Phosphorus–tungsten dual-doping boosts acidic overall seawater splitting performance over RuOx nanocrystals

Abstract

Although it is more cost-effective, producing hydrogen through acidic seawater splitting systems is still difficult, especially when it comes to creating highly effective, highly resistant chlorine corrosion bifunctional catalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, under the addition of phosphotungstic acid and the etching effect of oxalic acid, we develop bifunctional P/W dual-doped RuO_x nanocrystals for acidic overall seawater splitting, showing overpotentials of 45 and 158 mV for the HER and OER at 10 mA cm⁻², respectively, and accompanied by a strong corrosion resistance towards seawater. Accordingly, the two-electrode system requires only 1.47 V to reach a current density of 10 mA cm⁻² and maintains a high stability over 50 h. The P/W dual doping modulates the electrical environment of Ru sites, and the addition of oxalic acid encourages the exposure of more active sites, both of which contribute to the enhancement of seawater electrolysis. Theoretical calculations further manifest that the energy barriers of the HER and OER can be lowered by the dual-doping. Moreover, we found a positive influence of Cl⁻ on the catalytic activity of acidic seawater splitting. Our work offers a promising strategy to significantly increase the catalytic efficiency of Ru-based catalysts for the generation of green hydrogen from acidic seawater in a sustainable manner.