Interface-engineered Bi2Te3-MXene heterostructure for multifunctional energy conversion and storage

Topological insulators (TIs), particularly bismuth telluride (Bi 2 Te 3 ), exhibit exceptional electronic properties but are frequently hindered by low intrinsic conductivity and structural instability in their bulk form. In this work, we report a strategic interface engineering approach to hybridize layered Bi 2 Te 3 nanosheets with conductive Ti 3 C 2 T x MXene, creating a high-performance bifunctional heterostructure. Phase-pure Bi 2 Te 3 was synthesized via a surfactant-assisted hydrothermal method and integrated into MXene matrix, which functions as both a conductive scaffold and a structural buffer. Synchrotron-based structural analysis and temperature-dependent Raman spectroscopy demonstrate that MXene incorporation modifies the structural and vibrational characteristics of Bi 2 Te 3 , while the TOF-SIMS analysis indicates the effective passivation of MXene for the chalcogenide surface against oxidation of Bi 2 Te 3 . The resulting Bi 2 Te 3 /Ti 3 C 2 T x composite exhibits superior electrocatalytic activities, delivering a low overpotential of 260 mV at 100 mA·cm − 2 for the hydrogen evolution reaction (HER), 490 mV at 100 mA·cm − 2 for the oxygen evolution reaction (OER), and an onset potential of 0.81 V for the oxygen reduction reaction (ORR), significantly outperforming pristine Bi 2 Te 3 . Mechanistic study probes indicate HER proceeds predominantly at Bi sites enabled by partial Bi-O surface termination while MXene supplies rapid electron conduction and defect sinks that stabilize catalytic centers. These results suggest that engineered 2D/2D heterojunctions provide a versatile platform for optimizing charge transport and ion kinetics in next-generation energy conversion and storage systems.