Punctured Two-Dimensional Sheets for Harvesting Blue Energy

The challenges of global climate change and the world's growing demand for energy have brought the need for new renewable energy sources to the top of the international community's agenda. We have known for many centuries that energy is released upon mixing seawater and freshwater, yet it was just a few decades ago that it became clear how this energy can be converted into electricity instead of heat. As a result, the blue energy rush has raised and set new strategies in different science and technology sectors, leading to the construction of a new generation of plants and other technological investments. Among many approaches, pressure-retarded osmosis has emerged as a promising method to collect the largest amount of produced blue energy. In this Perspective, we highlight the advances in the development of ultrathin membranes based on two-dimensional materials. We discuss the most relevant synthetic methods devised to generate atomically thin membranes for pressure-retarded osmosis and retarded electrodialysis applications, and we provide some critical views on the greatest challenges in this thrilling research area.