Tunable Infrared Sensing Properties of MXenes Enabled by Intercalants

Abstract

Abstract Light interaction physical properties of MXenes are fundamentally important and promising for developing new broadband photodetection applications. In this work, the significant influence of intercalants on the photo‐electronic properties of MXenes is studied. It is found that the intercalated H 2 O‐induced inter‐flake resistance greatly restricts the photon excitation responsivity of Ti 3 C 2 T x , resulting in a slow and irreversible resistance change under laser irradiation. After deintercalation of H 2 O by in situ laser writing, the resistance of Ti 3 C 2 T x responds fast and reversibly to laser excitation and the variation range is proportional to laser power. By extending the findings to another MXene member, Mo 2 TiC 2 , the intercalant induced resistance is successfully developed for optoelectronic detection. By selectively deintercalating H 2 O in the as‐prepared Mo 2 TiC 2 which is co‐intercalated by H 2 O and TMAOH, bare TMAOH intercalated Mo 2 TiC 2 shows fast and reversible resistance changes with laser. Moreover, the resistance of bare TMAOH intercalated Mo 2 TiC 2 shows a negative temperature coefficient behavior while the fully deintercalated Ti 3 C 2 T x shows a positive temperature behavior. These findings elucidate the understanding of the optoelectronic properties of MXenes and provide insights into the engineering of interfacial chemistry of MXenes for performance enhancement toward various detectors/sensors beyond optoelectronic applications.