Phase-Engineered 1<i>T</i>/2H-MoS₂ Heterostructures for High-Conversion-Efficiency Lithium-Ion Photobatteries.

Abstract

Photobatteries promise a revolutionary approach to both harvesting and storing solar energy; however, their development has been limited by rapid carrier recombination and the absence of interfaces to direct charge flow effectively. Here, we construct an in-plane 1<i>T</i>/2H-MoS₂ heterostructure chemically connected onto carbon nanotubes (CNTs) that integrate metallic 1T-MoS₂, semiconducting 2H-MoS₂, and conductive CNTs into a multi-interface framework. This architecture generates a built-in electric field across the 1<i>T</i>/2H-MoS₂ junction and provides continuous directional pathways for rapid electron extraction and transfer. Ultrafast transient absorption spectroscopy identifies long-lived charge-separated states with a prolonged carrier lifetime (τ₂ ≈ 731 ps) in the 1<i>T</i>/2H-MoS₂ heterostructure, more than double that of 2H-MoS₂@CNTs. Meanwhile, Kelvin probe force microscopy reveals a pronounced light-induced potential gradient (∼75 mV), providing direct nanoscale evidence of efficient carrier extraction. These synergistic effects promote efficient charge separation and transport, enabling superior photoassisted lithium-ion storage. The 1<i>T</i>/2H-MoS₂@CNTs-based lithium-ion photobattery demonstrates an increased storage capacity from 493.7 to 624.9 mAh g^-1 at 0.5 A g^-1 under illumination and a maximum photoconversion and storage efficiency of 6.62%, achieving an external voltage-free self-charging process. This study underscores rational multi-interface engineering to effectively integrate light harvesting and electrochemical storage for self-charging energy systems.