“…42 However, the concentration of • OH detected by the BA method is much lower than the actual yield because most of the hydroxyl groups are consumed by water or self-deactivation in a short period of time. 43 As shown in Figure S7a, more than 40 μM of • OH were produced in the system within 120 min, indirectly proving that • OH effectively reacted with BA. Subsequently, to find the factors affecting the recovery of Ni to Ni−EDTA, we performed • OH quenching experiments with different concentrations of quenching agents to explore whether • OH affects the recovery of Ni.…”