Emerging Application of High-Entropy MXene in Efficient Photoelectrochemical-Type Photodetectors and Wideband Mode Lockers

High-entropy (HE) MXenes represent a novel class of 2D materials within the MXene family, which are drawing widespread attention because of their diverse compositions and robust physicochemical properties. However, the exploration of HE-MXenes in optoelectronic domains is relatively limited. This study unveils the rapid photoresponse and superior nonlinear optical (NLO) characteristics of HE-MXene TiVCrMoC3Tx nanosheets (NSs) through comparison with ordinary MXene Ti3C2Tx NSs. Transient absorption spectroscopy reveals that the few-layer TiVCrMoC3Tx NSs excel in photoelectrochemical-type photodetectors with swift response properties. Additionally, the advantage of HE structures is further validated by NLO measurement system, which show that few-layer TiVCrMoC3Tx NSs exhibit stronger saturable absorption than Ti3C2Tx NSs. First-principles calculations based on the special quasi-random structure method reveal that the transition behavior of HE-MXene is similar to that of a semiconductor with direct bandgap, and this is ascribed to the main reason of strong photoelectric response. Taking advantage of the NLO properties of the TiVCrMoC3Tx NSs, all-optical devices based on these NSs are applied to mode-locked fiber lasers at 1, 1.5, and 2 mu m wavebands, respectively. This investigation provides meaningful guidance for the future design and application of HE-MXenes in high-performance optoelectronic devices. This study reveals the excellent nonlinear optical properties of high-entropy MXene TiVCrMoC3Tx nanosheets in nonlinear optical measurement systems and the fast optical response as photoelectrochemical-based photodetectors by comparing with the ordinary MXene Ti3C2Tx nanosheets and demonstrates it by first-principles calculations. In addition, all-optical devices based on TiVCrMoC3Tx nanosheets are designed and applied to mode-locked fiber lasers at 1, 1.5, and 2 mu m bands, respectively. image