2D phosphides heterostructures on titanium microfiltration membrane for enhanced ampere-level current density overall seawater splitting

The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production, addressing the critical need for renewable energy sources and efficient resource utilization. However, direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction (ClER). To overcome these issues, we designed a novel NiP₂@CoP electrocatalyst on a porous titanium microfiltration (Ti MF) membrane. The obtained bifunctional NiP₂@CoP catalyst outperforms the Pt/C and IrO₂, as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm⁻² for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline seawater (1 M KOH + 0.5 M NaCl), respectively. Especially, only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm⁻² towards HER and OER in alkaline seawater, respectively. More importantly, no ClER was observed, demonstrating its excellent selectivity to OER. The selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas bubbles. Our promising outcomes obtained with NiP₂@CoP catalysts on Ti MF support, therefore, pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.