on MoS2/graphene is fabricated, showing a remarkable energy and power densities (46.3 mWh cm-3 and 3.013 Wcm-3). Our work shows the promise of promoting the efficiency of charge flow and energy storage through engineering phase boundary and interface in phase-change materials.