AuPt Bipyramid Nanoframes as Multifunctional Platforms for In Situ Monitoring of the Reduction of Nitrobenzene and Enhanced Electrocatalytic Methanol Oxidation

Abstract

Multifunctional metal nanostructures with a hollow feature, especially for nanoframes, are highly attractive owing to their high surface‐to‐volume ratios. However, pre‐grown metal nanocrystals are always involved during the preparation procedure, and a synthetic strategy without the use of a pre‐grown template is still a challenge. In this article, a template‐free strategy is reported for the preparation of novel AuPt alloy nanoframes through simply mixing HAuCl4 and H2PtCl6 under mild conditions. The alloy nanostructures show a bipyramid‐frame hollow architecture with the existence of only the ten ridges and absence of their side faces. This is the first report of bipyramid‐like nanoframes and a template‐free method under mild conditions. This configuration merges the plasmonic features of Au and highly active catalytic sites of Pt in a single nanostructure, making it an ideal multifunctional platform for catalyzing and monitoring the catalytic reaction in real time. The superior catalytic activity is demonstrated by using the reduction of nitrobenzene to the corresponding aminobenzene as a model reaction. More importantly, the AuPt nanoframes can track the reduction process on the basis of the SERS signals of the reactants, intermediates, and products, which helps to reveal the reaction mechanism. In addition, the AuPt nanoframes show much higher electrocatalytic properties toward the methanol oxidation reaction than commercial Pt/C electrocatalysts.

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible‐Light Illumination

“…We had to prolong the reaction time to over 30 h to obtain Au nanobowls with high purity (Figure S4 d–f in the Supporting Information). Taking the above observations together, we hypothesized that Pt 4+ serves as the directing agent during the growth process, leading to the formation of polyhedral morphology (Figure h). Pt atoms from the reduction of H 2 PtCl 6 are deposited on the surface of the Au{111} seeds.…”

“…For instance, the plasmonic bands of Au nanostructures can be manipulated in a broad range from 560 to over 1100 nm by changing their morphologies and sizes, which facilitates their activity in solar‐driven catalytic reactions . Moreover, Au NCs with high curvature offer a much higher electromagnetic field intensity under light excitation . Such a high electric field is greatly beneficial for the formation of hot carriers, and thus brings great improvement in catalytic activity.…”

Bimetallic Nanocrystals: Structure, Controllable Synthesis and Applications in Catalysis, Energy and Sensing

“…The second metal is grown on the template, and then the template is removed by acid etching or electric displacement to obtain a bimetal frame structure. Metals commonly used as templates are noble metals (Pd [ 81 ], Ag [ 82 , 83 , 84 ] and Au [ 75 , 85 ]) and transition metal (Cu [ 86 , 87 , 88 ] and Ni [ 89 , 90 ]). Some synthesized frame structures developed up until now are shown in Figure 5 .…”

“…Copyright American Chemical Society, 2018. Bipyramid: ( p ) AuPt, Reproduced with permission from [ 85 ]. Copyright Wiley-VCH, 2019.…”

Platinum‐Based Electrocatalysts for Direct Alcohol Fuel Cells: Enhanced Performances toward Alcohol Oxidation Reactions

“…To date, the widely employed methods for estimating the durability of Pt‐based nanocatalysts to AOR are CA tests and cycling stability measurements, which are generally performed in a mixture of alcohol molecules in an acid or alkaline. For CA evaluation, it tracks the activity variations over a period under a continuous electrocatalytic scan at a fixed potential (Figure 1h) [18,42] . For cycling stability measurement, the CV curves are recorded for hundreds or thousands or even more cycles and then compared the final activity with the pristine one [43] .…”