Extended Data Fig. 6: NIR emission to measure ¹O₂ yields.

a, ¹O₂ NIR emission spectrum as reported in the literature¹² and transmission of the used bandpass filter. b, Representative output signal upon injecting RM^ox solution onto KO₂ powder. The integral of the recorded signal was used to determine the ¹O₂ yields. The example shown is with MPT. c, Representative output signal of the NIR detector upon injecting Li⁺ electrolyte solution onto KO₂ powder. The setup was similar to the one shown in Extended Data Fig. 4, except that a cuvette replaced the glass vial and the NIR detector was placed next to it. The example shown is with a Li⁺ mole fraction of 0.166. d, Representative NIR signal upon injecting H⁺ solution containing buffer onto KO₂ powder. The example shown is with BR buffer at pH 2.2. e, Output signal of the NIR detector upon injecting H₂SO₄ (pH 1.58) solution without any buffer onto KO₂ powder.