Molten Salt Engineering: Resolving the Contradiction and Core Challenges Between High Temperature and Precise Regulation to Achieve Green Synthesis of Advanced Nanomaterials

ABSTRACT The field of materials synthesis has long faced the challenge of reconciling high‐temperature reactions with atomic‐level precise regulation, further highlighting the limitations of traditional synthesis technologies. This contradiction is particularly prominent in the preparation of advanced nanomaterials. By virtue of the unique properties of its reaction medium, molten salt synthesis (MSS) technology resolves the core contradiction between high temperature and precise regulation, providing a novel pathway for the green and controllable synthesis of nanomaterials and driving a paradigm shift in the field of materials synthesis. Traditional hydrothermal methods are limited by the thermal stability of solvents and cannot adapt to high‐temperature reaction scenarios. In contrast, solid‐state reactions suffer from issues such as high diffusion barriers and uneven reactivity. These problems not only hinder the preparation of high‐performance nanomaterials but also pose numerous challenges, including high energy consumption at elevated temperatures, reliance on toxic reagents like hydrofluoric acid (HF), and difficulties in waste liquid treatment, which are contrary to the concept of green synthesis. The special ionic environment constructed by molten salts combines high‐temperature stability, excellent ionic transport capacity, and flexibly tunable chemical conditions. Through four core functions dynamic reaction medium, surface termination regulation, structural stabilization, and atmospheric protection—it enables the efficient, green, and controllable synthesis of nanomaterials. This study further discusses the challenges and prospects of this technology from three dimensions: reaction mechanisms, large‐scale applications, and sustainability optimization. The core focus is on advancing sustainability optimization, specifically including the development of heavy metal‐free and biodegradable green molten salt systems, the improvement of efficient purification and recycling processes for salt media in large‐scale production, and the establishment of green evaluation criteria covering the entire lifecycle of nanomaterials. These efforts aim to position MSS technology as a benchmark for the precise synthesis and low‐carbon manufacturing of advanced nanomaterials.