Pt(II) as an active site supported on superhydrophilic nickel foam with boosted electrocatalytic hydrogen evolution performance

Abstract

In the search for a viable power to hydrogen conversion technology, the electrochemical hydrogen evolution reaction (HER) promises to be the future. However, the rational design of highly active and durable electrocatalysts for this system remains a challenge. Here, we introduce Pt(II) species supported on binder-free superhydrophilic nickel foam (NiF(H)) as an HER electrocatalyst. We show that the superhydrophilic layer on the surface of Pt(II)/NiF(H) enhances the detachment of hydrogen bubbles from the surface of the electrode and also decreases the resistances emanating from the Volmer and Heyrovsky steps. In-situ Raman spectra results indicate that Pt(II)/NiF(H) can effectively accelerate water adsorption and dissociation steps. Density functional theory(DFT) calculations demonstrate that the surface of Pt(II)/NiF(H) can effectively tune the hydrogen adsorption-free energy to a favorable value, improving the HER activity. In addition, the superhydrophilic layer acts as a platform that can fully stabilize the Pt(II) species in the long-term HER process. The Pt(II)/NiF(H) catalyst is more active than a commercial Pt/C(20%) and other control samples, exhibiting a small overpotential (η) of 26 mV to drive a current density of 10 mA cm-2. In addition, the Pt(II)/NiF(H) achieves high mass activities of 8.9 A mgPt-1 at overpotentials of 100 mV, indicating a high utilization of Pt. This work provides a feasible constructive guideline for the rational design of an advanced high-valence-state Pt-based electrocatalyst for HER.