High-performing catalysts for energy-efficient commercial alkaline water electrolysis
Sustainable Energy and Fuels
‘Green’ hydrogen produced from water electrolysis powered by renewable energy will play a critical role in the future global energy transition to ‘net zero’ carbon emissions. To this end, intensive efforts are needed to improve the energy efficiency with which green hydrogen can be made and thereby reduce its cost. A key required effort in this respect involves developing the most efficient and durable possible catalysts to facilitate the ‘hydrogen evolution reaction’ (HER) at the cathode and the ‘oxygen evolution reaction’ (OER) at the anode in alkaline water electrolysers. Most work in this regard has focused on improving the activity of catalysts at or around a standard current density of 10 mA cm−2 for both the HER and OER. However, to be practically useful, electrocatalysts must operate efficiently at commercial current densities, which are typically much higher; for example, commercial alkaline water electrolysers routinely operate at current densities of 200-700 mA cm−2. Reviews of such electrocatalysts and their suitability for commercial-scale water electrolysis are rarely reported. This work presents an overview of recent progress in this respect. The most energy efficient and durable electrocatalysts for the HER, the OER, and for overall water splitting, are identified, discussed, and prioritized with a view towards enhancing commercial alkaline water electrolysis. The major challenges involved in their preparation and operation, as well as potential avenues for further performance improvements as reliable, robust electrocatalysts for commercial alkaline electrolysis are also highlighted. The latest work on new technology development in alkaline water splitting is also presented. The high-performing catalysts that are most likely to accelerate the prospects of green hydrogen are listed in a comparative table. A discussion of future directions in this emerging field is also provided.
Open Access Status
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Australian National Fabrication Facility