Atomic-Scale Defected HfS₂ Nanosheets: A Novel Platform Enhancing Photocatalysis

Abstract

Recently, novel 2D materials with fascinating characteristics are extensively applied to design/fabricate high-activity and cost-effective photocatalysts for solar-driven fuels/chemicals generation. Among these 2D materials, HfS2 nanosheets (NSs) exhibit excellent features of large surface area, short bulk-to-surface distance, alterable band structures, and vast catalytic sites. Despite these features, no realistic experimental works on HfS2-based materials are reported in photocatalysis field. Moreover, it is interesting but challenging to realize atomic-scale engineering of compositions/structures for novel 2D materials and to relate these atomic-scale characteristics with the element/space/time-resolved charge kinetics of 2D materials-based photocatalysts. Herein, for the first time, atomic-scale defected HfS2 NSs are designed/synthesized. The as-synthesized HfS2 NSs are combined with various photocatalysts to acquire novel HfS2-TiO2, HfS2-CdS, HfS2-ZnIn2S4, and HfS2-C3N4 composites, respectively. Among them, HfS2-CdS exhibits the highest rate (5971 μmol g−1 h−1) on hydrogen (H2) evolution in triethanolamine aqueous solution, together with obviously-enhanced rates on H2 (2419 μmol g−1 h−1) and benzaldehyde (5.11 mmol g−1 h−1) evolution in benzyl alcohol aqueous solution. Various state-of-art characterizations reveal the element/space/time-resolved electron/hole kinetics in HfS2-CdS composites, disclosing that these atomic-scale S vacancies temporarily trapping electrons to facilitate spatiotemporal electron–hole separation/transfer. This work paves avenues to atomic-scale design/synthesis of new 2D-materials-based photocatalysts for sunlight utilization.