Controllable Synthesis and Atomic Scale Regulation of Noble Metal Catalysts

Nanomaterials are defined as nanoscale materials with a size range of 1–100 nm in the three-dimensional space. They feature a single-domain crystal without complex grain boundaries. As a bridge between atoms and bulk materials, nanocrystals received a booming research interest due to their unique properties.

Metal nanoparticles (NPs) are emerging as a central nanomaterial for catalysis, Nørskov et al., Chem Soc Rev37:2163–2171 (2008) (Nørskov et al. in Chem Soc Rev 37:2163–2171, 2008) plasmonic, Pelton et al., Laser Photon Rev 2:136–159 (2008) (Pelton et al. in Laser Photonics Rev 2:136–159, 2008) sensing, Doria et al., Sensors 12:1657–1687 (2012) (Doria et al. in Sensors 12:1657–1687, 2012) and so on.

Single-atom precious metal catalysts hold the promise of perfect atom utilization, yet control of their activity and stability remains challenging. Here we show that engineering the electronic structure of atomically dispersed Ru1 on metal supports via compressive strain boosts the kinetically sluggish electrocatalytic oxygen evolution reaction (OER), and mitigates the degradation of Ru-based electrocatalysts in an acidic electrolyte. We construct a series of alloy-supported Ru1 using different PtCu alloys through sequential acid etching and electrochemical leaching, and find a volcano relation between OER activity and the lattice constant of the PtCu alloys. Our best catalyst, Ru1–Pt3Cu, delivers 90 mV lower overpotential to reach a current density of 10 mA cm−2, and an order of magnitude longer lifetime over that of commercial RuO2. Density functional theory investigations reveal that the compressive strain of the Ptskin shell engineers the electronic structure of the Ru1, allowing optimized binding of oxygen species and better resistance to over-oxidation and dissolution.

The efficient electrochemical hydrogen evolution reaction (HER) plays a key role in accelerating sustainable H2 production from water electrolysis, but its large-scale applications are hindered by the high cost of the state-of-the-art Pt catalyst. In this work, submonolayer Pt was controllably deposited on an intermetallic Pd3Pb nanoplate (AL-Pt/Pd3Pb). The atomic efficiency and electronic structure of the active surface Pt layer were largely optimized, greatly enhancing the acidic HER. ALPt/Pd3Pb exhibits an outstanding HER activity with an overpotential of only 13.8 mV at 10 mA/cm2 and a high mass activity of 7834 A/gPd+Pt at −0.05 V, both largely surpassing those of commercial Pt/C (30 mV, 1486 A/gPt). In addition, AL-Pt/Pd3Pb shows excellent stability and robustness. Theoretical calculations show that the improved activity is mainly derived from the charge transfer from Pd3Pb to Pt, resulting in a strong electrostatic interaction that can stabilize the transition state and lower the barrier.

Noble metal nanocrystals that are regarded as promising candidates have been widely applied in energy conversion and storage. This thesis is mainly involved in the controllable synthesis of novel ternary noble metal nanocrystals and their applications, of which are briefly introduced in the following.