Seawater is one of the most abundant and clean hydrogen atom resources on our planet, so hydrogen production from seawater splitting has notable advantages. Direct electrolysis of seawater would not be in competition with growing demands for pure water. Using green electricity generated from renewable sources (e.g., solar, tidal, and wind energies), the direct electrolytic splitting of seawater into hydrogen and oxygen is a potentially attractive technology under the framework of carbon-neutral energy production. High selectivity and efficiency, as well as stable electrocatalysts, are prerequisites to facilitate the practical applications of seawater splitting. Even though the oxygen evolution reaction (OER) is thermodynamically favorable, the most desirable reaction process, the four-electron reaction, exhibits a high energy barrier. Furthermore, due to the presence of a high concentration of chloride ions (Cl−) in seawater, chlorine evolution reactions involving two electrons are more competitive. Therefore, intensive research efforts have been devoted to optimizing the design and construction of highly efficient and anticorrosive OER electrocatalysts. Based on this, in this review, we summarize the progress of recent research in advanced electrocatalysts for seawater splitting, with an emphasis on their remarkable OER selectivity and distinguished anti-chlorine corrosion performance, including the recent progress in seawater OER electrocatalysts with their corresponding optimized strategies. The future perspectives for the development of seawater-splitting electrocatalysts are also demonstrated.

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High Selectivity Electrocatalysts for Oxygen Evolution Reaction and Anti-Chlorine Corrosion Strategies in Seawater Splitting

Using copper-based biocathodes to improve carbon dioxide conversion efficiency into methane in microbial methanogenesis cells

The electroreduction of CO2 and CO into valuable chemicals and fuels powered by renewable electricity can tackle anthropogenic carbon emissions and close the carbon cycle. However, both CO2 and CO have low solubility in aqueous electrolytes, affording their sluggish mass transport across the electrolyte. CO2/CO electroreduction in a flow electrolyzer can tackle this problem by directly delivering the gaseous reactant to the electrode surface. Significant progress has been made recently in simultaneously obtaining high reaction rates and high product selectivity using flow cell configurations. This perspective highlights how different flow cell designs impact CO2/CO electroreduction and outlines potential strategies that may further improve the cell performance. The challenges and opportunities related to fundamental and engineering aspects are also discussed. 

Progress and Understanding of CO2/CO Electroreduction in Flow Electrolyzers

Recent progress in Green Ammonia: Production, applications, assessment; barriers, and its role in achieving the sustainable development goals

http://manuscript.elsevier.com/S0378775322003524/pdf/S0378775322003524.pdf

Power and energy capacity tradeoffs in an all-aqueous copper thermally regenerative ammonia battery

The EMS Energy Institute, The Pennsylvania State University, University Park, Pennsylvania, United States of America Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America

An All-Aqueous Thermally Regenerative Ammonia Battery Chemistry Using Cu(I, II) Redox Reactions

Saline water represents an inexhaustible source of water for hydrogen production from electrolysis. However, direct saltwater splitting faces challenges due to chlorine evolution at the anode and the development of Nernst overpotential due to sodium ion transport competition with protons across the membrane. A new approach to minimize chlorine evolution and improve performance is proposed here by using a humidified gas stream (no liquid electrolyte) for the anode and a liquid saltwater catholyte. Charge repulsion of chloride ions by the proton exchange membrane (PEM) resulted in low chlorine generation, with anodic faradaic efficiencies for oxygen evolution of 100 ± 1% with a synthetic brackish water (50 mM NaCl, 3 g L−1) and 96 ± 2% with synthetic seawater (0.5 M NaCl, 30 g L−1). The enhanced proton transport by the electric field enabled more efficient pH control across the cell, minimizing sodium ion transport in the absence of a liquid anolyte. The vapor-fed anode configuration showed similar performance to a conventional PEM electrolyzer up to 1 A cm−2 when both anode and cathode were fed with deionized water. Much lower overpotentials could be achieved using the vapor-fed anode compared to a liquid-anolyte due to the reduced sodium ion transport through the membranes, as shown by adding NaClO4 to the electrolytes. This vapor-fed anode configuration allows for direct use of saltwater in conventional electrolyzers without additional water purification at high faradaic efficiencies.

Using a vapor-fed anode and saline catholyte to manage ion transport in a proton exchange membrane electrolyzer

The Impact of Fiber Arrangement and Advective Transport in Porous Electrodes for Silver-Based Thermally Regenerated Batteries

/pdf/carbon-degradation-and-kinetics-in-a-vanadium-4-5-4pd328wex3.pdf

Nicholas R. Cross

Papers

An All-Aqueous Thermally Regenerative Ammonia Battery Chemistry Using Cu(I, II) Redox Reactions

Using a vapor-fed anode and saline catholyte to manage ion transport in a proton exchange membrane electrolyzer

The Impact of Fiber Arrangement and Advective Transport in Porous Electrodes for Silver-Based Thermally Regenerated Batteries

Carbon degradation and kinetics in a vanadium (4/5) electrolyte