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It is crucial to distinguish the performance of different phases of molybdenum disulfide (MoS 2) for Hg(II) removal owing to its distinct activity and atomic arrangement. Herein, we directionally synthesized three nanocrystalline MoS 2 with metallic 1T, semiconducting 2H, and 1T/2H mixed M phase, and elucidated Hg(II) adsorption behaviors. Kinetics experiments suggested that the 1T-MoS 2 exhibited the most promising performance toward Hg(II) removal over other two counterparts (2H- and M-MoS 2), including highest mass transfer coefficient of 1.85 × 10−6 m s−1, an extraordinary selectivity of 3.89 × 108 mL g−1 and deep removal capability with residual concentration lower than 0.35 μg L−1. Combining various characterization tools, the phase-mediated removal mechanism was unveiled for Hg(II) onto 1T-MoS 2. Specifically, Hg(II) species could be selectively captured by 1T-MoS 2 via Hg-S interactions, enabling a redox reaction involving electron transfer along conductive lamellas, where Hg(II) was reduced to Hg 2 Cl 2 crystals. Moreover, the 1T-MoS 2 also demonstrated a high adsorption capacity (1622 mg g−1), a broad pH working range (1–12) and superb selectivity for Hg(II) removal. Highly practical applicability of 1T-MoS 2 was confirmed for deep removal performance in various real water matrices. Great economic efficiency of the methodology was synergistically demonstrated by high adsorbent reusability (removal efficiency >99.9% over 3 cycles) and resources recovery feasibility (e.g., recyclable Hg 2 Cl 2 products). Overall, this work has demonstrated high applicability of 1T-MoS 2 for mercury removal and provides guidance for designing advanced nanoadsorbents from the perspective of crystal phase regulation. [Display omitted] • Three nanocrystalline MoS 2 with representative phases (1T, 2H, and mixed phase (M)) were directionally synthesized. • 1T-MoS 2 exhibited promising performance toward Hg(II) removal under various aqueous conditions. • Hg(II) could be captured by 1T-MoS 2 via Hg-S interactions, then reduced to Hg 2 Cl 2 crystals. • A high economic benefit system capable of simultaneous separation of adsorbents and recovery of Hg 2 Cl 2 products was developed. [ABSTRACT FROM AUTHOR]