Monoatomic Platinum-Embedded Hexagonal Close-Packed Nickel Anisotropic Superstructures as Highly Efficient Hydrogen Evolution Catalyst

Abstract

The rational design of platinum (Pt) based nanostructures with specific crystal structure plays a significant role in their diverse applications. Herein, the anisotropic superstructures (ASs) of monoatomic Pt-embedded hexagonal close-packed nickel (hcp Ni) nanosheets were successfully synthesized for efficient hydrogen evolution in which an unusual dissociation−diffusion−desorption mechanism played a crucial role. The overpotential for the Pt/Ni ASs to reach the specific current density (10 mA cm −2 ) is 28.0 mV, which is much lower than that of conventional Pt/C catalyst (71.0 mV). Moreover, at the overpotential of 100 mV, the mass activity of 30.2 A mg Pt −1 for the Pt/Ni ASs is 1060% greater than that in conventional Pt/C catalyst (2.6 A mg Pt −1 ). This work provides a new approach to synthesize highly anisotropic superstructures embedded with monoatomic noble metals to boost their hopeful applications in catalytic applications.

Applications of Nickel‐Based Electrocatalysts for Hydrogen Evolution Reaction

“…Ding et al prepared the anisotropic superstructures of the single Pt atom‐anchored hexagonal closed‐packed Ni (Pt/Ni ASs) nanosheets by a facial solvothermal method. [ 58 ] The Pt/Ni ASs as HER catalyst show an overpotential of 28 mV to reach 10 mA cm −2 and the mass activity is 1060% higher that of Pt/C in alkaline media. Based on first‐principles calculations, the pristine Ni was more favorable for water dissociation, while the single Pt atom was responsible for hydrogen formation.…”

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

“…8 It is therefore hinted that in a phase-separated Pt-TM binary system, the water dissociation should mainly occur in the inside region of the TM phase, rather than the interfacial sites. 2,10 In this case, the formed *H has to be transferred from the TM phase to the Pt phase in the rst place, followed by the hydrogen combination and desorption on Pt sites. [11][12][13] In this regard, hydrogen spillover is a recent focus that offers new insights to enhance the *H supply and HER activity of binary catalysts.…”

“…15,18 Interestingly, due to the moderate DG 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][20][21] Although hydrogen spillover was rst discovered in acidic HER systems, current research has also witnessed the spillover behavior in the alkaline HER, which is benecial to strengthening the *H supply for Pt-based binary catalysts in alkali. 10,12,22,23 It must be pointed out that because hydrogen spillover from strong to weak *H sites is intrinsically thermodynamically unfavorable, it will inevitably require an adequate driving force.…”

“…10,13,[19][20][21] Although hydrogen spillover was rst discovered in acidic HER systems, current research has also witnessed the spillover behavior in the alkaline HER, which is benecial to strengthening the *H supply for Pt-based binary catalysts in alkali. 10,12,22,23 It must be pointed out that because hydrogen spillover from strong to weak *H sites is intrinsically thermodynamically unfavorable, it will inevitably require an adequate driving force. 18 Moreover, the hydrogen spillover across the interfaces has to overcome the high migration kinetic barriers.…”

“…Consequently, manipulation of the interfacial migration of *H is of particular importance to optimize the catalytic activity. To this end, some previous works showcase the potential impacts of catalyst structure (such as particle size 24 or crystalline phase 10 ) and ligand modification 18 on the hydrogen spillover process. However, the strategy to thermodynamically and kinetically accelerate interfacial hydrogen migration is still insufficient for Pt-based binary catalysts, hindering the further improvement of their alkaline HER activity.…”