The design of highly efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) is a critical endeavor, especially in alkaline electrolytes. Herein, we report the development of ultralow-amount Pt-decorated Ni−P catalysts on nickel foam substrates (Pt/Ni−P/NF) via a facile electroless deposition of Ni−P alloys subsequently decorated with a very small amount of Pt nanoparticles through a dip-coating procedure. Benefiting from the 3D porous backbone of the NF substrate and from the synergistic effect between Ni−P and Pt, the present Pt/Ni−P/NF catalyst demonstrates superior HER activity compared to most of the state-of-the-art Pt-based electrocatalysts, with a very low overpotential (22 mV at 10 mA cm −2 ) and Tafel slope (30 mV dec −1 ) and a high turnover frequency (1.78 s −1 ) at η = 50 mV. Furthermore, a full alkaline electrolyzer is constructed using Pt/Ni−P/NF as the cathode and undecorated Ni−P as the anode, which can drive overall water splitting with a low potential of 1.64 V at 10 mA cm −2 . This work engenders novel possibilities toward the design of advanced ultralow-content Pt electrocatalysts fulfilling both excellent HER performance and low-cost requirements.
Surface decoration by means of metal nanostructures is an effective way to locally modify the electronic properties of materials. The decoration of ZnO nanorods by means of Au nanoparticles was experimentally investigated and modelled in terms of energy band bending. ZnO nanorods were synthesized by chemical bath deposition. Decoration with Au nanoparticles was achieved by immersion in a colloidal solution obtained through the modified Turkevich method. The surface of ZnO nanorods was quantitatively investigated by Scanning Electron Microscopy, Transmission Electron Microscopy and Rutherford Backscattering Spectrometry. The Photoluminescence and Cathodoluminescence of bare and decorated ZnO nanorods were investigated, as well as the band bending through Mott–Schottky electrochemical analyses. Decoration with Au nanoparticles induced a 10 times reduction in free electrons below the surface of ZnO, together with a decrease in UV luminescence and an increase in visible-UV intensity ratio. The effect of decoration was modelled with a nano-Schottky junction at ZnO surface below the Au nanoparticle with a Multiphysics approach. An extensive electric field with a specific halo effect formed beneath the metal–semiconductor interface. ZnO nanorod decoration with Au nanoparticles was shown to be a versatile method to tailor the electronic properties at the semiconductor surface.
Decoration of nanostructures is a promising way of improving performances of nanomaterials. In particular, decoration with Au nanoparticles is considerably efficient in sensing and catalysis applications. Here, the mechanism of decoration with Au nanoparticles by means of low-cost electroless deposition (ELD) is investigated on different substrates, demonstrating largely different outcomes. ELD solution with Au potassium cyanide and sodium hypophosphite, at constant temperature (80 °C) and pH (7.5), is used to decorate by immersion metal (Ni) or semiconductor (Si, NiO) substrates, as well as NiO nanowalls. All substrates were pre-treated with a hydrazine hydrate bath. Scanning electron microscopy and Rutherford backscattering spectrometry were used to quantitatively analyze the amount, shape and size of deposited Au. Au nanoparticle decoration by ELD is greatly affected by the substrates, leading to a fast film deposition onto metallic substrate, or to a slow cluster (50–200 nm sized) formation on semiconducting substrate. Size and density of resulting Au clusters strongly depend on substrate material and morphology. Au ELD is shown to proceed through a galvanic displacement on Ni substrate, and it can be modeled with a local cell mechanism widely affected by the substrate conductivity at surface. These data are presented and discussed, allowing for cheap and reproducible Au nanoparticle decoration on several substrates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.