The results revealed that, in the case of PC, U extraction products were precipitated exclusively on the TNA photocatalyst (Figure ), which confirmed that the blockage of the photocatalyst active sites by extracted U was responsible for the poor stability of the PC U extraction technology . On the contrary, extracted U was predominantly (78.4%) precipitated on the Ti cathode in the case of PEC (Figure ), even though a small fraction was found on the TNA photocatalyst, most probably as adsorbed species . Therefore, the spatial separation of the U precipitation sites and the photocatalyst could explain the stable photoactivity of the TNA photoanode and therefore the stable photoelectrons output in PEC method. More interestingly, the continuously U precipitation onto the Ti cathode in the PEC method did not decrease its U reduction capacity (Figure ). To clarify this aspect, in-situ electrochemical impedance spectroscopy (EIS) analysis was carried out to monitor the interfacial charge transfer resistance changes in real-time during the PEC U extraction. The curves shrank slightly during the experiment (Figure ), and the fit results revealed gradual decrease in interfacial charge transfer resistance of the Ti cathode (Supplementary Note 6), which could facilitate the U reduction. This finding was consistent with the slightly increasing pattern of the current during one cycle (Figure and Figure ), and the similar currents among different continuous cycles (Figure ). The results here suggested that the U precipitates on the Ti cathode could facilitate further U deposition, instead of blocking the active sites.