Fig. 3
a The chronoamperometric curve at each stage; integrating the area under the curve gives the total charge passing through the membrane in Coulombs for each stage. b The average photocurrent vs. the Li concentration in the feed solution at different stages. c The number of different ions passing through the membrane (bar chart) and the contributed faradaic efficiencies for each stage (red star). d The XRD pattern of the Li3PO4 sediment collected from enrichment solution after three extraction stages. The inset shows the enriched Li solution and the Li3PO4 sediment