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Interfacing Plasmonic Nanoparticles with Ferroelectrics for Hot-Carrier-Driven Photocatalysis: Impact of Schottky Barrier Height

2019; American Chemical Society; Volume: 2; Issue: 10 Linguagem: Inglês

10.1021/acsaem.9b01682

2574-0962

Vineet Kumar, Shaun O’Donnell, Brandon Zoellner, Jhon Martinez, Gufeng Wang, Paul A. Maggard,

Quantum Dots Synthesis And Properties

Emergent strategies for efficient solar energy conversion have focused on ways to harness photons in the lower-energy range of sunlight that cannot be utilized by conventional semiconductor photocatalyst systems. Recent research has demonstrated that interfaced plasmonic–ferroelectric particles represent a promising strategy for the utilization of near-infrared (NIR) light owing to the possibility of the more efficient injection of hot charge carriers from noble metal nanoparticles. Described herein, platinum-end-capped gold nanorods (AuNRs) function as antennae to absorb low-energy NIR photons to generate hot electrons that can be injected into ferroelectric PbZrxTi1–xO3 (PZT; x = 0.48, 0.50, 0.52, 0.54, 0.56, and 0.60) and drive the reduction of water to molecular hydrogen at its surfaces. As an aqueous suspension, the interfaced AuNR-PZT particles exhibited maximal photocatalytic rates for hydrogen formation under a 976 nm diode laser (powder density = 2.0 W cm–2) for the 52% Zr (x = 0.52) composition at a photon conversion efficiency of ∼0.28%. This efficiency is significantly higher than in previously reported metal–semiconductor combinations, i.e., of ∼0.01% to 0.1%, owing to the large ferroelectric polarization of PZT at its morphotropic phase boundary that yields the smallest Schottky barrier height. Reduction of the Schottky barrier height at the AuNR-PZT interface results from the effect of the surface electric polarization on interfacial band bending, and helps to drive charge injection and the photocatalytic activity for molecular hydrogen production. Photocatalytic rates were also measured as a function of the irradiant power density, ranging from ∼0.1 to 2.0 W cm–2, and exhibited an increasing, nonlinear dependence that is consistent with the production rate of hot electrons above the Schottky barrier. Thus, this study reveals original insights into the critical parameters needed to design integrated plasmonic–ferroelectric photocatalyst systems for utilizing hot electrons produced from NIR light and achieving higher solar conversion efficiencies.