Two-dimensional siloxene as an advanced support of platinum for superior hydrogen evolution and methanol oxidation electrocatalysis

Abstract

To improve the utilization efficiency of versatile platinum (Pt) in electrochemical energy conversion, precisely choosing support materials is a significantly promising strategy. Herein, we demonstrate the competitive advantages of novel two-dimensional Siloxene as the advanced support of Pt toward enhancing bifunctional electrocatalysis for hydrogen evolution (HER) and methanol oxidation (MOR) based on unusual metal–support interactions. The Pt NPs/Siloxene electrocatalyst by supporting Pt nanoparticles on Siloxene sheets is successfully synthesized via simple wet-chemical method. Compared to commercial Pt/C (20 wt%), Pt NPs/Siloxene with ultra-low Pt content (1.3 wt%) exhibits superior electrocatalytic activity with good stability toward HER and MOR in acidic media. For HER, a small overpotential of 24 mV is required to drive 10 mA cm−2 current with a low Tafel slope (24.6 mV dec−1). Meanwhile, preeminent Pt mass activity of 1957 mA mg−1 for MOR is achieved, which is 12.6 times higher than that of Pt/C. Theoretical calculations indicate that the binding energies are optimized to facilitate desorption or adsorption of related adsorbates during HER and MOR electrocatalysis, and thus enhancing Pt utilization efficiency. Specially, this support engineering can trigger hydrogen spillover from Pt to Siloxene to promote hydrogen generation, attributed to a unique hydrogen spillover-based HER pathway with favorable proton adsorption on Pt sites and efficient hydrogen desorption from Siloxene.