Rationally designed Ti3C2/N, S-TiO2/g-C3N4 ternary heterostructure with spatial charge separation for enhanced photocatalytic hydrogen evolution

Abstract

The charge separation and transfer are the major issues dominating the under-laying energy conversion mechanism for photocatalytic system. Construction of semiconductor-based heterojunction system considered to be viable option for boosting the spatial charge separation and transfer in the photocatalytic water splitting system. Here, we design a ternary heterojunction of Ti3C2/N, S-TiO2/g-C3N4 by thermal annealing and ultrasonic assisted impregnation method having a well-designed n-n heterojunction and noble metal free Schottky junction for adequate hydrogen evolution. The optimal content of 4 wt% Ti3C2 on N, S-TiO2/g-C3N4 (4-TC/NST/CN) exhibit the highest rate of hydrogen generation 495.06μ mol h−1 which is 3.1, 4.1 and 1.6 fold higher than the pristine N, S doped-TiO2, g-C3N4 and binary hybrid (N, S doped-TiO2/g-C3N4) respectively, with 7% apparent conversion efficiency (ACE). The increment in the activity is described to the robust photogenerated carrier separation and double charge transfer channels because of the formation of dual heterojunction (n-n heterojunction and Schottky junction). XRD and Raman results revealed the occupancy of Ti3C2 in the heterojunction due to the strong interaction between Ti3C2, with N, S doped-TiO2 and g-C3N4. The HRTEM analysis confirmed the formation of close interfacial junction between the Ti3C2, N, S doped-TiO2 and g-C3N4. Moreover, the higher photocurrent, low PL intensity and lower impedance arc suggested the lower charge carrier recombination rate in 4-TC/NST/CN heterojunction. This work represents a significant development to establish a sound foundation for future design of MXene-based ternary hybrid system towards significant charge carrier separation and transfer for H2 production activity.