In this Letter, we reported the standard reduction potential of Ag2+/Ag+—a known value—as +1.98 V versus the saturated calomel electrode. However, the value of +1.98 V corresponds to the reduction potential versus the standard hydrogen electrode1. The correct value versus the saturated calomel electrode is +1.74 V, as stated in ref. 20 of the Letter. This error does not change the results or conclusions of the work. The original Letter has been corrected online.