Elevating electrode catalyst stabilization for long-term intermittent alkaline seawater electrolysis

The production of hydrogen (H 2 ) via electrocatalytic water splitting is a promising approach for reducing reliance on fossil fuels and promoting sustainable development [1][2][3] .In this context, the development of anion exchange membrane water electrolyzers for practical overall water splitting has emerged as a key research focus in electrochemical energy conversion [4][5][6] .Given the scarcity of freshwater resources and the rapid expansion of renewable energy sources such as wind and solar power, seawater electrolysis driven by renewable electricity has attracted considerable attention (Figure 1a) [7][8][9][10] .In practical electrolysis, research has traditionally focused on the anode due to challenges such as corrosion and competing side reactions [11,12] .Simultaneously, the cathode is polarized to a reducing potential to drive the hydrogen evolution reaction (HER), and this applied potential inherently offers electrochemical protection, mitigating oxidative degradation and corrosion caused by reactive species in the seawater electrolyte [13,14] .A frequently overlooked factor, however, is that electricity from renewable sources is often intermittent, leading to repeated start-up and shutdown cycles in seawater electrolysis systems.During these off periods, the cathode is no longer maintained at a protective reducing potential, resulting in significant catalyst oxidation and posing a critical challenge to long-term stability under harsh operating conditions.Figure 1.(a) Schematic of an alkaline seawater electrolyzer illustrating the start and shutdown states powered by renewable energy; (b) Schematic illustrating the HER process during operation and the passivation/recovery mechanism during shutdown/start at a corrosive potential in intermittent electrolysis.HER: hydrogen evolution reaction.