Hydrogen spillover in complex oxide multifunctional sites improves acidic hydrogen evolution electrocatalysis

Abstract

Improving the catalytic efficiency of platinum for the hydrogen evolution reaction is valuable for water splitting technologies. Hydrogen spillover has emerged as a new strategy in designing binary-component Pt/support electrocatalysts. However, such binary catalysts often suffer from a long reaction pathway, undesirable interfacial barrier, and complicated synthetic processes. Here we report a single-phase complex oxide La2Sr2PtO7+δ as a high-performance hydrogen evolution electrocatalyst in acidic media utilizing an atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from comprehensive experiments and theoretical calculations, the overall hydrogen evolution pathway proceeds along three steps: fast proton adsorption on O site, facile hydrogen migration from O site to Pt site via thermoneutral La-Pt bridge site serving as the mediator, and favorable H2 desorption on Pt site. Benefiting from this catalytic process, the resulting La2Sr2PtO7+δ exhibits a low overpotential of 13 mV at 10 mA cm−2, a small Tafel slope of 22 mV dec−1, an enhanced intrinsic activity, and a greater durability than commercial Pt black catalyst.

Coupling of nanocrystal hexagonal array and two-dimensional metastable substrate boosts H2-production

“…In addition, metastable metal oxides provide extensive possibilities for synthesizing the interfacial structures due to their intrinsic metastable properties 33 – 35 . Furthermore, in the metal/oxide catalytic interfacial system, the hydrogen spillover effect can cause the activated hydrogen atoms to migrate from a hydrogen-rich area to a hydrogen-poor area, which may provide an effective way to further improve the HER activity 36 , 37 .…”

Boosting the interfacial hydrogen migration for efficient alkaline hydrogen evolution on Pt-based nanowires

“…In addition, the sensitivity of the hydrogen desorption peak position to the scan rate during CV investigations can be used as a descriptor to reflect the hydrogen desorption kinetics and evidence the occurrence of hydrogen spillover. 15,45 As Fig. 4h and S29† show, the hydrogen desorption peak shifts positively with increasing scan rate for all catalysts, among which the PtNiP-0.11 NWs possess the lowest slope value.…”

“…In this regard, hydrogen spillover is a recent focus that offers new insights to enhance the *H supply and HER activity of binary catalysts. 12,14–17 Hydrogen spillover typically proceeds through hydrogen migration from H-enriched sites (strong *H adsorption sites) to H-deficient sites (weak *H adsorption sites), similar to the case of the abovementioned binary system. 15,18 Interestingly, due to the moderate Δ G H on Pt sites close to the thermoneutral point, Pt atoms can act as *H donating sites or accepting sites depending on the *H binding strength of the secondary component.…”

“…12,14–17 Hydrogen spillover typically proceeds through hydrogen migration from H-enriched sites (strong *H adsorption sites) to H-deficient sites (weak *H adsorption sites), similar to the case of the abovementioned binary system. 15,18 Interestingly, due to the moderate Δ G H on Pt sites close to the thermoneutral point, Pt atoms can act as *H donating sites or accepting sites depending on the *H binding strength of the secondary component. 10,13,19–21 Although hydrogen spillover was first discovered in acidic HER systems, current research has also witnessed the spillover behavior in the alkaline HER, which is beneficial to strengthening the *H supply for Pt-based binary catalysts in alkali.…”

“…18 Moreover, the hydrogen spillover across the interfaces has to overcome the high migration kinetic barriers. 15 These two challenges could give rise to less motivated or even frustrated hydrogen spillover on binary catalysts under HER conditions. Consequently, manipulation of the interfacial migration of *H is of particular importance to optimize the catalytic activity.…”