Ultrasmall Pt Nanoparticles-Loaded Crystalline MoO<sub>2</sub>/Amorphous Ni(OH)<sub>2</sub> Hybrid Nanofilms with Enhanced Water Dissociation and Sufficient Hydrogen Spillover for Hydrogen Generation
Wuzhengzhi Zhang, Lianchun Ding, Weipei Sun, Tian Sheng, Zhengcui Wu, Feng Gao
Abstract
Generating hydrogen via the alkali-water electrocatalytic hydrogen evolution reaction (HER) is a prospective avenue, in which the key point is to construct the electrocatalyst with excellent catalytic behavior. Herein, a Pt nanoparticles-loaded crystalline MoO2/amorphous Ni(OH)2 hybrid nanosheets-composed nanofilm (PtNPs-c-MoO2/a-Ni(OH)2NF) on Ni foam was designed via a one-step solution-phase strategy for the alkaline HER. The hydrophilic amorphous Ni(OH)2 in the hybrid nanosheets accelerated water dissociation, and the spillover effect of H atoms from Pt nanoparticles to MoO2 in the hybrid nanosheets increased the utilization of the dissociated H atoms; moreover, the MoO2 and the Ni(OH)2 heterostructure in the hybrid nanosheets exposed copious active edge sites, which jointly enhanced the HER performance of the Pt NPs-c-MoO2/a-Ni(OH)2NF. The density functional theory (DFT) results showed that the water dissociation at Pt/Ni(OH)2 (−0.24 eV) is thermodynamically more favored than that on Pt(111) (0.62 eV), and the recombination of one H* on Pt and one H* on MoO2 could significantly reduce the energy barrier to only 0.05 eV. The optimized Pt1.07%NPs-c-MoO2/a-Ni(OH)2NF with ∼2 nm ultrasmall Pt nanoparticles can achieve 10 mA cm–2 at an ultralow overpotential of 18 mV and 500 mA cm–2 at a low overpotential of 167 mV with superior long-term steadiness. Moreover, the mass activity of Pt1.07%NPs-c-MoO2/a-Ni(OH)2NF achieved 8.24 mA μgPt–1 at an overpotential of 70 mV, nearly 21.7-fold that of commercial Pt/C. Our synthesis strategy can be extended to obtain the Pd or Au nanoparticles-loaded c-MoO2/a-Ni(OH)2 nanofilm with low noble-metal content for enhanced HER activities.