The selective deposition of MoS2 nanosheets onto (101) facets of TiO2 nanosheets with exposed (001) facets and their enhanced photocatalytic H2 production

Abstract

One of the challenging issues in photocatalytic hydrogen (H2) production is to efficiently separate the photogenerated electron-hole pairs and require the enrichment of photogenerated electrons on the photocatalyst’s surface. Herein, a novel 2D-2D nanojunction of MoS2 nanosheets (NSs) selectively deposited on the (101) facets of TiO2 NSs with mainly exposed high-active (001) facets is prepared via a hydrothermal/annealing treatment combined with an photoreduction method using carbon fiber (CF) as templates. The obtained MoS2@TiO2 composite (selective deposition) photocatalyst exhibits a greatly enhanced photocatalytic H2 production activity at the optimal weight percentage of MoS2 (15 wt%), exceeding that of pure TiO2 NSs and MoS2@TiO2 composites (random deposition) by 32 and 3 times, respectively. The superior photoactivity of MoS2@TiO2 composites (selective deposition) is attributed to the synergistic promoting effects of the following factors: (i) the mainly exposed (001) facets of TiO2 NSs with higher surface energy in MoS2@TiO2 composites (selective deposition) facilitate the activation of water molecules and the photocatalytic reduction; (ii) the coexposed (101) and (001) facets can form a surface heterojunction within single TiO2 NS, which is beneficial for the transfer and separation of charge carriers; (iii) the MoS2 NSs are selectively deposited on the electrons-rich (101) facets of TiO2 NSs, which can effectively reduce the charge carriers recombination rate by capturing photoelectrons. This study presents an inexpensive photocatalyst for energy conversion to achieve highly efficient H2 evolution without noble metals.