Increasing fresh water demand for drinking and agriculture is one of the grand challenges of our age. Graphene oxide (GO) membranes have shown a great potential for desalination and water purification. However, it is challenging to further improve the water permeability without sacrificing the separation efficiency, and the GO membranes are easily delaminated in aqueous solutions within few hours. Here, we report a class of reduced GO membranes with enlarged interlayer distance fabricated by using theanine amino acid and tannic acid as reducing agent and cross-linker. Such membranes show water permeance over 10,000 L m⁻² h⁻¹ bar⁻¹, which is 10–1000 times higher than those of previously reported GO-based membranes and commercial membranes, and good separation efficiency, e.g., rhodamine B and methylene blue rejection of ~100%. Moreover, they show no damage or delamination in water, acid, and basic solutions even after months.

Vacancies enhance proton conductivity: Proton-exchange membranes (PEMs) allow for the transport of protons while acting as electrical insulators and ensuring that reactants are kept apart; therefore, they are a key component in devices such as low-temperature fuel cells. PEMs are typically made from polymers or materials embedded in a polymer matrix and need to operate in conditions of very high humidity. Starting with an inorganic, layered material, CdPS ₃ , Qian et al. show that the removal of a small amount of cadmium introduces vacancies that greatly increase the proton conductivity of the PEMs (see the Perspective by Wang and He). The process works for manganese-based membranes as well, and high lithium ion transport was also observed. Science , this issue p. 596 ; see also p. 525