Selective Electrochemical Oxidation of H2O to H2O2Using Boron-Doped Diamond: An Experimental and Techno-Economic Evaluation

Abstract

Selective water oxidation to hydrogen peroxide has emerged as an economically attractive replacement for oxygen in electrochemical hydrogen production by water splitting. Here, boron-doped diamond (BDD) is shown to be a promising anode material for anodic H2O2 formation. Faradaic efficiencies of up to 31.7% at 2.90 V versus the reference hydrogen electrode and a current density of 39.8 mA cm-2 were observed, corresponding to a H2O2 production rate of 3.93 μmol min-1 cm-2. A techno-economic evaluation based on the experimentally obtained values demonstrates that the corresponding levelized cost of hydrogen (LCH) is significant ($62.0 kg-1). Particularly, the current market price of BDD limits its implementation as a selective water oxidation anode for H2O2 generation. The sensitivity analysis however suggests that the LCH can be significantly improved by either decreasing the anode cost or increasing the current density. Both approaches are in fact feasible to allow for cost-effective electrochemical H2 production and even competition with H2 obtained from steam methane reforming. This study will guide ongoing research efforts toward BDD development and implementation of selective water oxidation to hydrogen peroxide.