Figure 3. Comparison of the electrochemical pumping with other technologies available for heavy-water production.

Data for the latter are adapted from ref. 2. The most common industrial methods are indicated by the black stars. Red circles: the demonstrated electrochemical pumping using CVD graphene (solid) and an estimate for monolayer hBN on Nafion (open). The red shaded area indicates the possible parameter space if process parameters such as temperature, membrane area, driving voltage and membranes' defectiveness are changed. The arrow shows the changes expected for graphene-on-Nafion and hBN-on-Nafion with increasing temperature to 60 °C. The grey area indicates the parameter space considered unsuitable for primary heavy water production. Abbreviations: ‘CECE'—combined electrolysis and chemical exchange, ‘dist.'—distillation. Note that the methods that are uneconomical for primary production of heavy water are used for final enrichment.