Supramolecular tuning of supported metal phthalocyanine catalysts for hydrogen peroxide electrosynthesis

Abstract

Two-electron oxygen reduction offers a route to H2O2 that is potentially cost-effective and less energy-intensive than the industrial anthraquinone process. However, the catalytic performance of the highest performing prior heterogeneous electrocatalysts to H2O2 has lain well below the >300 mA cm−2 needed for capital efficiency. Herein, guided by computation, we present a supramolecular approach that utilizes oxygen functional groups in a carbon nanotube substrate that—when coupled with a cobalt phthalocyanine catalyst—improve cobalt phthalocyanine adsorption, preventing agglomeration; and that further generate an electron-deficient Co centre whose interaction with the key H2O2 intermediate is tuned towards optimality. The catalysts exhibit an overpotential of 280 mV at 300 mA cm−2 with turnover frequencies over 50 s−1 in a neutral medium, an order of magnitude higher activity compared with the highest performing prior H2O2 electrocatalysts. This performance is sustained for over 100 h of operation.