Electrochemically Activatable Liquid Organic Hydrogen Carriers and Their Applications

Abstract

Hydrogen has been chosen as an environmentally benign energy source to replace fossil-fuel-based energy systems. Since hydrogen is difficult to store and transport in its gaseous phase, thermochemical liquid organic hydrogen carriers (LOHCs) have been developed as one of the alternative technologies. However, the high temperature and pressure requirements of thermochemical LOHC systems result in huge energy waste and impracticality. This Perspective proposes electrochemical (EC)-LOHCs capable of more efficient, safer, and lower temperature and pressure hydrogen storage/utilization. To enable this technology, several EC-LOHC candidates such as isopropanol, phenolic compounds, and organic acids are described, and the latest research trends and design concepts of related homo/hetero-based electrocatalysts are discussed. In addition, we propose efficient fuel-cell-based systems that implement electrochemical (de)hydrogenation of EC-LOHCs and present prospects for relevant technologies.

Recent progress and perspectives of liquid organic hydrogen carrier electrochemistry for energy applications

“…The LOHC electrochemical redox reactions under acidic and basic conditions can be depicted with eqn (1) and (2), respectively. 15,16 …”

“…However, DHA is not stable and gets rapidly oxidized to irreversible products particularly when the pH exceeds 8, limiting its practical viability. 16 These instances highlight the crucial necessity for a comprehensive understanding of these underappreciated LOHC candidates to unlock their full potential and address the challenges hindering their adoption.…”

Review and Perspective of Nickel and Its Derived Catalysts for Different Electrochemical Synthesis Reactions in Alkaline Media for Hydrogen Production

“…In recent years, the electrochemical oxidation of aldehydes to generate greater value products is an essential reaction for catalysis and energy sciences. The electrochemical aldehyde oxidation is not only useful for organic synthesis, but also serves as a viable anode reaction when combined with H 2 evolution or other reductive fuel production reactions for improving efficiency and utility by replacing water oxidation as the oxidative reaction. , Aldehydes are subjected to oxidation in this process, which results in the loss of electrons and the formation of carboxylic acids or other functional groups. An electrocatalyst is frequently present during the reaction to aid in the transport of electrons.…”

Mixed Potential Driven Self-Cleaning Strategy in Direct Isopropanol Fuel Cells

“…Recently, liquid organic hydrogen carrier (LOHC) has been emerging as an alternative to hydrogen storage and transportation . Among LOHCs, electrochemistry-based systems, including isopropanol (IPA) and phenolic acid, present advantages as they operate at moderate temperature (<80–100 °C) and pressure (<1–5 bar) compared to the thermochemical systems that typically require higher temperature and pressure (>300 °C, about 30–50 bar) . Electrochemistry-based systems can also use in direct LOHC fuel cell which generates electricity using LOHC directly as a fuel without the process for extracting hydrogen .…”