Synergistic effect between undercoordinated platinum atoms and defective nickel hydroxide on enhanced hydrogen evolution reaction in alkaline solution

Abstract

Improving the hydrogen evolution reaction (HER) performance of Pt based catalysts in alkaline environment is of key importance in various industrial processes and remains a challenge so far. Given the lower energy barriers of water dissociation upon the undercoordinated Pt and oxophilic species, engineering Pt based catalysts possessed the high density of surface atomic steps, ledges, and kinks with Ni(OH)2 are an effective way to endow Pt with high catalytic HER activity. Based on density functional theory (DFT) models, we demonstrated that the energy barrier of water dissociation process could be significantly reduced by the synergistic effect of undercoordinated Pt atoms and defective Ni(OH)2. This hypothesis has been further validated by experimental results that concave nanocube (CNC) Pt-Mn particles exposed by high indexed facets (HIFs) supported on the Ni(OH)2 nanosheets exhibited 6.88 times specific current density (4.80 times mass current density) higher than nanocube Pt-Mn particles mainly exposing non-defective surface. Moreover, the in situ electrochemical etching experiments suggested that the enhanced HER performance was attributed to the synergistic effect of Ni(OH)2 and Pt, rather than the increase of active sites for Pt via calculating the electrochemical surface area (ECSA) values. Thus, this work provides an insight for rational design of Pt based nanocomposite with enhanced catalytic properties for alkaline HER under the guidance of computational modeling.