Hierarchical porous Co-rich PtCo thin films for alkaline seawater hydrogen evolution with chlorine corrosion resistance

Abstract

The creation of cost-effective and efficient catalysts for hydrogen evolution in seawater is highly desirable, yet it still poses considerable challenges. In this work, hierarchical porous Co-rich PtCo thin films were successfully prepared by one-step electrodeposition with nonionic surfactant F127 as a soft template to introduce mesoporosity. The effect of varying deposition potentials on the composition, morphology, structure and porosity of the films was systematically investigated. The composition can be adjusted with the deposition potential to achieve a Co content within 50–84 at%. XRD, HRTEM, and SAED analyses show that the films are single-phase nanocrystalline fcc PtCo. The hydrogen evolution reaction (HER) activity and stability of these films were assessed under multiple conditions: 1 M KOH, 1 M KOH with 3.5 wt% NaCl, and 1 M KOH with natural seawater. For the Pt/Co ratio of 34 : 66, the overpotential is as low as 30 mV at a current density of −10 mA cm⁻² in alkaline natural seawater. Furthermore, it demonstrated enhanced stability, showing negligible performance degradation even after continuous 24 h at 10 mA cm⁻². The excellent seawater HER performance of Pt₃₄Co₆₆ can be attributed to its hierarchical porous structure with mesopores and electron accumulation on Pt. The results presented herein have the potential to promote the large-scale development of seawater hydrogen production.