A Selective Copper Based Oxygen Reduction Catalyst for the Electrochemical Synthesis of H<sub>2</sub>O<sub>2</sub> at Neutral pH
Bas van Dijk, Rick Kinders, Thimo Ferber, Jan P. Hofmann, Dennis G. H. Hetterscheid
Abstract
Abstract H 2 O 2 is a bulk chemical used as “green” alternative in a variety of applications, but has an energy and waste intensive production method. The electrochemical O 2 reduction to H 2 O 2 is viable alternative with examples of the direct production of up to 20% H 2 O 2 solutions. In that respect, we found that the dinuclear complex Cu 2 (btmpa) (6,6’‐bis[[bis(2‐pyridylmethyl)amino]methyl]‐2,2’‐bipyridine) reduces O 2 to H 2 O 2 with a selectivity up to 90 % according to single linear sweep rotating ring disk electrode measurements. Microbalance experiments showed that complex reduction leads to surface adsorption thereby increasing the catalytic current. More importantly, we kept a high Faradaic efficiency for H 2 O 2 between 60 and 70 % over the course of 2 h of amperometry by introducing high potential intervals to strip deposited copper ( dep Cu). This is the first example of extensive studies into the long term electrochemical O 2 to H 2 O 2 reduction by a molecular complex which allowed to retain the high intrinsic selectivity of Cu 2 (btmpa) towards H 2 O 2 production leading to relevant levels of H 2 O 2 .