About this Research Topic
Water electrolysis technologies are considered extremely promising for sustainable hydrogen production and energy storage, as they can be driven by renewable or waste electricity/heat sources. Furthermore, the oxygen by-product has no negative environmental effects and can be used in other applications to enhance the economic profitability of the electrolysis input energy conversion/storage process. The three main types of current water/steam electrolyzer technologies have distinct advantages and disadvantages. AWEs (alkaline water electrolyzers) are the only technology globally commercially-available at MW scale. PEMWEs (proton exchange membrane water electrolyzers) have advantages for operation with variable power supply and at lower part loads than AWEs. SOSEs (solid oxide steam electrolyzers) have higher efficiencies than either AWEs or PEMWEs, but face durability challenges at high-temperature operation. However, substantial research efforts are still required for electrolysis to reach technology maturity for large-scale energy storage.
The limitations in the overall energy efficiency of water electrolysis are essentially due to the overpotential of the oxygen and hydrogen evolution reactions (OER/HER) at the electrolyzer anode and cathode, respectively. To reduce these overpotentials, and in turn improve electrolyzer efficiency and durability, a range of electrocatalysts have been developed to increase the HER/OER kinetics (for example, non-precious metal carbon-based electrocatalysts).
The design of advanced electrolyzers requires a fundamental understanding of the electrolysis reaction mechanisms, based on theoretical knowledge of the electron transfer at electrode-electrolyte interfaces, time-resolved surface science analytics, atomistic description of the semiconductor-water interface, electrochemical stability of metastable materials, standardization of the quantitative key metrics and performance indicators for heterogeneous electrocatalysts, as well as density functional theory (DFT), superconducting quantum interference device (SQUID) and X-ray absorption near edge structure (XANES) calculations on atomic levels, and experimental validations of the involved catalytic mechanisms.
This Research Topic collection is intended to disseminate research progress in the development of renewable energy-driven water electrolysis, and to encourage further research and investments in this technology. The Topic Editors welcome Original Research, Review and Perspective article contributions addressing the following aspects:
- Improvement of electrocatalytic performance via the following techniques:
- Synthesis of hybridizing materials, such as through alloying, synthesis of multimetallic compounds, use of template techniques, or development of bifunctional catalysts.
- Improvements in stability of high-temperature ceramic catalysts, such as through the use of Janus catalysts and pre-catalysts.
- 3-D materials possessing long-range porous structures that can facilitate charge transfer and mass transport, etc., is anticipated.
- Development of robust and stable membrane separators with high ionic conductivity and low H2/O2 gas- and ionic-crossover, to improve electrolyzer cost-effectiveness.
- Novel electrodes processing and/or new designs to suppress gas bubble formation.
- Development of waste water electrolyzers to address water availability issues.
- Economic assessment in relation to long-term durability, scalability and cost of the water electrolysis system, also comprising attractiveness and supply/market flexibility.
- Use of electrolyzers with bipolar- and multi-membranes, and/or different design configurations, to overcome challenges concerning the production, storage and transport of H2, and to develop tandem photoelectrochemical cells for solar water splitting, namely for solar driven decoupled water splitting, which are still at the laboratory scale.
- Using novel sensing techniques of the catalyst-solution interface for developing improved electrocatalyst materials.
Keywords: electrocatalysts for HER/OER, water electrolysis technologies, stability of electrodes for water splitting, renewable energy-driven water electrolysis, design of advanced water electrolyzers
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.