From real seawater to sustainable energy via supported green electrocatalysts: Progress, hurdles, and future directions

The direct splitting of real seawater, a largely available natural feedstock, for green hydrogen generation represents a strategically appealing strategy toward energy and environmental sustainability, supporting the goal of carbon neutrality. However, scaling up seawater electrolysis faces some crucial challenges such as the sluggish reaction kinetics, the occurrence of impurities, and the competitive anodic chlorine oxidation, all of which reduce process efficiency. Consequently, the development of green, economically viable, stable and active electrocatalysts selective toward oxygen evolution, and suppressing the corrosive chlorine chemistry, is highly required. In this context, the present review aims at summarizing recent advances in surface and interface engineering for noble-metal-free inorganic electrocatalysts applied to seawater splitting. This work is focused exclusively on inorganic materials tested in real, not simulated, seawater electrolysis, which is by far more challenging. The primary design strategies to improve their functional performances are critically overviewed, with the aim of guiding rational catalysts fabrication and tackling the actual open problems of this technology. Besides the current state of research in this field, an outlook on the future development for clean hydrogen generation is also provided.