The controllable preparation of polyoxometalate-based sub-1 nm materials and their applications in energy storage and conversion

Sub-1 nm materials (SNMs) refer to materials with a size of 1 nm or less. Their size is small enough, with a sufficiently large specific surface area and nearly 100% atomic exposure, enabling them to expose more active sites. Therefore, SNMs usually possess excellent properties in optics, electricity, and catalysis, etc. Among SNMs, polyoxometalate (POM)-based SNMs have shown significant advantages and potential in energy storage and conversion due to the special sub-1 nm structure and the synergetic effect of multiple components. Although plenty of POM-based SNMs have been reported, there are few systematic reviews on the synthetic methods of POM-based SNMs and their applications in energy storage and conversion. This review will summarize the latest progress in the synthesis of POM-based SNMs and their achievements in energy storage (including lithium-ion battery, sodium-ion battery, Li-O₂ battery, Zn-O₂ battery, Li-S battery, etc.) and energy conversion (photothermal conversion, solar steam generation and seawater desalination). Then, current critical challenges and future perspectives are discussed. We believe that this review will provide new insights into the rational design and development of efficient POM-based SNMs suitable for energy storage and conversion.