Subnanometer nanowires (SNWs) refer to nanowires with diameters close to the size of a single crystal cell. SNWs show not only qualitative change in nature compared to the bulk materials or nanomaterials with larger size but also show several advantages in assembly and processing due to their polymer‐analog properties. However, the synthesis of SNWs is still a great challenge. Herein, a synthesis method of SNWs assisted by polyoxometalates is developed. Based on this method, several kinds of SNWs are prepared successfully, and the properties of the SNWs can be regulated efficiently and effectively, demonstrating the extensibility of this synthesis method. Among these SNWs, Bi2O3–PMoO SNWs show good photothermal conversion performance and can be processed into freestanding and flexible films through the wet‐spinning method. The Bi2O3–PMoO SNW films show good performance in solar steam generation and seawater desalination. The average stable evaporation rate can reach 1.38 kg m−2 h−1, and the efficiency is ≈91.1% under 1 sun illumination. The concentration of ions in the desalted seawater with the Bi2O3–PMoO SNWs film are reduced by four orders of magnitude, meeting the quality standards of drinking water and potential for practical utilization of solar energy in the seawater desalination.

The cluster–nuclei coassembled strategy provides an impressive way to obtain 1D subnanometer heteronanostructures, including subnanometer nanowires and subnanometer nanobelts. These nanomaterials have diameters and thicknesses close to the size of a unit cell and exhibit excellent performance originating from multicomponent synergy. This Mini Review summarizes the recent progress of these novel functional nanomaterials, including their properties and applications in catalysis, energy conversion, and other fields. On the basis of previous studies, the development direction of cluster–nuclei coassembled 1D subnanometer materials is pointed out.

1D superlattices with long‐ranged periodicity present extraordinary application properties due to their unique electronic structures. Here, the visible light driven synthesis of 1D single‐cluster chains constructed by polyoxometalate (POM) and Ag clusters is reported, where two types of clusters align alternatively along the nanowire. Low symmetrical POM clusters of [P2W17O61]10–, [P2W15O56]12–, and [EuW10O36]9– can be used as building blocks. The directly bonding cluster units result in interactive electronic structures of Ag and POM clusters, as well as the greatly promoted electron transfer during the redox reaction. The Ag–P2W17 nanowires perform significantly enhanced activities in both electrochemical sensing and catalytic gasoline desulfurization compared with individual building blocks, demonstrating the extraordinary application properties and promising potentials of cluster‐based heteroconstructions.