Electrochemically Generated Platform Oxidizers: An Enabler for the Hydrogen Economy

Conspectus A highly attractive alternative anode reaction for electrochemical hydrogen production is the formation of platform oxidizers instead of molecular oxygen. These platform oxidants are high-value products and can therefore help cofinance hydrogen production. For most electro-organic reactions, the electrochemical conditions for hydrogen production would be incompatible, due to the high current density required, whereas the anodic production of platform oxidizers demonstrates technical complementarity. The broad range of applications for such platform oxidants and versatility allow for broad applications and large-scale use, including the synthesis of complex, high-value target products. For platform oxidizing agents that utilize elements that are in limited supply or pose environmental concerns, a closed-loop system must be established between their production and recycling. The recovery and regeneration of reaction waste into platform oxidizing agents must ensure that no cross-contamination occurs during the production of the target products and that these platform oxidizing agents can be transported and stored safely. Among many other platform oxidants, periodates and peroxodicarbonates are the most promising. This is because either a wide range of applications is already known, or the resulting byproducts serve as critical reactants for processes involving biogenic feedstock. Periodates have also been demonstrated to work in a closed-loop system: if these platform oxidants are used on-site, much simpler and easier-to-store starting compounds can be used, which then yield harmless coproducts that do not need to be recovered, e.g., alkali carbonates. In most cases, these platform oxidizers can be produced in an undivided electrolytic cell. This improves the energetics of the electrolytic reaction. The anodic reaction typically occurs at electrodes with a high overpotential for the oxygen-evolution reaction. Due to the temporary storage of the platform oxidants, this approach can contribute efficiently to the transformation of the chemical industry, as it allows safe hydrogen generation on demand and is tailored to the electricity supply.